CN111178657A - AC-DC hybrid distributed system electric loss and energy efficiency evaluation method based on star - Google Patents

AC-DC hybrid distributed system electric loss and energy efficiency evaluation method based on star Download PDF

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CN111178657A
CN111178657A CN201910772203.5A CN201910772203A CN111178657A CN 111178657 A CN111178657 A CN 111178657A CN 201910772203 A CN201910772203 A CN 201910772203A CN 111178657 A CN111178657 A CN 111178657A
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江红胜
韩庆浩
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Cmig New Energy Investment Group Co ltd
State Grid Jiangsu Electric Power Co Ltd
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Abstract

The invention discloses a method based on
Figure DDA0002173943360000011
The alternating current-direct current hybrid distributed system comprises an alternating current-direct current power supply system, a distributed energy supply system, a thermodynamic system and an energy storage system; the method comprises the steps of calculating the electric loss of the alternating current and direct current power supply system, calculating the electric loss of the distributed energy supply system, calculating the electric loss of the thermodynamic system, calculating the electric loss of the energy storage system, and respectively acquiring the electric losses of the alternating current and direct current power supply system, the distributed function system, the thermodynamic system and the energy storage system according to the electric losses of the alternating current and direct current power supply system, the distributed function system, the thermodynamic system and the energy storage system
Figure DDA0002173943360000012
Efficiency and ultimately the power of the AC/DC hybrid distributed system
Figure DDA0002173943360000013
Efficiency. The advantages are that: the comprehensive energy loss rate in the system is obtained by calculating various electric losses and heat losses in the system so as to obtain
Figure DDA0002173943360000014
And establishing an index system as a parameter for evaluating the system loss, and quantitatively analyzing the energy utilization efficiency of the system.

Description

AC-DC hybrid distributed system electric loss and energy efficiency evaluation method based on star
Technical Field
The invention relates to the field of distributed system energy conservation in an electric power system, in particular to a method based on
Figure RE-GDA0002399608310000012
The method for evaluating the electric loss and the energy efficiency of the alternating current and direct current hybrid distributed system.
Background
Distributed systems have been rapidly developed in recent years, and distributed system demonstration projects which take comprehensive utilization of multiple types of energy resources as main characteristics are receiving wide attention. However, unlike a large power grid, a distributed system has a short transmission distance, and many energy forms exist in the system, and not only includes electric energy transmission, but also includes production, transmission and use of heat energy, and particularly, in an alternating current and direct current hybrid distributed system, electric energy loss calculation is complex in two transmission ways of alternating current and direct current. Therefore, it is very difficult to perform power loss calculation and energy efficiency evaluation for distributed systems.
At present, scholars at home and abroad make certain research on energy efficiency, and analyze the energy utilization efficiency of electricity users in a fixed area by taking the electricity users as evaluation targets, but the quantitative analysis is usually aimed at single aspect and single-index quantification, so that the energy efficiency evaluation of all equipment types and all energy utilization scenes in an energy utilization area cannot be considered at the same time. Especially, energy efficiency analysis performed on a distributed system is usually performed only on a pure alternating current distributed system, but not on an alternating current/direct current hybrid distributed system.
Disclosure of Invention
The invention aims to provide a method based on
Figure RE-GDA0002399608310000013
The method for evaluating the electric loss and the energy efficiency of the alternating current and direct current hybrid distributed system solves the problems in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
based on
Figure RE-GDA0002399608310000014
The alternating current-direct current hybrid distributed system comprises an alternating current-direct current power supply system, a distributed energy supply system, a thermodynamic system and an energy storage system; comprises the following steps of (a) carrying out,
s1, calculating the electric loss of the alternating current and direct current power supply system;
s2, calculating the electric loss of the distributed energy supply system;
s3, calculating the electric loss of the thermodynamic system;
s4, calculating the electric loss of the energy storage system;
s5, respectively obtaining the electric losses of the AC/DC power supply system, the distributed function system, the thermodynamic system and the energy storage system according to the electric losses of the AC/DC power supply system, the distributed function system, the thermodynamic system and the energy storage system
Figure RE-GDA0002399608310000021
Efficiency and ultimately the power of the AC/DC hybrid distributed system
Figure RE-GDA0002399608310000022
Efficiency.
Preferably, the step S1 specifically includes,
s11, calculating the line loss of the AC/DC power supply system;
s12, calculating the loss of the power electronic transformer;
s13, calculating the loss of the rectifier;
and S14, acquiring the electric loss of the alternating current and direct current power supply system according to the line loss, the loss of the power electronic transformer and the loss of the rectifier.
Preferably, the step S11 includes the following specific contents,
s111, calculating and counting line loss; the statistical line loss is the difference between the power supply amount and the power selling amount, and the calculation formula is that the statistical line loss is [ (power supply amount-power selling amount)/power supply amount ] × 100%;
s112, calculating theoretical line loss; the theoretical line loss is calculated theoretically according to parameters of power supply equipment, the current running mode of the power grid, the current distribution and the load condition;
s113, calculating the management line loss; the management line loss is the loss electric quantity generated by factors in management, and the calculation formula is that the management line loss is statistical line loss (actual line loss) -theoretical line loss;
s114, calculating economic line loss; the theoretical line loss of a line with fixed equipment conditions changes along with the change of the electric load, the line loss rate is the lowest, the lowest line loss rate is the economic line loss, and the corresponding current becomes the economic current;
s115, calculating rated line loss; the rated line loss is a line loss index approved by a higher level through measurement and calculation according to the actual line loss of the power network and by combining the power network structure, the load flow condition and the loss reduction measure arrangement condition in the next assessment period;
and S116, adding the statistical line loss, the theoretical line loss, the management line loss, the economic line loss and the rated line loss to obtain the line loss of the alternating current and direct current power supply system.
Preferably, step S12 includes the following specific contents,
s121, calculating hysteresis loss of the power electronic transformer; the hysteresis loss frequency is proportional to the second power of the hysteresis coefficient of the maximum magnetic flux density, and the loss caused by hysteresis under harmonic conditions can be expressed as,
Figure RE-GDA0002399608310000031
wherein, PHnFor hysteresis losses, n is the harmonic order, UnIs an nth harmonic voltage (V), U1Is the fundamental voltage (V), phinIs n timesHarmonic voltage initial phase angle (degree), s is the core material coefficient;
s122, calculating the eddy current loss of the power electronic transformer; the eddy current loss is the loss caused by eddy current in the iron core, the leakage magnetic field in the transformer is divided into an axial leakage magnetic field and a radial leakage magnetic field, the loss caused by the induction intensity is also divided into an axial eddy current loss and a radial eddy current loss, the calculation formula is as follows,
Figure RE-GDA0002399608310000032
wherein, BriIs the radial magnetic induction intensity (T), B in the ith cellziThe axial magnetic induction intensity (T) in the ith unit, omega is angular frequency (Hz), rho is material resistivity (omega. m), b and d are wire sizes, RiIs the distance (mm) from the center of gravity of the ith unit to the center line of the iron core, ViThe volume occupied by the conductor in the ith cell (mm 3);
s123, calculating the winding loss of the power electronic transformer; the winding loss consists of basic copper loss and additional copper loss, the loss caused by the direct current resistance of a winding coil at the primary side and the secondary side of the transformer is called as basic copper loss, the effective resistance of a lead can be increased to generate the additional copper loss due to the skin effect and the proximity effect caused by a leakage magnetic field, the additional copper loss also comprises the eddy current loss generated by the wall of an oil tank and a metal structural member and the internal circulating current loss generated by the parallel winding of the lead, under the direct current magnetic biasing effect, the calculation formula of the winding loss is as follows,
Figure RE-GDA0002399608310000033
wherein, PjnIs the winding loss (W), Rn(1)、Rn(2) Is the resistance (omega) of the primary winding and the secondary winding under the nth harmonic,
Figure RE-GDA0002399608310000034
is the effective value (I) of the harmonic current flowing through the primary and secondary windings;
and S124, adding the hysteresis loss, the eddy current loss and the winding loss to obtain the loss of the power electronic transformer.
Preferably, the rectifier is controlled by PWM, and the step S13 includes the following specific contents,
s131, calculating average conduction loss; when the rectifier is in the on state and conducts current, the product of the on state saturation voltage and the on state current forms the conduction loss, the conduction loss must be multiplied by the duty cycle factor to obtain the average loss, the average conduction loss of the rectifier is as follows,
Figure RE-GDA0002399608310000041
wherein, PSSTo average conduction loss, ICPIs the peak value of the sinusoidal output current; vCE(sat)Is the peak current ICPThe saturation voltage drop of the lower IGBT; d is the duty cycle; theta is a power factor angle;
s132, calculating average switching loss; the switching loss is the power loss during the transition process of switching on and switching off the tube, the average switching loss is obtained by multiplying the unit pulse total switching energy by the PWM frequency,
PSW＝fPWM×(ESW(on)+ESW(off))
wherein, PSWTo average switching losses, fPWMTo the PWM frequency, ESW(on)And ESW(off)The energy of the unit pulse master switch when the unit pulse master switch is opened and closed respectively.
Preferably, the distributed energy supply system comprises a combined cooling heating and power supply system and a photovoltaic distributed device; the step S2 includes the following specific contents,
s21, reflecting the power consumption of the combined cooling heating and power system through electric efficiency and energy cascade utilization; respectively calculating equivalent electric efficiency, reduced electric efficiency, energy cascade utilization rate and energy saving rate of the combined cooling heating and power system;
the equivalent electric efficiency is the ratio of the equivalent electric quantity to the primary energy consumption of the combined cooling, heating and power system, the equivalent electric quantity is the electric quantity consumed by the corresponding conventional system for outputting the same cooling or heating quantity respectively by converting the cooling or heating quantity in the combined cooling, heating and power system, the equivalent electric efficiency is calculated as follows,
Figure RE-GDA0002399608310000042
wherein eta is1For equivalent electric efficiency, COPhThe heat supply coefficient of the electric heat pump;
the reduced power generation rate is the power generation efficiency calculated when the energy consumption of cold output and the energy consumption of heat output in the cold-heat-electricity combined supply system are assumed to be the same as the conventional reference, the calculation formula is as follows,
Figure RE-GDA0002399608310000043
wherein eta is2Reduced electrical efficiency;
the energy cascade utilization rate comprehensively considers the performance of the cooling, heating and power products from the perspective of energy taste and cascade utilization, expresses the inequivalence of different products by taking uniformly quantized energy level taste coefficients as weight coefficients of cold, heat and power, considers the quantity and grade of consumed energy and the change condition along with the change of comparison conditions, and has the calculation formula as follows,
Figure RE-GDA0002399608310000051
Figure RE-GDA0002399608310000052
wherein eta is3The energy step utilization rate; a. theeEnergy level taste coefficient of electricity; a. thehIs the thermal energy level taste coefficient; a. thecIs the thermal energy level taste coefficient; a. thefIs the energy level taste coefficient of the fuel; delta E is an energy transfer process
Figure RE-GDA0002399608310000053
(ii) a change; Δ H is the enthalpy change during energy transfer;
the energy saving rate is a heat economy analysis method established on the basis of a first thermodynamic law, the energy saving condition of the combined cooling heating and power system is evaluated, and the combined cooling heating and power system is evaluated relative to the primary energy saving rate of the combined cooling heating and power system in the heating period or the cooling period under the condition of supplying the same heat, cooling capacity and electric quantity; the energy-saving rate calculation formulas of the heating period and the cooling period are respectively as follows,
Figure RE-GDA0002399608310000054
Figure RE-GDA0002399608310000055
wherein eta iszhfor saving energy during the heating period etazcis the energy saving rate of the cooling period etaeefficiency of power supply for combined supply [. eta. ]hefficiency of heat supply for combined supply ηbThe heat supply efficiency of the boiler is improved; COPaThe refrigeration coefficient of the absorption refrigerator; COPeThe refrigeration coefficient of the electric refrigerator;
s22, calculating the electrical part loss of the photovoltaic distributed equipment, including the reactive loss of the transformer and the influence of the overall efficiency of the inverter;
the reactive loss of the transformer comprises no-load reactive loss and load reactive loss, the calculation formula is as follows,
QT＝QO.T+QP.T
Figure RE-GDA0002399608310000056
Figure RE-GDA0002399608310000061
wherein Q isTFor reactive losses of transformers, QO.TFor no-load reactive power loss, QP.TFor carrying reactive losses, Ud% is the short-circuit voltage percentage of the transformer; i isOT% is the no-load current percentage of the transformer; sN.TRated capacity for the transformer; sTIs the actual load of the transformer; pPVIs the photovoltaic power transmitted by the transformer;
the efficiency of the inverter directly influences the effective generating capacity and the generating cost of the photovoltaic generating system, so that the inverter has the function of tracking control and management of the maximum power point and can change along with the corresponding change of the radiation capacity of solar energy at any time.
Preferably, the step S3 includes the following specific contents,
s31, calculating heat pump electric losses including the electric losses of the air source heat pump system and the water source heat pump system;
the power consumption condition of the air source heat pump system in a complete heating (frosting)/defrosting (regenerating) period is defined as that the air source heat pump system supplies heat to the indoor in the heating stage as positive, heat is taken from the indoor in the defrosting stage as positive, an energy conservation equation of the air source heat pump system is listed,
a. the heat production (frosting) process has the energy conservation equation as follows,
Qi1＝W1+Qo1
Qo1＝Qo1,s+Qo1,l
wherein Q iso1,sFor sensible heat of the frosting process, Qo1,lLatent heat for the frosting process;
b. in the defrosting (regeneration) process, the air source heat pump system can take heat from a user side and can also take heat from other channels to provide heat required by the defrosting (regeneration) process, the energy conservation equation is,
Qo2＝W2+Qi2
Qo2＝Qo2,s+Qo2,l
wherein Q iso2,sFor sensible heat of the frosting process, Qo2,lLatent heat for the frosting process;
c. actual heating quantity Q of air source heat pump system to user side in one heating/defrosting periodhIn order to realize the purpose,
Qh＝Qi1-Qi2
d. energy efficiency ratio COP of air source heat pump system in frosting/defrosting periodsIn order to realize the purpose,
Figure RE-GDA0002399608310000062
the compressor, the water source pump and the circulating pump in the water source heat pump system are main power consumption equipment;
under different rotating speeds n of the motor, the relation between the power P of the load, the torque T and the rotating speed n is Tn/9550, and when the rotating speed n is 1, the consumed power is P1; when the rotating speed is n2, the consumed power is P2; if n1 is the rated speed, P1 is the rated power consumed;
the torque T of the water source pump load is in direct proportion to the square of the rotating speed n, namely T is KTn2, the relational expression of the power P of the load and the rotating speed n is P Tn/9550 KPn, KP is the power constant of the quadratic load, the power consumed by the water pump is in direct proportion to the rotating speed cube, when the water pump is controlled by a frequency converter to operate, the output frequency of the frequency converter is f1, the rotating speed of the water pump is n1, the flow rate is Q1, and the shaft power of a water pump motor is P1; the frequency converter has the output frequency of f2, the water pump rotating speed of n2, the flow rate of Q2, the shaft power of the water pump motor of P2, and Q1:Q2＝n1:n2， Q1:Q2＝n1:n2I.e. the power consumed by the motor is proportional to the 3 rd power of its rotational speed;
the power consumption of the ground source heat pump is mainly consumed by a water source heat pump unit, a submersible pump, a well water circulating pump, an air conditioner circulating pump and a tail end fan coil;
s32, calculating the loss of the ice storage air conditioning point, including the control of the ice storage temperature and the air supply temperature;
s33, calculating the electric loss of the electric heating boiler, wherein the electric loss of the electric heating boiler comprises the electric loss in the controller and the electric loss in the water pump; the efficiency of the electric boiler is
Figure RE-GDA0002399608310000071
wherein η is the efficiency of the electric boiler, eUser' sIs the electrical energy output to the user; w is input electric energy
S34, calculating the electrical loss of the water pump, wherein the electrical loss of the water pump mainly comprises the electrical losses of a boiler feed pump, a circulating water pump, a condensate lift pump, a drain pump, a mortar pump and a speed regulating oil pump, the water pump is reasonably configured, and the running speed of the water pump is properly adjusted to meet the requirement of load change.
Preferably, calculating the power loss of the energy storage system is calculating the charge and discharge loss of the distributed battery energy storage system, and for the charging condition, setting the charging efficiency of the ith distributed battery energy storage system as:
ηi,cha＝αi,cha-βi,cha·Pi,cha
wherein alpha isi,chaand betai,chaIs a charge constant; pi,chaFor charging power, Pi,cha>0 represents BESS input power [. eta. ]i,chaTo the charging efficiency;
internal power P of the distributed battery energy storage system during chargingi,bat,cha＝Pi,cha·ηi,cha. Setting the electricity price of a power grid as rho and the period as delta T, and setting the charging loss cost P of the distributed battery energy storage system per periodi,cha,lossIs defined as:
Pi,cha,loss＝ρ·Pi,cha·(1-ηi,cha)·ΔT
for the discharging condition, the discharging efficiency of the distributed battery energy storage system is set as follows:
ηi,dch＝αi,dch-βi,dch·Pi,dch
wherein alpha isi,dchand betai,dchIs the discharge constant; pi,dchFor discharge power, Pi,dch>0 represents BESS output power [. eta. ]i,dchThe discharge efficiency is obtained.
Internal power P of distributed battery energy storage system during dischargingi,bat,dch＝Pi,dch/ηi,dchDischarge loss cost per cycle Ci,dch,lossCan be defined as:
Figure RE-GDA0002399608310000081
preferably, electricity of the alternating current-direct current hybrid distributed system
Figure RE-GDA0002399608310000082
The efficiency is a comprehensive energy efficiency evaluation index of the alternating current-direct current hybrid distributed system, and the calculation formula is as follows,
Figure RE-GDA0002399608310000083
wherein eta isAC/DC，EIs system electricity
Figure RE-GDA0002399608310000084
Efficiency, PDThe electric quantity, P, delivered to the large gridsFor the total amount of thermal radiation received by the photovoltaic cell, PgTotal heat value of natural gas, P, for distributed combustion of natural gasBTotal heat value of hydrogen for fuel cell combustionAC/DC power supplyFor electricity of AC-DC power supply system
Figure RE-GDA0002399608310000085
Loss, piDistributed power generationElectricity for distributed generation systems
Figure RE-GDA0002399608310000086
Loss, piElectricity storageFor electricity of electricity storage systems
Figure RE-GDA0002399608310000087
Loss;
the AC/DC power supply system
Figure RE-GDA0002399608310000088
The efficiency is calculated by the formula
Figure RE-GDA00023996083100000813
wherein eta isEADFor electricity of AC-DC power supply system
Figure RE-GDA0002399608310000089
Efficiency, PJZFor the input power of the alternating current and direct current power supply system,
Figure RE-GDA00023996083100000810
respectively distribution line loss, power electronic transformer loss and rectifier loss, t in an AC/DC power supply system0、t1Starting and ending time of the current flowing for the AC/DC power supply system;
the distributed power generation system electricity
Figure RE-GDA00023996083100000811
The efficiency is calculated by the formula
Figure RE-GDA00023996083100000812
Wherein the content of the first and second substances,
Figure RE-GDA0002399608310000091
electricity for distributed generation systems
Figure RE-GDA0002399608310000092
Efficiency;
ΠCCHP＝Pg·Hs-Egasout
therein, IICCHPElectricity for natural gas distributed generation
Figure RE-GDA0002399608310000093
Loss, HsFor high calorific value of natural gas, EgasoutGenerating capacity for natural gas distributed power generation;
ΠTur-Gen＝m·h1-Eout
therein, IITur-GenFor electricity of turbines and generators
Figure RE-GDA0002399608310000094
Loss, m is the mass of steam fed to the turbine, h1To the enthalpy of the steam input to the turbine, EoutElectric energy output by the generator;
Figure RE-GDA0002399608310000095
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000096
loss of the photovoltaic distributed power generation system;
Figure RE-GDA0002399608310000097
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000098
for the depletion of the solar module, SpaAmount of heat radiation received for solar module, PoutOutputting power for the electric energy of the solar component;
Figure RE-GDA0002399608310000099
wherein the content of the first and second substances,
Figure RE-GDA00023996083100000910
in order to be a loss of the photovoltaic inverter,
Figure RE-GDA00023996083100000911
is the power loss of the inverter;
Figure RE-GDA00023996083100000912
Figure RE-GDA00023996083100000913
wherein, Δ PTFor active power loss, Δ QTFor reactive power loss, Δ P0、ΔQ0For no-load active and reactive power losses, Δ PS、ΔQSFor loading active power, reactive power, ScaFor real load power, SN.TRated capacity for the transformer;
the electricity storage system is electrically powered
Figure RE-GDA00023996083100000914
The efficiency is calculated by the formula
Figure RE-GDA00023996083100000915
Figure RE-GDA00023996083100000916
Figure RE-GDA00023996083100000917
Wherein the content of the first and second substances,
Figure RE-GDA00023996083100000918
for electricity of electricity storage systems
Figure RE-GDA00023996083100000919
Efficiency, PHThe total heating value of the hydrogen gas combusted for the fuel cell,
Figure RE-GDA00023996083100000920
in order to store the energy of the battery for the loss,
Figure RE-GDA0002399608310000101
is the depletion of the hydrogen fuel cell, eUser' sIs the electrical energy output to the user.
Preferably, the loss of the distribution line, the loss of the power electronic transformer and the loss of the rectifier in the AC/DC power supply system are respectively calculated by the following formulas,
Figure RE-GDA0002399608310000102
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000103
for loss of distribution line, Δ PLIn order to achieve a loss of line power,
Figure RE-GDA0002399608310000104
wherein, Δ PLFor line power loss, λ is power factor, U is line operating voltage, I is current flowing through the circuit, R is line resistance, ρ is line resistivity, l is line length, a is line cross-sectional area;
Figure RE-GDA0002399608310000105
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000106
in order to be a loss of the power electronic transformer,
Figure RE-GDA0002399608310000107
PHn、PEpower loss of each part of the power electronic transformer is achieved;
Figure RE-GDA0002399608310000108
wherein, PjnFor winding losses, Rn(1),Rn(2) Is the resistance of the primary and secondary windings under the nth harmonic,
Figure RE-GDA0002399608310000109
is the effective value of the harmonic current flowing through the primary winding and the secondary winding;
Figure RE-GDA00023996083100001010
Figure RE-GDA00023996083100001011
wherein, PHnFor hysteresis loss, PEFor eddy current losses, n is the harmonic order, UnIs an nth harmonic voltage, U1Is a fundamental voltage phinIs the initial phase angle of n-th harmonic voltage, s is the core material coefficient, BriIs the radial magnetic induction in the ith cell, BziIs the axial magnetic induction in the ith unit, omega is angular frequency, rho is material resistivity, b, d are wire dimensions, RiIs the distance from the center of gravity of the ith unit to the center line of the core, ViThe volume occupied by the conductor in the ith unit;
Figure RE-GDA00023996083100001012
wherein the content of the first and second substances,
Figure RE-GDA00023996083100001013
for losses of rectifiers, Pss、PSWPower loss for the power switch IGBT;
Figure RE-GDA00023996083100001014
PSW＝fPWM×(ESW(on)+ESW(off))
wherein, Pss、PSWFor power loss of the power switch IGBT, ICPIs the peak value of the sinusoidal output current, VCE(sat)Is the peak current ICPAnd D is the duty ratio, and theta is the power factor angle.
The invention has the beneficial effects that: 1. the invention improves the accuracy and efficiency of evaluating the electric loss and the energy consumption in the alternating current and direct current hybrid distributed system; the comprehensive energy loss rate in the distributed system is obtained by calculating various electric losses and heat losses in the distributed system so as to obtain the comprehensive energy loss rate in the distributed system
Figure RE-GDA0002399608310000111
And establishing an evaluation method as a parameter for evaluating the loss of the distributed system, and quantitatively analyzing the energy utilization efficiency of the distributed system. 2. The evaluation system is used for analyzing the alternating current-direct current hybrid distributed system, the accuracy and reliability of the calculation of the energy utilization rate of the distributed system can be effectively improved, the evaluation method can play a sufficient guiding role in the construction and operation processes of the distributed system, the income of the distributed system is improved, and the energy waste condition in the distributed system is reduced.
Drawings
FIG. 1 is a schematic flow chart of an evaluation method in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in FIG. 1, the present embodiment provides a method based on
Figure RE-GDA0002399608310000112
The alternating current-direct current hybrid distributed system comprises an alternating current-direct current power supply system, a distributed energy supply system, a thermodynamic system and an energy storage system; comprises the following steps of (a) carrying out,
s1, calculating the electric loss of the alternating current and direct current power supply system;
s2, calculating the electric loss of the distributed energy supply system;
s3, calculating the electric loss of the thermodynamic system;
s4, calculating the electric loss of the energy storage system;
s5, respectively obtaining the electric losses of the alternating current and direct current power supply system, the distributed function system, the thermodynamic system and the energy storage system according to the electric losses of the alternating current and direct current power supply system, the distributed function system, the thermodynamic system and the energy storage systemAnd electricity of the energy storage system
Figure RE-GDA0002399608310000113
Efficiency and ultimately the power of the AC/DC hybrid distributed system
Figure RE-GDA0002399608310000114
Efficiency.
In this embodiment, the step S1 specifically includes,
s11, calculating the line loss of the AC/DC power supply system;
s12, calculating the loss of the power electronic transformer;
s13, calculating the loss of the rectifier;
and S14, acquiring the electric loss of the alternating current and direct current power supply system according to the line loss, the loss of the power electronic transformer and the loss of the rectifier.
In this embodiment, the step S11 includes the following specific steps,
the reasons for line loss of electric energy during transmission include:
the resistance is used, and the lead of the circuit is mostly a conductor made of copper or aluminum material. When a current passes through it, it presents a resistance to the current, which is referred to as the resistance of the conductor. Electrical energy in the transmission of power networks, the resistance of the conductors must be overcome, resulting in a loss of electrical energy, which is seen in the heating of the conductors. Since this loss is caused by the resistance of the conductor, it is called resistive loss, which is proportional to the square of the current;
the reason of management is that the management of power supply and utilization management departments and related personnel is not strict enough, and leaks occur, so that the electric energy loss caused by illegal power utilization and electricity stealing of users, electric leakage of power grid elements, errors of electric energy metering devices, missing reading and wrong reading of meter reading personnel and the like is caused. The loss is not regular and is not easy to measure, so the loss is called as unknown loss. The unknown loss is generated in the business process of the power supply enterprise, so the unknown loss is also called business loss.
S111, calculating and counting line loss; the statistical line loss is calculated according to the electric energy meter index, the statistical line loss is the difference between the power supply quantity and the power selling quantity, and the calculation formula is that the statistical line loss is [ (power supply quantity-power selling quantity)/power supply quantity ] × 100%;
s112, calculating theoretical line loss; the theoretical line loss is calculated theoretically according to parameters of power supply equipment, the current running mode of the power grid, the current distribution and the load condition;
s113, calculating the management line loss; the management line loss is the loss electric quantity generated by factors in management, and the calculation formula is that the management line loss is statistical line loss (actual line loss) -theoretical line loss;
s114, calculating economic line loss; the economic line loss is a line with fixed equipment conditions, the theoretical line loss is not a fixed numerical value, but changes along with the change of the size of a power supply load, and actually, a lowest line loss rate exists, the lowest line loss rate is called economic line loss, and the corresponding current is called economic current;
s115, calculating rated line loss; rated line loss is also called line loss index, and is a line loss index approved by the upper level after measurement and calculation according to the actual line loss of the power network and by combining the power network structure, load flow condition and loss reduction measure arrangement condition in the next assessment period;
and S116, adding the statistical line loss, the theoretical line loss, the management line loss, the economic line loss and the rated line loss to obtain the line loss of the alternating current and direct current power supply system.
In this embodiment, step S12 includes the following specific steps,
the reasons for the point loss of the power electronic transformer include:
the resistance acts as a conductor, and the transformer is a copper or aluminum material, as is the case with the wire. When a current passes through it, it presents a resistance to the current, which is referred to as the resistance of the conductor. Since this loss is caused by the resistance of the conductor, it is called resistive loss, which is proportional to the square of the current. Losses in the transformer winding, also commonly referred to as copper losses;
under the action of the magnetic field, the transformer needs to establish and maintain an alternating magnetic field to boost or reduce the voltage. The process in which the current establishes a magnetic field in the electrical device, i.e. the electromagnetic transformation process. In this process, hysteresis and eddy currents are generated in the iron core of the electrical device due to the alternating magnetic field, causing the iron core to heat, thereby generating an electrical energy loss. Since such losses are generated during the electromagnetic conversion process, they are referred to as excitation losses, which cause the core to heat, also commonly referred to as core losses.
The capacity of a single transformer is increased day by day, the voltage level is increased, the internal structure of a large power transformer is more complex, and the problem of electric energy loss is more prominent. The calculation of the loss of the power electronic transformer is divided into two categories of harmonic consideration and harmonic non-consideration.
S121, calculating hysteresis loss of the power electronic transformer; the magnetizing speed of the ferromagnetic substance lags behind the changing speed of the external magnetic field in the magnetizing process of the iron core material, so that hysteresis phenomenon is generated, and the process can bring energy loss, namely hysteresis loss. The ferromagnetic material has a tendency of keeping the magnetism of the ferromagnetic material, when the ferromagnetic body is magnetized to a saturation state, the magnetic field intensity is gradually reduced, the magnetic induction intensity B at the moment is reduced along a path which is a section of higher magnetic induction intensity curve than the magnetic field intensity when the magnetic field intensity is enhanced, when the magnetic field intensity is reduced to zero, because the magnetic induction change in the magnet has certain hysteresis quality relative to the magnetic field intensity, the magnetic induction intensity at the moment is not equal to zero, namely, the relation between the magnetic field intensity and the magnetic flux density presents a closed curve of a hysteresis loop. In order to overcome the magnetic coercive force of the iron core, when the iron core is continuously magnetized by an alternating-current magnetic field, the hysteresis loss corresponding to the area of a hysteresis loop is generated in the iron core per unit area of cycle. This loss will be dissipated as heat energy into the surrounding medium, causing the transformer to increase in temperature and decrease in efficiency.
The hysteresis loss frequency is proportional to the second power of the hysteresis coefficient of the maximum magnetic flux density, and the loss caused by hysteresis under harmonic conditions can be expressed as,
Figure RE-GDA0002399608310000141
wherein, PHnFor hysteresis losses, n is harmonic orderNumber, UnIs an nth harmonic voltage (V), U1Is the fundamental voltage (V), phinIs the initial phase angle (degree) of the n-th harmonic voltage, and s is the coefficient of the iron core material; the above equation shows that the magnitude of the hysteresis loss is inversely proportional to the fundamental voltage, proportional to the harmonic voltage, proportional to the power factor, and related to the core material coefficient, the higher the harmonic voltage, the larger the power factor, the larger the hysteresis loss.
S122, calculating the eddy current loss of the power electronic transformer; when the alternating magnetic lines of force pass through the conductor, an induced electromotive force is generated in the conductor, and under the action of the induced electromotive force, a loop current is generated in the conductor to heat the conductor, which is called an eddy current. The loop current generated by the transformer is not output as energy, but is lost in the conductor of the transformer, so that the eddy current loss is generated. The eddy current loss in the core is proportional to the square of the magnetic flux density, the square of the frequency, and the square of the sheet thickness, and inversely proportional to the resistivity of the material. In practice, the distribution of the magnetic flux density in the core is not uniform, and due to the demagnetization caused by eddy currents, the magnetic field strength is lowest at the center of the core, increases from the center outwards, and is highest at the edges. Due to the law of electromagnetic induction, a change in the magnetic flux of the core will cause eddy currents to be generated in the core.
The eddy current loss is the loss caused by eddy current in the iron core, the leakage magnetic field in the transformer is divided into an axial leakage magnetic field and a radial leakage magnetic field, the loss caused by the induction intensity is also divided into an axial eddy current loss and a radial eddy current loss, the calculation formula is as follows,
Figure RE-GDA0002399608310000142
wherein, BriIs the radial magnetic induction intensity (T), B in the ith cellziThe axial magnetic induction intensity (T) in the ith unit, omega is angular frequency (Hz), rho is material resistivity (omega. m), b and d are wire sizes, RiIs the distance (mm) from the center of gravity of the ith unit to the center line of the iron core, ViThe volume occupied by the conductor in the ith cell (mm 3);
s123, calculating the winding loss of the power electronic transformer; the winding losses, also called copper losses or variable losses, consist of basic copper losses and additional copper losses. The loss caused by the direct current resistance of the primary and secondary side winding coils of the transformer is called basic copper loss; the effective resistance of the lead wire is increased due to the skin effect and the proximity effect caused by the leakage magnetic field, additional copper loss is generated to increase the copper loss, and the additional copper loss also comprises eddy current loss generated by the wall of the oil tank and the metal structural member, internal circulating current loss generated by the parallel winding of the lead wire and the like.
The winding loss consists of basic copper loss and additional copper loss, the loss caused by the direct current resistance of a winding coil at the primary side and the secondary side of the transformer is called as basic copper loss, the effective resistance of a lead can be increased to generate the additional copper loss due to the skin effect and the proximity effect caused by a leakage magnetic field, the additional copper loss also comprises the eddy current loss generated by the wall of an oil tank and a metal structural member and the internal circulating current loss generated by the parallel winding of the lead, under the direct current magnetic biasing effect, the calculation formula of the winding loss is as follows,
Figure RE-GDA0002399608310000151
wherein, PjnIs the winding loss (W), Rn(1)、Rn(2) Is the resistance (omega) of the primary winding and the secondary winding under the nth harmonic,
Figure RE-GDA0002399608310000152
is the effective value (I) of the harmonic current flowing through the primary and secondary windings;
and S124, adding the hysteresis loss, the eddy current loss and the winding loss to obtain the loss of the power electronic transformer.
In this embodiment, the three-phase voltage-type PWM rectifier is widely applied in the industry, so this is taken as an example. For the most commonly used power switch IGBT, the conduction and switching losses are the most dominant sources of losses in operation, and the step S13 includes the following specific contents,
s131, calculating average conduction loss; when an IGBT is in the on state and conducts current, the product of the on saturation voltage and the on current creates an on loss. For the IGBT controlled by the PWM method, the conduction loss must be multiplied by the duty factor to obtain the average loss.
When the rectifier is in an on state and conducts current, the product of the on state saturation voltage and the on state current forms conduction loss, the conduction loss must be multiplied by a duty factor to obtain average loss, and referring to an IGBT module manual, the steady state conduction loss of a single IGBT is as follows,
Figure RE-GDA0002399608310000153
wherein, PSSTo average conduction loss, ICPIs the peak value of the sinusoidal output current; vCE(sat)Is the peak current ICPThe saturation voltage drop of the lower IGBT; d is the duty cycle; theta is a power factor angle; due to saturation voltage drop V of each IGBT moduleCE(sat)All are different, so in order to reduce the conduction loss, when selecting the power module, VCE(sat)Are the parameters of significant concern.
S132, calculating average switching loss; the switching loss is power loss during the transition process of switching on and switching off the tube, and is measured by measuring I during the transition process of switching on and off according to the voltage and current oscillogram during the switching on and off processCAnd VCAnd multiplying the waveforms point-by-point to obtain the instantaneous waveform of the power, wherein the area under the power waveform is the switching energy in joules/pulse.
The average switching loss is obtained by multiplying the unit pulse total switching energy by the PWM frequency,
PSW＝fPWM×(ESW(on)+ESW(off))
wherein, PSWTo average switching losses, fPWMTo the PWM frequency, ESW(on)And ESW(off)The energy of the unit pulse main switch when the switch is opened and closed can be searched on a switch curve of a module manual according to expected working current, and the calculated value can be used as a preliminary estimation.
In this embodiment, the distributed energy supply system includes a combined cooling heating and power system and a distributed photovoltaic device; the step S2 includes the following specific contents,
in the combined cooling heating and power system, if the prime mover generates more electric energy than the electric power demand of the user, the electric energy is lost. The steam turbine is also equipment with higher energy consumption in a combined cooling heating and power system, and mainly consumes energy of the steam turbine unit, because the operating energy consumption of the steam turbine is increased when the vacuum of the air-cooled condenser is too high, the temperature of cooling water in the unit is higher and the actual operating load exceeds a specified parameter in the aspect of the operating and running of the steam turbine unit. The electricity consumption of the combined cooling heating and power system is reflected by the electrical efficiency and the energy gradient utilization.
S21, reflecting the power consumption of the combined cooling heating and power system through electric efficiency and energy cascade utilization; respectively calculating equivalent electric efficiency, reduced electric efficiency, energy cascade utilization rate and energy saving rate of the combined cooling heating and power system;
compared with the heat quantity, the cold quantity and the electric quantity, the electric quantity has the highest quality, but the heat quantity, the cold quantity and the electric quantity have equivalence. The equivalent electric quantity is the electric quantity consumed by respectively converting the cold quantity or the heat quantity in the combined supply system into the same cold quantity or the same heat quantity output by the corresponding conventional system, the equivalent electric efficiency is the ratio of the equivalent electric quantity to the primary energy consumption of the combined cooling and heating system, the equivalent electric quantity is the electric quantity consumed by respectively converting the cold quantity or the heat quantity in the combined cooling and heating system into the same cold quantity or the same heat quantity output by the corresponding conventional system, and the equivalent electric efficiency is calculated as follows,
Figure RE-GDA0002399608310000161
wherein eta is1For equivalent electric efficiency, COPhThe heat supply coefficient of the electric heat pump; it can be seen that the weight of cold and heat is related to the performance of the conventional system producing a reference for cold and heat, and that the efficiency of the electrically powered heat pump and the electric chiller of the conventional system has a large impact on the result of equivalent electrical efficiency. With the technological progress, the efficiency of the electric heat pump and the electric refrigerator of the conventional system will be improved, and the cold and heat are more easily obtained, so that the cold and heat are more easily obtainedThe weighting factor of the quantity is decreased.
The converted power generation efficiency of the combined cooling heating and power system enables the assumed energy consumption of the cooling capacity and the heat output in the system to be the same as that of the referenced separate production system, and the power generation efficiency is calculated. The heat supply efficiency of the production-dividing system adopts the heat supply efficiency of a boiler, the refrigeration efficiency adopts the refrigeration efficiency of an electric refrigerator, the calculation formula is as follows,
Figure RE-GDA0002399608310000171
wherein eta is2The reduced electrical efficiency.
The energy cascade utilization rate comprehensively considers the performance of the cold, heat and electricity products from the perspective of energy taste and cascade utilization, expresses the inequivalence of different products by taking the uniformly quantized energy level taste coefficients as the weight coefficients of cold, heat and electricity, considers the quantity and grade of consumed energy and the change condition along with the change of comparison conditions, and has the calculation formula as follows,
Figure RE-GDA0002399608310000172
Figure RE-GDA0002399608310000173
wherein eta is3The energy step utilization rate; a. theeEnergy level taste coefficient of electricity; a. thehIs the thermal energy level taste coefficient; a. thecIs the thermal energy level taste coefficient; a. thefIs the energy level taste coefficient of the fuel; delta E is an energy transfer process
Figure RE-GDA0002399608310000174
(ii) a change; Δ H is the enthalpy change during energy transfer; the energy gradient utilization rate comprehensively balances the essential difference of different energy conversion and utilization processes from the energy consumption taste in the processes of power generation, refrigeration, heat supply and the like and the quality of produced products and the like, better distinguishes the quantity and the quality of energy consumption, better distinguishes the inequivalence of cold and heat, and also better distinguishes the inequivalence of cold and heatThe heat supply difference of different temperatures is reflected.
The energy saving rate is a heat economy analysis method established on the basis of a first thermodynamic law, the energy saving condition of the combined cooling heating and power system is evaluated, and the combined cooling heating and power system is evaluated relative to the primary energy saving rate of a combined cooling heating and power system (power grid supply, boiler heating and cooling of an electric refrigerator) in a heating period or a cooling period under the condition of supplying the same heat, cooling and electric quantity; the energy-saving rate calculation formulas of the heating period and the cooling period are respectively as follows,
Figure RE-GDA0002399608310000181
Figure RE-GDA0002399608310000182
wherein eta iszhfor saving energy during the heating period etazcis the energy saving rate of the cooling period etaeefficiency of power supply for combined supply [. eta. ]hefficiency of heat supply for combined supply ηbThe heat supply efficiency of the boiler is improved; COPaThe refrigeration coefficient of the absorption refrigerator; COPeis the refrigeration coefficient of the electric refrigerator, and can be seen in the parameter (eta) of the sub-supply systemce、ηb、COPe) Under certain conditions, the energy saving rate of the combined cooling heating and power system in the heating period is improved along with the improvement of the power generation efficiency and the heating efficiency of the combined supply system, and the energy saving rate in the cooling period is improved along with the improvement of the power generation efficiency, the heating efficiency and the cooling efficiency of the absorption type refrigerating machine of the combined supply system. Along with the improvement of the refrigeration coefficient of the electric refrigerator and the power supply efficiency of the power grid, the energy saving rate of the combined cooling heating and power system is gradually reduced, even the energy is not saved. The energy saving rate of the combined cooling heating and power system is greatly related to the parameters of the separate supply system, the obtained results have difference under different power grid power supply efficiencies, boiler heat supply efficiencies and electric refrigerator efficiencies, and the energy saving rate is the same as the traditional heat efficiency and has no quality difference of distinguishing cold energy, heat energy and electricity energy.
S22, calculating the electrical part loss of the photovoltaic distributed equipment, including the reactive loss of the transformer and the influence of the overall efficiency of the inverter;
along with the increase of the capacity of the photovoltaic power station, the reactive loss in the photovoltaic power station is gradually increased, and further the active loss in the photovoltaic power station and the active loss of a power transmission line are increased. The reactive requirements of the grid-connected photovoltaic power station mainly come from a photovoltaic inverter, a boosting transformer, a power transmission line and a grid-connected main transformer. The reactive loss of the transformer occupies the main part during the day power generation, and the charging power of the transmission cable possibly occupies the main part during the night power outage. There are 2 types of transformers in a photovoltaic power plant, and 1 type is a double split step-up transformer connected to a photovoltaic inverter, and the voltage class is usually 35 kV. The other 1 is a boosting main transformer before grid connection of a photovoltaic power station, and the voltage grade is the same as that of a power grid, and is usually 110 kV.
The reactive loss of the transformer comprises no-load reactive loss and load reactive loss, the calculation formula is as follows,
QT＝QO.T+QP.T
Figure RE-GDA0002399608310000191
Figure RE-GDA0002399608310000192
wherein Q isTFor reactive losses of transformers, QO.TFor no-load reactive losses, i.e. fixed losses, QP.TFor carrying reactive losses, Ud% is the short-circuit voltage percentage of the transformer; i isOT% is the no-load current percentage of the transformer; sN.TRated capacity for the transformer; sTIs the actual load of the transformer; pPVIs the photovoltaic power transmitted by the transformer; the photovoltaic power change will cause the reactive loss to change dramatically, i.e. the photovoltaic power change by 1 time, will cause the reactive loss to change by 2 times. Because solar energy changes greatly day and night, at night, the transformer is in an idle state because the photovoltaic active output is 0, and therefore the reactive loss of the photovoltaic power station is greatly different in day and night.
For a high power inverter, the operating efficiency must reach 90% or above 95% when the inverter is fully loaded. In particular at low load power supply, a relatively high efficiency is still required. Meanwhile, the efficiency of the inverter directly affects the effective power generation amount and the power generation cost of the photovoltaic power generation system. In addition, the inverter applied to the photovoltaic power generation system has to reduce the power loss per se to a certain extent in the design process, and the efficiency of the whole machine is effectively improved. The main reason is that the practical working efficiency of the general inverter of 10kV level is only 70% to 80%, and when the general inverter is applied to a photovoltaic power generation system, the electric energy consumption of 20% to 30% of the total power generation amount is caused. Therefore, in order to improve the output efficiency, the grid-connected inverter should be ensured to have the tracking control management function of the maximum power point, and can be changed along with the corresponding change of the radiation capacity of the solar energy at any time. And automatic on and off can be realized according to the difference of conditions such as sunrise and sunset.
In this embodiment, the step S3 includes the following specific steps,
s31, calculating heat pump electric losses including the electric losses of the air source heat pump system and the water source heat pump system;
when the air source heat pump water heater is heated to a higher water temperature, the power consumption of the system obviously rises, the system power consumption is increased by a large amount of air suction liquid, the system performance (COP) is reduced, and the power consumption is increased. In order to clarify the power consumption condition of the air source heat pump system in a complete heating (frosting)/defrosting (regenerating) period under the same heating quantity requirement and the same working condition of the outdoor side and the user side, a performance model is required to be established.
The heating and defrosting (regeneration) processes of the heat pump system are non-steady-state processes, and therefore the overall performance of the heat pump system should be described in terms of one heating/defrosting cycle. If the air source heat pump system is specified to supply heat to the indoor in the heating stage as positive, and to take heat from the indoor in the defrosting stage as positive, the energy conservation equation of the air source heat pump system is listed,
a. the heat production (frosting) process has the energy conservation equation as follows,
Qi1＝W1+Qo1
Qo1＝Qo1,s+Qo1,l
wherein Q iso1,sFor sensible heat of the frosting process, Qo1,lLatent heat for the frosting process;
b. in the defrosting (regeneration) process, the air source heat pump system can take heat from a user side and can also take heat from other channels to provide heat required by the defrosting (regeneration) process, the energy conservation equation is,
Qo2＝W2+Qi2
Qo2＝Qo2,s+Qo2,l
wherein Q iso2,sFor sensible heat of the frosting process, Qo2,lLatent heat for the frosting process;
c. actual heating quantity Q of air source heat pump system to user side in one heating/defrosting periodhIn order to realize the purpose,
Qh＝Qi1-Qi2
d. energy efficiency ratio COP of air source heat pump system in frosting/defrosting periodsIn order to realize the purpose,
Figure RE-GDA0002399608310000201
the compressor, the water source pump and the circulating pump in the water source heat pump system are main power consumption equipment.
The compressor belongs to a constant torque load, and is characterized in that the resistance torque T of the load is basically constant under different rotating speeds n of the dragging motor, namely T is constant, and the resistance torque T of the load is independent of the high and low rotating speeds n. The relation between the power P of the load and the torque T and the rotating speed n is as follows: when the rotating speed is n1, the consumed power is P1 when P is Tn/9550; when the rotation speed is n2, the consumed power is P2. Then: P1/P2 ═ n1/n2, when n1 is the rated speed, P1 is the rated power consumed. That is to say, when the compression type circulating water unit utilizes the frequency converter to control the electric motor to carry out speed regulation, the energy consumption is large when the working frequency is increased, and the percentage of the increased frequency is the percentage of the increased power. Theoretically, the electrical loss is still very large.
The water pump belongs to quadratic load. The torque resistance T of the load is proportional to the square of the speed n, i.e., T is KTn 2. In the formula, KT is a torque constant of a quadratic load. The relation between the power P of the load and the rotating speed n is as follows: and P is Tn/9550 is KPn. In the formula, KP is a power constant of a quadratic load. The above equation shows that the power consumed by the water pump is proportional to its speed cube. When the frequency converter is used for controlling the water pump to operate, the output frequency of the frequency converter is f1, the rotating speed of the water pump is n1, the flow rate is Q1, and the shaft power of a water pump motor is P1; the output frequency of the frequency converter is f2, the rotating speed of the water pump is n2, the flow rate is Q2, and the shaft power of the water pump motor is P2; then Q is1:Q2＝1n:2n， Q1:Q2＝n1:n2I.e. the power consumed by the motor is proportional to the 3 rd power of its rotational speed; it can be seen that the power consumed by the motor is proportional to the rotational speed of the motor to the power of 3, and a large amount of electric energy is consumed when the rotational speed is increased. Therefore, when the water flow required by the water source heat pump system is increased, the rotating speed of the motor is increased, and the consumed energy is obviously increased.
The power consumption of a ground source heat pump system is mainly the consumption of equipment such as a water source heat pump unit, a submersible pump, a well water circulating pump, an air conditioner circulating pump, a tail end fan coil and the like, in addition, the matching of all water pump systems is more important in the underground water ground source heat pump system, the power consumption of the system is influenced, the stable operation of the system is also related sometimes, and the reasonable matching between a deep well pump and the circulating pump is particularly important.
S32, calculating the loss of the ice storage air conditioning point, including the control of the ice storage temperature and the air supply temperature;
when the ice storage air-conditioning system stores ice, the temperature of an ice water outlet end of the refrigerator is generally required to be lower than minus 5 ℃, so that the evaporation temperature and the pressure of the refrigerator are reduced; on the other hand, because the cold is charged at night, the condensing temperature is lower than that in the daytime, the influence caused by the reduction of a little evaporating temperature can be compensated, in short, the refrigerating capacity of the refrigerator is reduced during cold storage, and the power consumption of unit cold quantity is increased;
if the air supply temperature of the air conditioning system is high, the air supply quantity under the same cold load is increased, so that the power consumed by the running of the fan is increased, the energy consumption of the system is larger, and the running cost is increased. The power consumed by the fan can be raised in a cubic manner along with the increase of the air supply quantity according to the power formula of the hydrodynamics fan. Further, an increase in the amount of air blown means an increase in the size of the air blowing duct, resulting in an increase in the initial investment of the system. Therefore, the power consumption of the ice storage air conditioning system is increased due to the increase of the air supply temperature.
S33, calculating the electric loss of the electric heating boiler, wherein the electric loss of the electric heating boiler comprises the electric loss in the controller and the electric loss in the water pump; the efficiency of the electric boiler is
Figure RE-GDA0002399608310000211
wherein η is the efficiency of the electric boiler, eUser' sIs the electrical energy output to the user; w is the input electric energy.
S34, calculating the electrical loss of the water pump, wherein the electrical loss of the water pump mainly comprises the electrical losses of a boiler feed pump, a circulating water pump, a condensate lift pump, a drain pump, a mortar pump and a speed regulating oil pump, the water pump is reasonably configured, and the running speed of the water pump is properly adjusted to meet the requirement of load change.
The water pump is the most power consuming device in the power plant. In a thermal power plant, the power consumption of the water pump accounts for about 40% of the power consumption of the plant. Among them, a boiler feed pump, a circulating water pump, a condensate lift pump, a drain pump, a mortar pump, a speed-adjusting oil pump, and the like are most important. 1 30-ten-thousand-kW thermal power generator set needs to be provided with more than 80 pumps of various types, the installation power is about 1.8-thousand-kW, the annual power consumption is nearly 1 hundred million kW.h, and the power consumption accounts for 4-5% of the power generation capacity of the whole plant. Wherein, 2 boiler water feeding pumps, 5600 kW single machines, 3 circulating water pumps and 1100kW single machines are adopted; 2 condensing pumps with 550kW single pump. The pumps are large in installation power and long in running time, and the power consumption accounts for more than 80% of that of the water pumps of the thermal power plant.
Unreasonable matching and large abundant capacity; the water pump in the power plant is selected and matched according to the maximum load of the boiler and the steam turbine. From the viewpoint of operation safety, the capacity of the slave is generally selected to be larger than that of the master. If the capacity of the boiler water supply pump can meet that the rated water supply quantity of the boiler is 1.1 times, the capacity of the boiler is required to be larger than the output of a steam turbine, and the output of the steam turbine is required to be larger than the output of a generator, the stacking is carried out layer by layer, so that the design output of a fan water pump of a power plant is about 20-30% larger than that of the actual operation. Some methods also consider the influence of system resistance change, equipment abrasion, leakage, flow, pressure and the like on the allowance, so that the output of some power plant water pumps is more than 30% of the actual output, and the power consumption is greatly increased.
The constant-speed operation is not suitable for the requirement of load change; in order to meet the peak shaving requirement of the power system, the load of the power plant is generally in a variable state, and particularly, the load of some generator sets which are used for peak shaving operation has a large load change amplitude, and some generator sets can reduce the load from 100% to 60% or even lower. The fan and the water pump matched with the fan and the water pump are adjusted correspondingly, so that the requirements of the host machine are met. Because most of water pumps run at a constant speed, the load of the water pumps is inconvenient to adjust, and the flow and the pressure are generally controlled by adjusting the opening of a valve, so that great throttling loss is caused, and a large amount of electric energy is wasted.
The operation is throttled, and the waste of electric energy is large; high and medium pressure units put into production in the early stage of thermal power plants in China generally adopt a main pipe system for water supply, a water pump runs at a constant speed, and throttling regulation is carried out. When the boiler feed water quantity requirement changes greatly, the requirement is met by changing the number of running water pumps and matching with valve adjustment; if the water supply quantity demand change is small, the opening degree of the valve is changed for adjustment. By the 70 s of the 20 th century, particularly large and medium-sized thermal power generating units of more than 100MW, unit system systems are generally adopted, namely 1 boiler is specially supplied by 1 or 2 feed pumps, and the boiler still runs at a constant speed. When the water pump runs at full load, 1 water pump can not meet the requirement; 2 water feeding pumps are adopted for supplying water, the pressure and the flow are rich, and the requirement of load change can be met only by adopting throttling regulation, so that great throttling loss is caused. If the annual load of the 200MW thermal power generating unit is 180MW, the throttling loss generated on the valve of the feed water pump reaches 8840MW & h. According to the test of relevant departments, when 1 centrifugal water pump with 40kW runs at 70% of rated flow, the power loss caused by throttling is as high as about 15kW, which is equivalent to 30% -40% of the input power of a motor.
In this embodiment, calculating the electrical loss of the energy storage system is calculating the charge and discharge loss of the distributed Battery Energy Storage System (BESS),
for the charging situation, the charging efficiency of the ith distributed battery energy storage system is set as follows:
ηi,cha＝αi,cha-βi,cha·Pi,cha
wherein alpha isi,chaand betai,chaIs a charge constant; pi,chaFor charging power, Pi,cha>0 represents BESS input power [. eta. ]i,chaTo the charging efficiency;
internal power P of the distributed battery energy storage system during chargingi,bat,cha＝Pi,cha·ηi,chaSetting the electricity price of a power grid as rho and the period as delta T, and setting the charging loss cost P of the distributed battery energy storage system per periodi,cha,lossIs defined as:
Pi,cha,loss＝ρ·Pi,cha·(1-ηi,cha)·ΔT
for the discharging condition, the discharging efficiency of the distributed battery energy storage system is set as follows:
ηi,dch＝αi,dch-βi,dch·Pi,dch
wherein alpha isi,dchand betai,dchIs the discharge constant; pi,dchFor discharge power, Pi,dch>0 represents BESS output power [. eta. ]i,dchThe discharge efficiency is obtained.
Internal power P of distributed battery energy storage system during dischargingi,bat,dch＝Pi,dch/ηi,dchDischarge loss cost per cycle Ci,dch,lossCan be defined as:
Figure RE-GDA0002399608310000231
summarizing the distribution situation of the electricity/heat loss of the alternating current-direct current hybrid distributed system:
Figure RE-GDA0002399608310000232
Figure RE-GDA0002399608310000241
energy efficiency evaluation index system of AC/DC hybrid distributed system:
and constructing an integrated energy efficiency evaluation index system facing the alternating current-direct current hybrid distributed system according to the target layer, the system layer, the equipment layer and the element index layer.
Figure RE-GDA0002399608310000251
In this embodiment, electricity of the ac/dc hybrid distributed system
Figure RE-GDA0002399608310000252
The efficiency is a comprehensive energy efficiency evaluation index of the alternating current-direct current hybrid distributed system, and the calculation formula is as follows,
Figure RE-GDA0002399608310000253
wherein eta isAC/DC，EIs system electricity
Figure RE-GDA0002399608310000254
Efficiency, PDThe electric quantity, P, delivered to the large gridsFor the total amount of thermal radiation received by the photovoltaic cell, PgTotal heat value of natural gas, P, for distributed combustion of natural gasBTotal heat value of hydrogen for fuel cell combustion, IIAC/DC power supplyFor electricity of AC-DC power supply system
Figure RE-GDA0002399608310000255
Loss, piDistributed power generationElectricity for distributed generation systems
Figure RE-GDA0002399608310000256
Loss, piElectricity storageFor electricity of electricity storage systems
Figure RE-GDA0002399608310000257
Loss; electricity of system
Figure RE-GDA0002399608310000258
The larger the efficiency value is, the higher the energy utilization efficiency of the alternating current-direct current hybrid distributed system is.
The AC/DC power supply system
Figure RE-GDA0002399608310000259
The efficiency is calculated by the formula
Figure RE-GDA00023996083100002510
Wherein the content of the first and second substances,
Figure RE-GDA00023996083100002511
for electricity of AC-DC power supply system
Figure RE-GDA00023996083100002512
Efficiency, PJZFor the input power of the alternating current and direct current power supply system,
Figure RE-GDA0002399608310000261
respectively distribution line loss, power electronic transformer loss and rectifier loss, t in an AC/DC power supply system0、t1And starting and ending the current flowing of the AC/DC power supply system.
The loss of a distribution line, the loss of a power electronic transformer and the loss of a rectifier in the alternating current and direct current power supply system are respectively calculated by the following formulas.
Loss of the distribution circuit:
Figure RE-GDA0002399608310000262
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000263
for loss of distribution line, Δ PLIs the line power loss.
Power loss of the distribution line:
Figure RE-GDA0002399608310000264
wherein, Δ PLFor line power loss, λ is the power factor, U is the line operating voltage, I is the current flowing through the circuit, R is the line resistance, ρ is the line resistivity, l is the line length, and a is the line cross-sectional area.
Loss of the power electronic transformer:
Figure RE-GDA0002399608310000265
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000266
in order to be a loss of the power electronic transformer,
Figure RE-GDA0002399608310000267
PHn、PEthe power loss of each part of the power electronic transformer is realized.
Winding power loss in a power electronic transformer in an alternating current-direct current hybrid distributed system:
Figure RE-GDA0002399608310000268
wherein, PjnFor winding losses, Rn(1),Rn(2) Is the resistance of the primary and secondary windings under the nth harmonic,
Figure RE-GDA0002399608310000269
is the effective value of the harmonic current flowing through the primary and secondary windings.
The power loss of the iron core in the power electronic transformer in the alternating current-direct current hybrid distributed system contains two parts, namely hysteresis loss and eddy current loss. The power loss of the core is:
Figure RE-GDA00023996083100002610
Figure RE-GDA00023996083100002611
wherein, PHnFor hysteresis loss, PEFor eddy current losses, n is the harmonic order, UnIs an nth harmonic voltage, U1Is a fundamental voltage phinIs the initial phase angle of n-th harmonic voltage, s is the core material coefficient, BriIs the radial magnetic induction in the ith cell, BziIs the axial magnetic induction in the ith unit, omega is angular frequency, rho is material resistivity, b, d are wire dimensions, RiIs the distance from the center of gravity of the ith unit to the center line of the core, ViThe volume occupied by the conductor in the ith cell.
Loss of the rectifier:
Figure RE-GDA0002399608310000271
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000272
for losses of rectifiers, Pss、PSWIs the power loss of the power switch IGBT.
The power loss of a power switch IGBT in a rectifier in an alternating current-direct current hybrid distributed system is as follows:
Figure RE-GDA0002399608310000273
PSW＝fPWM×(ESW(on)+ESW(off))
wherein, Pss、PSWFor power loss of the power switch IGBT, ICPIs the peak value of the sinusoidal output current, VCE(sat)Is the peak current ICPAnd D is the duty ratio, and theta is the power factor angle.
The distributed power generation system electricity
Figure RE-GDA0002399608310000274
The efficiency is calculated by the formula
Figure RE-GDA0002399608310000275
Wherein the content of the first and second substances,
Figure RE-GDA0002399608310000276
electricity for distributed generation systems
Figure RE-GDA0002399608310000277
Efficiency.
ΠCCHP＝Pg·Hs-Egasout
Therein, IICCHPElectricity for natural gas distributed generation
Figure RE-GDA0002399608310000278
Loss, HsFor high calorific value of natural gas, EgasoutThe power generation capacity of natural gas distributed power generation is obtained.
Electricity for steam turbine and generator in natural gas distributed power generation system
Figure RE-GDA0002399608310000279
The loss, defined as:
∏Tur-Gen＝m·h1-Eout
therein, IITur-GenFor electricity of turbines and generators
Figure RE-GDA00023996083100002710
Loss, m is the mass of steam fed to the turbine, h1To the enthalpy of the steam input to the turbine, EoutThe electric energy is output by the generator.
Photovoltaic distributed power generation
Figure RE-GDA00023996083100002711
Loss:
Figure RE-GDA00023996083100002712
wherein the content of the first and second substances,
Figure RE-GDA00023996083100002713
loss of the photovoltaic distributed power generation system.
The generation efficiency of the photovoltaic system is closely related to the photoelectric conversion efficiency of the solar cells which are components of the photovoltaic power station, in general the conversion efficiency of single crystal salicide cells is 17-22%, the polygamy baby is 16% -19% and the amorphous salicide is 6% -10%. On the other hand, the output characteristics of the photovoltaic module can change along with the changes of the radiation intensity and the temperature, when the air temperature and the box radiation amount are too high, the output current of the photovoltaic cell is larger than the short-circuit current, the equivalent resistance and the voltage drop of the photovoltaic cell are very large like a diode working under reverse voltage, so that the power is consumed and the heating is caused, the local high temperature is caused to appear after the time is long, the hot spot is formed, the output performance of the photovoltaic module is seriously influenced, and the photoelectric conversion efficiency of the photovoltaic module under different geographic environments can also change accordingly. The loss of the solar module in the photovoltaic distributed power generation is as follows:
Figure RE-GDA0002399608310000281
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000282
for the depletion of the solar module, SpaAmount of heat radiation received for solar module, PoutAnd outputting power for the electric energy of the solar module.
The power loss of an inverter in photovoltaic distributed power generation mainly comprises the loss of other parts such as power electronic device loss, direct current side capacitance loss, filter loss and the like, and the loss of the photovoltaic inverter is defined as:
Figure RE-GDA0002399608310000283
wherein the content of the first and second substances,
Figure RE-GDA0002399608310000284
in order to be a loss of the photovoltaic inverter,
Figure RE-GDA0002399608310000285
is the power loss of the inverter. The inverter is an indispensable component as the heart of the photovoltaic system, and power loss also occurs in the inverter due to electronic devices and inductive elements
Figure RE-GDA0002399608310000286
Can be found by data parameters given by the manufacturer.
The loss of a transformer for photovoltaic distributed power generation in a distributed power generation system is defined as:
Figure RE-GDA0002399608310000287
Figure RE-GDA0002399608310000288
wherein, Δ PTFor active power loss, Δ QTFor reactive power loss, Δ P0、ΔQ0For no-load active and reactive power losses, Δ PS、ΔQSFor loading active power, reactive power, ScaFor real load power, SN.TThe rated capacity of the transformer.
The electricity storage system is electrically powered
Figure RE-GDA0002399608310000289
The efficiency is calculated by the formula
Figure RE-GDA00023996083100002810
Wherein the content of the first and second substances,
Figure RE-GDA00023996083100002811
for electricity of electricity storage systems
Figure RE-GDA00023996083100002812
Efficiency, PHThe total heating value of the hydrogen gas combusted for the fuel cell,
Figure RE-GDA00023996083100002813
is a loss of the energy storage battery.
Figure RE-GDA0002399608310000291
Is the depletion of the hydrogen fuel cell, eUser' sIs the electrical energy output to the user.
By adopting the technical scheme disclosed by the invention, the following beneficial effects are obtained:
the invention provides a method based on
Figure RE-GDA0002399608310000292
The method and the system for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system calculate various electric losses and heat losses in the system to obtain the comprehensive energy loss rate in the system so as to
Figure RE-GDA0002399608310000293
As a parameter for evaluating the system loss, establishing an index system and quantitatively analyzing the energy utilization efficiency of the system; the index system is utilized to analyze the alternating current-direct current hybrid distributed system, the accuracy and reliability of the calculation of the energy utilization rate of the distributed system can be effectively improved, the index system can play a sufficient guiding role in the construction and operation processes of the distributed system, the income of the distributed system is improved, and the energy waste condition in the distributed system is reduced; the accuracy and the efficiency of evaluating the electric loss and the energy consumption in the alternating current and direct current hybrid distributed system are improved.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements should also be considered within the scope of the present invention.

Claims (10)

1. Based on
Figure RE-FDA0002399608300000011
The alternating current-direct current hybrid distributed system comprises an alternating current-direct current power supply system, a distributed energy supply system, a thermodynamic system and an energy storage system; which is characterized by comprising the following steps of,
s1, calculating the electric loss of the alternating current and direct current power supply system;
s2, calculating the electric loss of the distributed energy supply system;
s3, calculating the electric loss of the thermodynamic system;
s4, calculating the electric loss of the energy storage system;
s5, respectively obtaining the electric losses of the AC/DC power supply system, the distributed function system, the thermodynamic system and the energy storage system according to the electric losses of the AC/DC power supply system, the distributed function system, the thermodynamic system and the energy storage system
Figure RE-FDA0002399608300000012
Efficiency and ultimately the power of the AC/DC hybrid distributed system
Figure RE-FDA0002399608300000013
Efficiency.
2. The method according to claim 1
Figure RE-FDA0002399608300000014
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: the step S1 specifically includes the steps of,
s11, calculating the line loss of the AC/DC power supply system;
s12, calculating the loss of the power electronic transformer;
s13, calculating the loss of the rectifier;
and S14, acquiring the electric loss of the alternating current and direct current power supply system according to the line loss, the loss of the power electronic transformer and the loss of the rectifier.
3. The method according to claim 2
Figure RE-FDA0002399608300000015
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: the step S11 includes the following specific contents,
s111, calculating and counting line loss; the statistical line loss is the difference between the power supply amount and the power selling amount, and the calculation formula is that the statistical line loss is [ (power supply amount-power selling amount)/power supply amount ] × 100%;
s112, calculating theoretical line loss; the theoretical line loss is calculated theoretically according to parameters of power supply equipment, the current running mode of the power grid, the current distribution and the load condition;
s113, calculating the management line loss; the management line loss is the loss electric quantity generated by factors in management, and the calculation formula is that the management line loss is statistical line loss (actual line loss) -theoretical line loss;
s114, calculating economic line loss; the theoretical line loss of a line with fixed equipment conditions changes along with the change of the electric load, the line loss rate is the lowest, the lowest line loss rate is the economic line loss, and the corresponding current becomes the economic current;
s115, calculating rated line loss; the rated line loss is a line loss index approved by a higher level through measurement and calculation according to the actual line loss of the power network and by combining the power network structure, the load flow condition and the loss reduction measure arrangement condition in the next assessment period;
and S116, adding the statistical line loss, the theoretical line loss, the management line loss, the economic line loss and the rated line loss to obtain the line loss of the alternating current and direct current power supply system.
4. The method according to claim 2
Figure RE-FDA0002399608300000021
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: step S12 includes the following specific contents,
s121, calculating hysteresis loss of the power electronic transformer; the hysteresis loss frequency is proportional to the second power of the hysteresis coefficient of the maximum magnetic flux density, and the loss caused by hysteresis under harmonic conditions can be expressed as,
Figure RE-FDA0002399608300000022
wherein, PHnFor hysteresis losses, n is the harmonic order, UnIs an nth harmonic voltage (V), U1Is the fundamental voltage (V), phinIs the initial phase angle (degree) of the n-th harmonic voltage, and s is the coefficient of the iron core material;
s122, calculating the eddy current loss of the power electronic transformer; the eddy current loss is the loss caused by eddy current in the iron core, the leakage magnetic field in the transformer is divided into an axial leakage magnetic field and a radial leakage magnetic field, the loss caused by the induction intensity is also divided into an axial eddy current loss and a radial eddy current loss, the calculation formula is as follows,
Figure RE-FDA0002399608300000023
wherein, BriIs the radial magnetic induction intensity (T), B in the ith cellziThe axial magnetic induction intensity (T) in the ith unit, omega is angular frequency (Hz), rho is material resistivity (omega. m), b and d are wire sizes, RiIs the distance (mm) from the center of gravity of the ith unit to the center line of the iron core, ViThe volume occupied by the conductor in the ith cell (mm 3);
s123, calculating the winding loss of the power electronic transformer; the winding loss consists of basic copper loss and additional copper loss, the loss caused by the direct current resistance of a winding coil at the primary side and the secondary side of the transformer is called as basic copper loss, the effective resistance of a lead can be increased to generate the additional copper loss due to the skin effect and the proximity effect caused by a leakage magnetic field, the additional copper loss also comprises the eddy current loss generated by the wall of an oil tank and a metal structural member and the internal circulating current loss generated by the parallel winding of the lead, under the direct current magnetic biasing effect, the calculation formula of the winding loss is as follows,
Figure RE-FDA0002399608300000031
wherein, PjnIs the winding loss (W), Rn(1)、Rn(2) Is the resistance (omega) of the primary winding and the secondary winding under the nth harmonic,
Figure RE-FDA0002399608300000032
is the effective value (I) of the harmonic current flowing through the primary and secondary windings;
and S124, adding the hysteresis loss, the eddy current loss and the winding loss to obtain the loss of the power electronic transformer.
5. The method according to claim 2
Figure RE-FDA0002399608300000034
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: the rectifier is controlled by PWM, and the step S13 includes the following details,
s131, calculating average conduction loss; when the rectifier is in the on state and conducts current, the product of the on state saturation voltage and the on state current forms the conduction loss, the conduction loss must be multiplied by the duty cycle factor to obtain the average loss, the average conduction loss of the rectifier is as follows,
Figure RE-FDA0002399608300000033
wherein, PSSTo average conduction loss, ICPIs the peak value of the sinusoidal output current; vCE(sat)Is the peak current ICPThe saturation voltage drop of the lower IGBT; d is the duty cycle; theta is a power factor angle;
s132, calculating average switching loss; the switching loss is the power loss during the transition process of switching on and switching off the tube, the average switching loss is obtained by multiplying the unit pulse total switching energy by the PWM frequency,
PSW＝fPWM×(ESW(on)+ESW(off))
wherein, PSWTo average switching losses, fPWMTo the PWM frequency, ESW(on)And ESW(off)The energy of the unit pulse master switch when the unit pulse master switch is opened and closed respectively.
6. The method according to claim 1
Figure RE-FDA0002399608300000035
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: the distributed energy supply system comprises a combined cooling heating and power system and photovoltaic distributed equipment; the step S2 includes the following specific contents,
s21, reflecting the power consumption of the combined cooling heating and power system through electric efficiency and energy cascade utilization; respectively calculating equivalent electric efficiency, reduced electric efficiency, energy cascade utilization rate and energy saving rate of the combined cooling heating and power system;
the equivalent electric efficiency is the ratio of the equivalent electric quantity to the primary energy consumption of the combined cooling, heating and power system, the equivalent electric quantity is the electric quantity consumed by the corresponding conventional system for outputting the same cooling or heating quantity respectively by converting the cooling or heating quantity in the combined cooling, heating and power system, the equivalent electric efficiency is calculated as follows,
Figure RE-FDA0002399608300000041
wherein eta is1For equivalent electric efficiency, COPhThe heat supply coefficient of the electric heat pump;
the reduced power generation rate is the power generation efficiency calculated when the energy consumption of cold output and the energy consumption of heat output in the cold-heat-electricity combined supply system are assumed to be the same as the conventional reference, the calculation formula is as follows,
Figure RE-FDA0002399608300000042
wherein eta is2Reduced electrical efficiency;
the energy cascade utilization rate comprehensively considers the performance of the cooling, heating and power products from the perspective of energy taste and cascade utilization, expresses the inequivalence of different products by taking uniformly quantized energy level taste coefficients as weight coefficients of cold, heat and power, considers the quantity and grade of consumed energy and the change condition along with the change of comparison conditions, and has the calculation formula as follows,
Figure RE-FDA0002399608300000043
Figure RE-FDA0002399608300000044
wherein eta is3The energy step utilization rate; a. theeEnergy level taste coefficient of electricity; a. thehIs the thermal energy level taste coefficient; a. thecIs the thermal energy level taste coefficient; a. thefIs the energy level taste coefficient of the fuel; delta E is an energy transfer process
Figure RE-FDA0002399608300000046
(ii) a change; Δ H is the enthalpy change during energy transfer;
the energy saving rate is a heat economy analysis method established on the basis of a first thermodynamic law, the energy saving condition of the combined cooling heating and power system is evaluated, and the combined cooling heating and power system is evaluated relative to the primary energy saving rate of the combined cooling heating and power system in the heating period or the cooling period under the condition of supplying the same heat, cooling capacity and electric quantity; the energy-saving rate calculation formulas of the heating period and the cooling period are respectively as follows,
Figure RE-FDA0002399608300000045
Figure RE-FDA0002399608300000051
wherein eta iszhfor saving energy during the heating period etazcis the energy saving rate of the cooling period etaeefficiency of power supply for combined supply [. eta. ]hefficiency of heat supply for combined supply ηbThe heat supply efficiency of the boiler is improved; COPaThe refrigeration coefficient of the absorption refrigerator; COPeThe refrigeration coefficient of the electric refrigerator;
s22, calculating the electrical part loss of the photovoltaic distributed equipment, including the reactive loss of the transformer and the influence of the overall efficiency of the inverter;
the reactive loss of the transformer comprises no-load reactive loss and load reactive loss, the calculation formula is as follows,
QT＝QO.T+QP.T
Figure RE-FDA0002399608300000052
Figure RE-FDA0002399608300000053
wherein Q isTFor reactive losses of transformers, QO.TFor no-load reactive power loss, QP.TFor carrying reactive losses, Ud% is the short-circuit voltage percentage of the transformer; i isOT% is the no-load current percentage of the transformer; sN.TRated capacity for the transformer; sTIs the actual load of the transformer; pPVIs the photovoltaic power transmitted by the transformer;
the efficiency of the inverter directly influences the effective generating capacity and the generating cost of the photovoltaic generating system, so that the inverter has the function of tracking control and management of the maximum power point and can change along with the corresponding change of the radiation capacity of solar energy at any time.
7. The method according to claim 1
Figure RE-FDA0002399608300000054
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: the step S3 includes the following specific contents,
s31, calculating heat pump electric losses including the electric losses of the air source heat pump system and the water source heat pump system;
the power consumption condition of the air source heat pump system in a complete heating (frosting)/defrosting (regenerating) period is defined as that the air source heat pump system supplies heat to the indoor in the heating stage as positive, heat is taken from the indoor in the defrosting stage as positive, an energy conservation equation of the air source heat pump system is listed,
a. the heat production (frosting) process has the energy conservation equation as follows,
Qi1＝W1+Qo1
Qo1＝Qo1,s+Qo1,l
wherein Q iso1,sFor sensible heat of the frosting process, Qo1,lLatent heat for the frosting process;
b. in the defrosting (regeneration) process, the air source heat pump system can take heat from a user side and can also take heat from other channels to provide heat required by the defrosting (regeneration) process, the energy conservation equation is,
Qo2＝W2+Qi2
Qo2＝Qo2,s+Qo2,l
wherein Q iso2,sFor sensible heat of the frosting process, Qo2,lLatent heat for the frosting process;
c. actual heating quantity Q of air source heat pump system to user side in one heating/defrosting periodhIn order to realize the purpose,
Qh＝Qi1-Qi2
d. a frostingEnergy efficiency ratio COP of air source heat pump system in defrosting periodsIn order to realize the purpose,
Figure RE-FDA0002399608300000061
the compressor, the water source pump and the circulating pump in the water source heat pump system are main power consumption equipment;
under different rotating speeds n of the motor, the relation between the power P of the load, the torque T and the rotating speed n is Tn/9550, and when the rotating speed n is 1, the consumed power is P1; when the rotating speed is n2, the consumed power is P2; if n1 is the rated speed, P1 is the rated power consumed;
the torque T of the water source pump load is in direct proportion to the square of the rotating speed n, namely T is KTn2, the relational expression of the power P of the load and the rotating speed n is P Tn/9550 KPn, KP is the power constant of the quadratic load, the power consumed by the water pump is in direct proportion to the rotating speed cube, when the water pump is controlled by a frequency converter to operate, the output frequency of the frequency converter is f1, the rotating speed of the water pump is n1, the flow rate is Q1, and the shaft power of a water pump motor is P1; the frequency converter has the output frequency of f2, the water pump rotating speed of n2, the flow rate of Q2, the shaft power of the water pump motor of P2, and Q1:Q2＝n1:n2，Q1:Q2＝n1:n2I.e. the power consumed by the motor is proportional to the 3 rd power of its rotational speed;
the power consumption of the ground source heat pump is mainly consumed by a water source heat pump unit, a submersible pump, a well water circulating pump, an air conditioner circulating pump and a tail end fan coil;
s32, calculating the loss of the ice storage air conditioning point, including the control of the ice storage temperature and the air supply temperature;
s33, calculating the electric loss of the electric heating boiler, wherein the electric loss of the electric heating boiler comprises the electric loss in the controller and the electric loss in the water pump; the efficiency of the electric boiler is
Figure RE-FDA0002399608300000071
wherein η is the efficiency of the electric boiler, eUser' sIs the electrical energy output to the user; w is input electric energy
S34, calculating the electrical loss of the water pump, wherein the electrical loss of the water pump mainly comprises the electrical losses of a boiler feed pump, a circulating water pump, a condensate lift pump, a drain pump, a mortar pump and a speed regulating oil pump, the water pump is reasonably configured, and the running speed of the water pump is properly adjusted to meet the requirement of load change.
8. The method according to claim 1
Figure RE-FDA0002399608300000072
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: calculating the power consumption of the energy storage system, namely calculating the charge and discharge loss of the distributed battery energy storage system,
for the charging situation, the charging efficiency of the ith distributed battery energy storage system is set as follows:
ηi,cha＝αi,cha-βi,cha·Pi,cha
wherein alpha isi,chaand betai,chaIs a charge constant; pi,chaFor charging power, Pi,cha>0 represents BESS input power [. eta. ]i,chaTo the charging efficiency;
internal power P of the distributed battery energy storage system during chargingi,bat,cha＝Pi,cha·ηi,cha. Setting the electricity price of a power grid as rho and the period as delta T, and setting the charging loss cost P of the distributed battery energy storage system per periodi,cha,lossIs defined as:
Pi,cha,loss＝ρ·Pi,cha·(1-ηi,cha)·ΔT
for the discharging condition, the discharging efficiency of the distributed battery energy storage system is set as follows:
ηi,dch＝αi,dch-βi,dch·Pi,dch
wherein alpha isi,dchand betai,dchIs the discharge constant; pi,dchFor discharge power, Pi,dch>0 represents BESS output power [. eta. ]i,dchThe discharge efficiency is obtained.
Internal power P of distributed battery energy storage system during dischargingi,bat,dch＝Pi,dch/ηi,dchDischarge loss cost per cycle Ci,dch,lossCan be defined as:
Figure RE-FDA0002399608300000073
9. the method according to claim 1
Figure RE-FDA0002399608300000074
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: the electricity of the alternating current-direct current hybrid distributed system
Figure RE-FDA0002399608300000075
The efficiency is a comprehensive energy efficiency evaluation index of the alternating current-direct current hybrid distributed system, and the calculation formula is as follows,
Figure RE-FDA0002399608300000081
wherein eta isAC/DC，EIs system electricity
Figure RE-FDA0002399608300000082
Efficiency, PDThe electric quantity, P, delivered to the large gridsFor the total amount of thermal radiation received by the photovoltaic cell, PgTotal heat value of natural gas, P, for distributed combustion of natural gasBTotal heat value of hydrogen for fuel cell combustionAC/DC power supplyFor electricity of AC-DC power supply system
Figure RE-FDA0002399608300000083
Loss, piDistributed power generationElectricity for distributed generation systems
Figure RE-FDA0002399608300000084
Loss, piElectricity storageFor electricity of electricity storage systems
Figure RE-FDA0002399608300000085
Loss;
the AC/DC power supply system
Figure RE-FDA0002399608300000086
The efficiency is calculated by the formula
Figure RE-FDA0002399608300000087
Wherein the content of the first and second substances,
Figure RE-FDA0002399608300000088
for electricity of AC-DC power supply system
Figure RE-FDA0002399608300000089
Efficiency, PJZFor the input power of the alternating current and direct current power supply system,
Figure RE-FDA00023996083000000810
respectively distribution line loss, power electronic transformer loss and rectifier loss, t in an AC/DC power supply system0、t1Starting and ending time of the current flowing for the AC/DC power supply system;
the distributed power generation system electricity
Figure RE-FDA00023996083000000811
The efficiency is calculated by the formula
Figure RE-FDA00023996083000000812
Wherein the content of the first and second substances,
Figure RE-FDA00023996083000000813
electricity for distributed generation systems
Figure RE-FDA00023996083000000814
Efficiency;
ΠCCHP＝Pg·Hs-Egasout
therein, IICCHPElectricity for natural gas distributed generation
Figure RE-FDA00023996083000000815
Loss, HsFor high calorific value of natural gas, EgasoutGenerating capacity for natural gas distributed power generation;
ΠTur-Gen＝m·h1-Eout
therein, IITur-GenFor electricity of turbines and generators
Figure RE-FDA00023996083000000816
Loss, m is the mass of steam fed to the turbine, h1To the enthalpy of the steam input to the turbine, EoutElectric energy output by the generator;
Figure RE-FDA00023996083000000817
wherein the content of the first and second substances,
Figure RE-FDA00023996083000000818
loss of the photovoltaic distributed power generation system;
Figure RE-FDA00023996083000000819
wherein the content of the first and second substances,
Figure RE-FDA00023996083000000820
for the depletion of the solar module, SpaAmount of heat radiation received for solar module, PoutIs the sunThe electrical energy output power of the energy component;
Figure RE-FDA0002399608300000091
wherein the content of the first and second substances,
Figure RE-FDA0002399608300000092
in order to be a loss of the photovoltaic inverter,
Figure RE-FDA0002399608300000093
is the power loss of the inverter;
Figure RE-FDA0002399608300000094
Figure RE-FDA0002399608300000095
wherein, Δ PTFor active power loss, Δ QTFor reactive power loss, Δ P0、ΔQ0For no-load active and reactive power losses, Δ PS、ΔQSFor loading active power, reactive power, ScaFor real load power, SN.TRated capacity for the transformer;
the electricity storage system is electrically powered
Figure RE-FDA00023996083000000920
The efficiency is calculated by the formula
Figure RE-FDA0002399608300000096
Figure RE-FDA0002399608300000097
Figure RE-FDA0002399608300000098
Wherein the content of the first and second substances,
Figure RE-FDA0002399608300000099
for electricity of electricity storage systems
Figure RE-FDA00023996083000000910
Efficiency, PHThe total heating value of the hydrogen gas combusted for the fuel cell,
Figure RE-FDA00023996083000000911
in order to store the energy of the battery for the loss,
Figure RE-FDA00023996083000000912
is the depletion of the hydrogen fuel cell, eUser' sIs the electrical energy output to the user.
10. The method according to claim 9
Figure RE-FDA00023996083000000913
The method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system is characterized by comprising the following steps of: the loss of a distribution line, the loss of a power electronic transformer and the loss of a rectifier in the AC/DC power supply system are respectively calculated by the following formulas,
Figure RE-FDA00023996083000000914
wherein the content of the first and second substances,
Figure RE-FDA00023996083000000915
for loss of distribution line, Δ PLIn order to achieve a loss of line power,
Figure RE-FDA00023996083000000916
wherein, Δ PLIn order to achieve a loss of line power,λ is a power factor, U is a line operating voltage, I is a current flowing through the circuit, R is a line resistance, ρ is a line resistivity, l is a line length, and a is a line sectional area;
Figure RE-FDA00023996083000000917
wherein the content of the first and second substances,
Figure RE-FDA00023996083000000918
in order to be a loss of the power electronic transformer,
Figure RE-FDA00023996083000000919
power loss of each part of the power electronic transformer is achieved;
Figure RE-FDA0002399608300000101
wherein, PjnFor winding losses, Rn(1),Rn(2) Is the resistance of the primary and secondary windings under the nth harmonic,
Figure RE-FDA0002399608300000102
is the effective value of the harmonic current flowing through the primary winding and the secondary winding;
Figure RE-FDA0002399608300000103
Figure RE-FDA0002399608300000104
wherein, PHnFor hysteresis loss, PEFor eddy current losses, n is the harmonic order, UnIs an nth harmonic voltage, U1Is a fundamental voltage phinIs the initial phase angle of n-th harmonic voltage, s is the core material coefficient, BriIs the radial magnetic induction in the ith cell, BziIs the axial magnetic induction, omega, in the ith cellAt angular frequency, ρ is the resistivity of the material, b, d are the wire dimensions, RiIs the distance from the center of gravity of the ith unit to the center line of the core, ViThe volume occupied by the conductor in the ith unit;
Figure RE-FDA0002399608300000105
wherein the content of the first and second substances,
Figure RE-FDA0002399608300000106
for losses of rectifiers, Pss、PSWPower loss for the power switch IGBT;
Figure RE-FDA0002399608300000107
PSW＝fPWM×(ESW(on)+ESW(off))
wherein, Pss、PSWFor power loss of the power switch IGBT, ICPIs the peak value of the sinusoidal output current, VCE(sat)Is the peak current ICPAnd D is the duty ratio, and theta is the power factor angle.
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