CN111178657B - exergy -based AC/DC hybrid distributed system electric loss and energy efficiency evaluation method - Google Patents

Abstract

The invention discloses a method based onThe method for evaluating the electric loss and the energy efficiency of the AC/DC hybrid distributed system comprises an AC/DC 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 AC/DC 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 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 systemEfficiency and finally obtain electricity of the AC/DC hybrid distributed systemEfficiency is improved. The advantages are that: by calculating various electric losses and heat losses in the system, the comprehensive energy loss rate in the system is obtained so as toAs a parameter for evaluating the loss of the system, an index system is established, and the energy utilization efficiency of the system is quantitatively analyzed.

Description

exergy -based AC/DC hybrid distributed system electric loss and energy efficiency evaluation method

Technical Field

The invention relates to the field of distributed system energy conservation in an electric power system, in particular to a power-saving system based on a distributed system The method for evaluating the electric loss and the energy efficiency of the AC/DC hybrid distributed system.

Background

Distributed systems have been rapidly developed in recent years, and the demonstration of distributed systems using multiple types of energy as main features has received a great deal of attention. However, unlike large power grids, distributed systems have short transmission distances and a large number of energy forms in the system, including not only electric energy transmission, but also production, transmission and use of heat energy, and in particular, an ac-dc hybrid distributed system, the electric energy loss calculation is complex in both ac and dc transmission paths. Therefore, it is very difficult to perform power loss calculation and energy efficiency evaluation for the distributed system.

At present, students at home and abroad do a certain research on energy efficiency, take electricity users in a fixed area as evaluation targets and analyze the energy utilization efficiency of the users, but the quantitative analysis usually aims at single aspect and single index quantification, and cannot consider the energy efficiency evaluation of all equipment types and all energy utilization scenes in the energy utilization area. In particular, energy efficiency analysis performed on a distributed system is often performed on a pure alternating current distributed system, but no analysis is performed on an alternating current-direct current hybrid distributed system.

Disclosure of Invention

The invention aims to provide a device based on the following componentsThe method for evaluating the electric loss and the energy efficiency of the alternating current-direct current hybrid distributed system solves the problems in the prior art.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

based onThe method for evaluating the electric loss and the energy efficiency of the AC/DC hybrid distributed system comprises an AC/DC power supply system, a distributed energy supply system, a thermodynamic system and an energy storage system; comprises the following steps of the method,

s1, calculating the electrical loss of the AC/DC power supply system;

s2, calculating the electrical loss of the distributed energy supply system;

s3, calculating the electrical loss of the thermodynamic system;

s4, calculating the electrical loss of the energy storage system;

s5, respectively acquiring the electricity of the AC/DC power supply system, the distributed functional system, the thermodynamic system and the energy storage system according to the electricity loss of the AC/DC power supply system, the distributed functional system, the thermodynamic system and the energy storage systemEfficiency and finally obtain the electricity of the AC/DC hybrid distributed system>Efficiency is improved.

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 rectifier loss;

s14, acquiring the electric loss of the alternating current-direct current power supply system according to the line loss, the power electronic transformer loss and the rectifier loss.

Preferably, the step S11 includes the following specific contents,

s111, calculating statistical line loss; the statistical line loss is the difference between the power supply quantity and the electricity sales quantity, and the calculation formula is that the statistical line loss is = [ (power supply quantity-electricity sales quantity)/power supply quantity ] ×100%;

s112, calculating theoretical line loss; the theoretical line loss is obtained by theoretical calculation according to the parameters of the power supply equipment, the current running mode and the current distribution of the power grid and the load condition;

s113, calculating and managing line loss; the management line loss is the loss electric quantity generated by the factors in the management aspect, and the calculation formula is that the management line loss=statistical line loss (actual line loss) -theoretical line loss;

s114, calculating economic line loss; the theoretical line loss of the line with fixed equipment conditions changes along with the change of the electric load, and the line has the lowest line loss rate, namely 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 the upper level through measurement and calculation according to the actual line loss of the power grid and combining the power grid structure, the load trend 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 AC/DC power supply system.

Preferably, step S12 includes the following specific details,

s121, calculating hysteresis loss of the power electronic transformer; the hysteresis loss frequency is proportional to the quadratic of the hysteresis coefficient of maximum magnetic flux density, and the losses due to hysteresis under harmonic conditions can be expressed as,

wherein P is _Hn Is hysteresis loss, n is harmonic frequency, U _n Is the n-order harmonic voltage (V), U ₁ Is the fundamental voltage (V), phi _n The primary phase angle (degree) of the voltage of the n-order harmonic wave is s which is the material coefficient of the iron core;

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,

wherein B is _ri For the i-th in-cell radial magnetic induction (T), B _zi Is the axial magnetic induction intensity (T) in the ith unit, omega is angular frequency (Hz), rho is material resistivity (omega-m), b, d is wire size, R _i For the centre of gravity of the ith unit to the core centre lineDistance (mm), V _i Volume (mm 3) occupied by the conductor in the ith cell;

s123, calculating 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 the secondary winding coil of the transformer is called basic copper loss, the effective resistance of the lead can be increased to generate additional copper loss due to skin effect and proximity effect caused by a leakage magnetic field, the additional copper loss also comprises eddy current loss generated by an oil tank wall and a metal structural member and internal circulation loss generated by parallel winding of the lead, under the direct current magnetic bias effect, the winding loss is calculated by the formula,

wherein P is _jn Is the winding loss (W), R _n (1)、R _n (2) The resistance (omega) of the primary and secondary windings at the n-th harmonic,an effective value (I) for harmonic currents flowing through the primary and secondary windings;

and S124, adding the hysteresis loss, the eddy current loss and the winding loss to obtain the power electronic transformer loss.

Preferably, the rectifier is controlled by PWM, and the step S13 includes the following specific matters,

s131, calculating average conduction loss; when the rectifier is on and conducting current, the product of the on saturation voltage and the on current forms a conduction loss, which must be multiplied by the duty cycle factor to find the average loss, which is the average conduction loss of the rectifier as follows,

Wherein P is _SS To average conduction loss, I _CP Peak value of sinusoidal output current; v (V) _CE(sat) For peak current I _CP Saturation voltage of lower IGBTLowering; d is the duty cycle; θ is the power factor angle;

s132, calculating average switching loss; the switching loss is the power loss during the transition of the tube on and off, the average switching loss is obtained by multiplying the unit pulse total switching energy by the PWM frequency,

P _SW ＝f _PWM ×(E _SW(on) +E _SW(off) )

wherein P is _SW To average the switching loss, f _PWM For PWM frequency, E _SW(on) And E is _SW(off) The energy of the unit pulse master switch when being opened and closed respectively.

Preferably, the distributed energy supply system comprises a combined cooling heating and power system and photovoltaic distributed equipment; the step S2 includes the following specific matters,

s21, reflecting the electricity consumption of the combined cooling heating and power system through the electricity efficiency and the energy cascade utilization; respectively calculating equivalent electrical efficiency, reduced electrical efficiency, energy cascade utilization rate and energy saving rate of the combined cooling heating power system;

the equivalent electrical efficiency is the ratio of the primary energy consumption of the combined cooling, heating and power system, the equivalent electrical efficiency is the electrical quantity consumed by respectively converting the cooling energy or the heat energy in the combined cooling, heating and power system into the corresponding conventional system to output the same cooling energy or heat energy, the equivalent electrical efficiency is calculated as follows,

Wherein eta ₁ For equivalent electrical efficiency, COP _h The heat supply coefficient of the electric heat pump;

the reduced power generation rate is the power generation efficiency calculated by assuming that the energy consumption of the cold and heat output of the combined cooling, heating and power system is the same as that of the reference conventional power generation, the calculation formula is,

wherein eta ₂ To fold the electric effectA rate;

the energy cascade utilization rate comprehensively considers the performance of the cold-hot electric products from the angles of energy taste and cascade utilization, expresses the inequality of different products by using the uniformly quantized energy level taste coefficients as the weight coefficients of the cold, hot and electric, considers the quantity and grade of consumed energy and changes along with the change of comparison conditions, and has the calculation formula of,

wherein eta ₃ The energy cascade utilization rate is used; a is that _e The energy level taste coefficient of electricity; a is that _h Is the thermal energy level taste coefficient; a is that _c Is the thermal energy level taste coefficient; a is that _f Is the energy level taste coefficient of the fuel; ΔE is the energy transfer processA change; Δh is the change in enthalpy of the energy transfer process;

the energy saving rate is a thermal economy analysis method based on a first law of thermodynamics, and the energy saving condition of the combined cooling, heating and power system is evaluated by adopting a combined cooling, heating and power mode relative to the primary energy saving rate of the combined cooling, heating and power system under the condition of supplying the same heat, cold and electric quantity in a heating period or a cooling period; the energy saving rate calculation type of the heating period and the cooling period are respectively as follows,

Wherein eta _zh The energy saving rate is used for the heating period; η (eta) _zc For coolingEnergy saving rate; η (eta) _e The power supply efficiency for the combined supply; η (eta) _h The heat supply efficiency for the combined supply; η (eta) _b The heat supply efficiency of the boiler is improved; COP of _a Is the refrigeration coefficient of the absorption refrigerator; COP of _e Is the refrigeration coefficient of the electric refrigerator;

s22, calculating the loss of an electrical part of the photovoltaic distributed equipment, wherein the loss comprises the reactive loss of a transformer and the effect of the whole efficiency of an inverter;

the reactive power loss of the transformer comprises no-load reactive power loss and load reactive power loss, the calculation formula is as follows,

Q _T ＝Q _O.T +Q _P.T

wherein Q is _T For reactive power loss of transformer, Q _O.T For no-load reactive power loss, Q _P.T U for reactive load loss _d % is the transformer short circuit voltage percentage; i _OT % is the percentage of the no-load current of the transformer; s is S _N.T Rated capacity of the transformer; s is S _T Is the actual load of the transformer; p (P) _PV Is the photovoltaic power transmitted through the transformer;

the efficiency of the inverter directly influences the effective power generation amount and the power generation cost of the photovoltaic power generation system, so that the inverter has the tracking control management function of the maximum power point and changes 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 air source heat pump system electric losses and water source heat pump system electric losses;

The air source heat pump system provides positive heat supply to the indoor in the heating stage and positive heat extraction from the indoor in the defrosting stage according to the electricity consumption condition in a complete heating (frosting)/defrosting (regenerating) period, and lists an energy conservation equation of the air source heat pump system,

a. in the heating (frosting) process, the energy conservation equation is that,

Q _i1 ＝W ₁ +Q _o1

Q _o1 ＝Q _o1,s +Q _o1,l

wherein Q is _o1,s For sensible heat quantity in frosting process, Q _o1,l Is the latent heat of the frosting process;

b. the defrosting (regenerating) process, the air source heat pump system can possibly take heat from the user side and possibly take heat from other channels, so as to provide the heat required by the defrosting (regenerating) process, and the energy conservation equation is that,

Q _o2 ＝W ₂ +Q _i2

Q _o2 ＝Q _o2,s +Q _o2,l

wherein Q is _o2,s For sensible heat quantity in frosting process, Q _o2,l Is the latent heat of the frosting process;

c. actual heating quantity Q of air source heat pump system to user in one heating/defrosting period _h In order to achieve this, the first and second,

Q _h ＝Q _i1 -Q _i2

d. energy efficiency ratio COP of air source heat pump system in one frosting/defrosting cycle _s In order to achieve this, the first and second,

the compressor, the water source pump and the circulating pump in the water source heat pump system are main power consumption equipment;

the relation between the power P of the load, the torque T and the rotating speed n of the compressor is P=Tn/9550 under different rotating speeds n of the motor, and when the rotating speed is n1, the consumed power is P1; when the rotating speed is n2, the consumed power is P2; then P1/p2=n1/n 2, when n1 is the rated rotational speed, P1 is the rated power consumed;

The torque T of the water source pump is directly proportional to the square of the rotating speed n, namely TThe relation between the power P of the load and the rotation speed n is p=tn/9550=kpn, KP is the power constant of the quadratic load, the power consumed by the water pump is proportional to the cube of the rotation speed, when the water pump is controlled to operate by the frequency converter, the output frequency of the frequency converter is f1, the rotation speed of the water pump is n1, the flow is Q1, and the shaft power of the water pump motor is P1; the output frequency of the frequency converter is f2, the rotation speed of the water pump is n2, the flow rate is Q2, the shaft power of the water pump motor is P2, then Q ₁ :Q ₂ ＝n ₁ :n ₂ ， Q ₁ :Q ₂ ＝n ₁ :n ₂ I.e. the power consumed by the motor is proportional to the 3 rd power of its rotation speed;

the electricity 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 ice storage air conditioner point loss, including the control of ice storage temperature and air supply temperature;

s33, calculating electric loss of the electric heating boiler, wherein the electric loss of the electric heating boiler comprises electric loss in a controller and electric loss in a water pump; the efficiency of the electric heating boiler is

Wherein eta is the efficiency of the electric heating boiler; e, e _{User' s} For outputting electric energy to a user; w is the input electric energy

S34, calculating the electric loss of the water pump, wherein the electric loss of the water pump mainly comprises the electric loss of a boiler water supply pump, a circulating water pump, a condensate pump, a drainage pump, a mortar pump and a speed regulating oil pump, and the water pump is reasonably configured, and the running speed of the water pump is properly regulated so as to adapt to the requirement of load change.

Preferably, calculating the electrical 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 follows:

η _i,cha ＝α _i,cha -β _i,cha ·P _i,cha

wherein alpha is _i,cha And beta _i,cha Is a charge constant; p (P) _i,cha To charge power, P _i,cha >0 represents the BESS input power; η (eta) _i,cha Is the charging efficiency;

then the internal power P of the distributed battery energy storage system during charging _i,bat,cha ＝P _i,cha ·η _i,cha . Let the power grid electricity price be ρ, the period be DeltaT, and the charge loss cost per period P of the distributed battery energy storage system _i,cha,loss The definition is as follows:

P _i,cha,loss ＝ρ·P _i,cha ·(1-η _i,cha )·ΔT

for the discharging condition, the discharging efficiency of the distributed battery energy storage system is set as follows:

η _i,dch ＝α _i,dch -β _i,dch ·P _i,dch

wherein alpha is _i,dch And beta _i,dch Is a discharge constant; p (P) _i,dch For discharging power, P _i,dch >0 represents the BESS output power; η (eta) _i,dch Is the discharge efficiency.

Internal power P of the distributed battery energy storage system upon discharge _i,bat,dch ＝P _i,dch /η _i,dch Cost of discharge loss per cycle C _i,dch,loss Can be defined as:

preferably, the electricity of the AC/DC hybrid distributed systemThe efficiency is the comprehensive energy efficiency evaluation index of the alternating current-direct current hybrid distributed system, the calculation formula is as follows,

wherein eta _AC/DC，E To power the systemEfficiency, P _D For conveying electric quantity of large power grid, P _s For the total amount of thermal radiation received by the photovoltaic cell, P _g Total heating value of natural gas P for distributed combustion of natural gas _B Pi, total heat value of hydrogen burnt by fuel cell _{Ac/dc power supply} For the power of AC/DC power supply system>Loss of pi _{Distributed power generation} Electric +.>Loss of pi _{Power storage} For electricity of electricity storage system>Loss;

the AC/DC power supply system is powered onThe calculation formula of the efficiency is that

Wherein eta _EAD For supplying power to ac-dc power supply systemsEfficiency, P _JZ Is the input power of the AC/DC power supply system,respectively, power distribution line loss, power electronic transformer loss and rectifier loss in an AC/DC power supply system, t ₀ 、t ₁ The start and end time of the alternating current/direct current power supply system;

the distributed power generation system is electricThe calculation formula of the efficiency is that

Wherein,electric +.>Efficiency is improved;

Π _CCHP ＝P _g ·H _s -E _gasout

wherein pi (n) _CCHP Electricity for distributed generation of natural gasLoss of H _s Is the high-order heating value of natural gas, E _gasout Generating energy for the distributed generation of natural gas;

Π _Tur-Gen ＝m·h ₁ -E _out

wherein, pi _Tur-Gen For steam turbines and generatorsLoss, m is the mass of steam fed into the turbine, h ₁ For inputting the enthalpy value of the steam of the turbine, E _out The electric energy is output by the generator;

wherein,losses for a photovoltaic distributed power generation system;

wherein,s is the loss of the solar component _pa For receiving thermal radiation from solar modules Amount, P _out The power output is the electric energy of the solar energy component;

wherein,for losses of the photovoltaic inverter, +.>Is the power loss of the inverter;

wherein DeltaP _T Delta Q is the active power loss _T For reactive power loss, ΔP ₀ 、ΔQ ₀ As no-load active and reactive power loss, deltaP _S 、ΔQ _S Is the active power and the reactive power of the load, S _ca Is the actual power, S _N.T Rated capacity of the transformer;

the electric power storage systemThe calculation formula of the efficiency is that

Wherein,for electricity of electricity storage system>Efficiency, P _H Total heating value of hydrogen for fuel cell combustion, +.>For energy storage battery loss, < >>E is the loss of the hydrogen fuel cell _{User' s} For the output of electrical energy to the user.

Preferably, the distribution line loss, the power electronic transformer loss and the rectifier loss in the ac/dc power supply system are respectively calculated by the following formulas,

wherein,ΔP, the loss of distribution lines _L In order to achieve a line power loss,

wherein DeltaP _L The power loss of the circuit, lambda is a power factor, U is a circuit running voltage, I is a current flowing through the circuit, R is a circuit resistance, rho is a circuit resistivity, l is a circuit length, and A is a circuit sectional area;

wherein,for losses of the power electronic transformer, +.>P _Hn 、P _E Power loss for each part of the power electronic transformer;

Wherein P is _jn R is the winding loss _n (1),R _n (2) The resistances of the primary and secondary windings at the n-th harmonic,is the effective value of the harmonic current flowing through the primary and secondary windings;

wherein P is _Hn For hysteresis loss, P _E Is eddy current loss, n is harmonic frequency, U _n Is the n-order harmonic voltage, U ₁ Is the fundamental voltage phi _n Is the initial phase angle of the n-order harmonic voltage, s is the material coefficient of the iron core, B _ri For the i-th intra-cell radial magnetic induction intensity, B _zi Is the axial magnetic induction intensity in the ith unit, omega is angular frequency, rho is material resistivity, b, d is wire size, R _i V is the distance from the center of gravity of the ith unit to the center line of the iron core _i The volume occupied by the conductor in the ith unit;

wherein,p, the loss of rectifier _ss 、P _SW Power loss for the power switch IGBT;

P _SW ＝f _PWM ×(E _SW(on) +E _SW(off) )

wherein P is _ss 、P _SW For power loss of power switch IGBT, I _CP Peak value of sinusoidal output current, V _CE(sat) For peak current I _CP The saturation voltage drop of the lower IGBT, D is the duty cycle, and θ is the power factor angle.

The beneficial effects of the invention are as follows: 1. the invention improves the accuracy and efficiency of electric loss and energy consumption evaluation in the AC/DC hybrid distributed system; by calculating various electric losses and heat losses in the distributed system, the comprehensive energy loss rate in the distributed system is obtained As a parameter for evaluating the loss of the distributed system, an evaluation method is established, and the energy utilization efficiency of the distributed system is quantitatively analyzed. 2. The evaluation system is used for analyzing the AC/DC hybrid distributed system, so that the accuracy and reliability of energy utilization rate calculation of the distributed system can be effectively improved, and the evaluation method can play a full guiding role in the construction and operation processes of the distributed system, improve the benefits of the distributed system and reduce the energy waste condition in the distributed system.

Drawings

FIG. 1 is a flow chart of an evaluation method according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the detailed description is presented by way of example only and is not intended to limit the invention.

As shown in fig. 1, in the present embodiment, there is provided a base stationAc/dc of (a)The method comprises the steps of evaluating the electric loss and the energy efficiency of a hybrid distributed system, wherein the AC/DC distributed system comprises an AC/DC power supply system, a distributed energy supply system, a thermodynamic system and an energy storage system; comprises the following steps of the method,

S1, calculating the electrical loss of the AC/DC power supply system;

s2, calculating the electrical loss of the distributed energy supply system;

s3, calculating the electrical loss of the thermodynamic system;

s4, calculating the electrical loss of the energy storage system;

s5, respectively acquiring the electricity of the AC/DC power supply system, the distributed functional system, the thermodynamic system and the energy storage system according to the electricity loss of the AC/DC power supply system, the distributed functional system, the thermodynamic system and the energy storage systemEfficiency and finally obtain the electricity of the AC/DC hybrid distributed system>Efficiency is improved.

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 rectifier loss;

s14, acquiring the electric loss of the alternating current-direct current power supply system according to the line loss, the power electronic transformer loss and the rectifier loss.

In this embodiment, the step S11 includes the following specific details,

the reasons for the line loss generated in the transmission process of the electric energy include:

the wire of the line is mostly a conductor of copper or aluminum material due to the resistance. When a current is passed, it presents a resistance to the current, which is referred to as the resistance of the conductor. In the transmission of electric energy in an electric power network, the resistance of the conductor must be overcome, so that electric energy loss occurs, which is seen in the heat generation 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;

Because of the reason of management, the management of the power supply and utilization management department and related personnel is not strict enough, loopholes appear, and the power loss caused by the actions of illegal power utilization and electricity stealing of users, power grid element electricity leakage, error of an electric energy metering device, meter reading personnel missing, wrong reading and the like is caused. The loss is not clear because of no regular rule and difficult measurement and calculation. 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 statistical line loss; the statistical line loss is calculated according to an electric energy meter index, the statistical line loss is the difference between the power supply quantity and the sales quantity, and the calculation formula is that the statistical line loss is = [ (power supply quantity-sales quantity)/power supply quantity ] ×100%;

s112, calculating theoretical line loss; the theoretical line loss is obtained by theoretical calculation according to the parameters of the power supply equipment, the current running mode and the current distribution of the power grid and the load condition;

s113, calculating and managing line loss; the management line loss is the loss electric quantity generated by the factors in the management aspect, and the calculation formula is that the management line loss=statistical line loss (actual line loss) -theoretical line loss;

s114, calculating economic line loss; the economic line loss is a line with fixed equipment condition, the theoretical line loss is not a fixed value, but varies along with the change of the power supply load, and the lowest line loss rate is actually existed, and is called economic line loss, and the corresponding current is called economic current;

S115, calculating rated line loss; the rated line loss is also called a line loss index, and is a line loss index approved by the upper level through measurement and calculation according to the actual line loss of the power grid and combining the power grid structure, the load trend 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 AC/DC power supply system.

In this embodiment, step S12 includes the following specific contents,

reasons for the point loss of power electronic transformers include:

the transformer, like the wire, is a conductor of copper or aluminum material for resistance. When a current is passed, 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 windings are 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 step up or step down. The process by which the current establishes a magnetic field in the electrical device, i.e. the electromagnetic conversion process. In this process, hysteresis and eddy currents are generated in the core of the electric device due to the alternating magnetic field, and the core heats up, thereby generating electric power loss. Since this loss is generated during electromagnetic conversion, it is called excitation loss, which causes the core to heat, and is also commonly called core loss.

The single capacity of the transformer is increased, the voltage level is increased, the internal structure of the large power transformer is more complex, and the electric energy loss problem is also more remarkable. The calculation of the power electronic transformer losses is classified into two types, harmonic and non-harmonic.

S121, calculating hysteresis loss of the power electronic transformer; the magnetization speed of the ferromagnetic substance in the magnetization process of the iron core material is behind the change speed of the external magnetic field, hysteresis is generated, and the process can bring about energy loss, namely hysteresis loss. The ferromagnetic material has a tendency to retain its magnetic properties, and when the ferromagnetic body is magnetized to a saturated state, the magnetic field strength will gradually decrease, and the magnetic induction strength B will decrease along a path slightly higher than the magnetic induction strength curve when the magnetic field strength is increased, and when the magnetic field strength decreases to zero, the magnetic induction strength is not equal to zero because the magnetic induction change in the magnetic body has a certain hysteresis relative to the magnetic field strength, i.e. the relationship between the magnetic field strength and the magnetic flux density is a closed curve showing 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 magnetic field, hysteresis loss equivalent to the area of a hysteresis loop is generated in each cycle of the iron core in unit area. This partial loss will be dissipated as heat energy into the surrounding medium, resulting in an increase in the temperature of the transformer and a decrease in efficiency.

The hysteresis loss frequency is proportional to the quadratic of the hysteresis coefficient of maximum magnetic flux density, and the losses due to hysteresis under harmonic conditions can be expressed as,

wherein P is _Hn Is hysteresis loss, n is harmonic frequency, U _n Is the n-order harmonic voltage (V), U ₁ Is the fundamental voltage (V), phi _n The primary phase angle (degree) of the voltage of the n-order harmonic wave is s which is the material coefficient of the iron core; the above equation shows that the magnitude of 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 factor, the higher the harmonic voltage, the greater the power factor.

S122, calculating the eddy current loss of the power electronic transformer; when alternating magnetic force lines pass through the conductor, induced electromotive force is generated in the conductor, and loop current is generated in the conductor under the action of the induced electromotive force to enable the conductor to generate heat, which is called eddy current. The loop current it produces is not output outwards as energy, but is lost in its own conductor, thus producing eddy current losses. The eddy current loss in the core is proportional to the square of the 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 non-uniform, with the field strength being lowest at the core center, increasing outwards from the center and highest at the edges, due to the anti-magnetization effect created by the eddy currents. Due to the influence of the law of electromagnetic induction, the change of the magnetic flux of the iron core will cause eddy currents to be generated in the iron 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,

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wherein B is _ri For the i-th in-cell radial magnetic induction (T), B _zi Is the axial magnetic induction intensity (T) in the ith unit, omega is angular frequency (Hz), rho is material resistivity (omega-m), b, d is wire size, R _i V is the distance (mm) from the center of gravity of the ith unit to the center line of the iron core _i Volume (mm 3) occupied by the conductor in the ith cell;

s123, calculating winding loss of the power electronic transformer; winding losses, also known as copper losses or variable losses, consist of basic copper losses and additional copper losses. The loss caused by the direct current resistance of the secondary winding coil 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 oil tank wall and the metal structural part, internal circulation 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 the secondary winding coil of the transformer is called basic copper loss, the effective resistance of the lead can be increased to generate additional copper loss due to skin effect and proximity effect caused by a leakage magnetic field, the additional copper loss also comprises eddy current loss generated by an oil tank wall and a metal structural member and internal circulation loss generated by parallel winding of the lead, under the direct current magnetic bias effect, the winding loss is calculated by the formula,

Wherein P is _jn Is the winding loss (W), R _n (1)、R _n (2) The resistance (omega) of the primary and secondary windings at the n-th harmonic,an effective value (I) for harmonic currents flowing through the primary and secondary windings;

and S124, adding the hysteresis loss, the eddy current loss and the winding loss to obtain the power electronic transformer loss.

In this embodiment, a three-phase voltage type PWM rectifier is widely used in industry, and this is taken as an example. For the most commonly used power switch IGBTs, the conduction and switching losses are the most dominant sources of losses in operation, said step S13 comprises the following details,

s131, calculating average conduction loss; when the IGBT is in on state and conducts current, the product of the on state saturation voltage and the on state current forms an on state loss. For an IGBT controlled by PWM, the on-loss must be multiplied by the duty cycle to find the average loss.

When the rectifier is in on state and conducts current, the product of on state saturation voltage and on state current forms conduction loss, which must be multiplied by duty cycle factor to find average loss, referring to the IGBT module manual, the steady state conduction loss of a single IGBT is as follows,

wherein P is _SS To average conduction loss, I _CP Peak value of sinusoidal output current; v (V) _CE(sat) For peak current I _CP Saturation voltage drop of the lower IGBT; d is the duty cycle; θ is the power factor angle; due to saturation voltage drop V of each IGBT module _CE(sat) All are different, so in order to reduce conduction loss, when selecting power module, V _CE(sat) Is a parameter of major concern.

S132, calculating average switching loss; the switching loss is the power loss during the transition process of switching on and switching off the tube, and I is measured in the transition process of switching according to the voltage and current waveform diagram in the switching process _C And V _C The waveform is multiplied point by point to obtain the instantaneous waveform of powerThe area below is the switching energy in joules/pulse.

The average switching loss is obtained by multiplying the PWM frequency by the total switching energy of the unit pulse,

P _SW ＝f _PWM ×(E _SW(on) +E _SW(off) )

wherein P is _SW To average the switching loss, f _PWM For PWM frequency, E _SW(on) And E is _SW(off) The energy of the unit pulse main switch when being opened and closed can be searched on the switching curve of the module manual according to the expected working current, and the calculated value can be used as a preliminary estimation.

In this embodiment, the distributed energy supply system includes a cogeneration system and a photovoltaic distributed device; the step S2 includes the following specific matters,

in a cogeneration system, if the prime mover produces more electrical energy than is required by the consumer, it can result in a loss of electrical energy. The steam turbine is also equipment with higher energy consumption in the combined cooling heating power system, and mainly the energy consumption of the steam turbine unit is mainly caused by the fact that the operation energy consumption of the steam turbine unit is increased due to the fact that the air cooling condenser is excessively high in vacuum, the temperature of cooling water in the unit is excessively high, and the actual operation load exceeds the specified parameters. The electricity consumption of the cogeneration system is reflected by the electrical efficiency and energy cascade utilization below.

S21, reflecting the electricity consumption of the combined cooling heating and power system through the electricity efficiency and the energy cascade utilization; respectively calculating equivalent electrical efficiency, reduced electrical efficiency, energy cascade utilization rate and energy saving rate of the combined cooling heating power system;

compared with the heat, the cold and the electric quantity, the electric quantity has the highest quality, but the heat, the cold and the electric quantity have the 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 heat quantity output by the corresponding conventional system, the equivalent electric efficiency is the ratio of the sum of the equivalent electric quantity and the primary energy consumption of the combined cooling, heating and power system, the equivalent electric quantity is the electric quantity consumed by respectively converting the cold quantity or the heat quantity in the combined cooling, heating and power system into the same cold quantity or the same heat quantity output by the corresponding conventional system, the equivalent electric efficiency is calculated as follows,

wherein eta ₁ For equivalent electrical efficiency, COP _h The heat supply coefficient of the electric heat pump; it can be seen that the weight of the cold and heat is related to the performance of the conventional system that produces a reference for cold and heat, the efficiency of the conventional system's electric heat pump and electric refrigerator has a great impact on the result of equivalent electrical efficiency. As technology advances, the efficiency of the electric heat pump and electric refrigerator of conventional systems will increase, the amount of cooling and heat will be more readily available, and the weighting factor for cooling and heat will be reduced.

The power generation efficiency is calculated when the energy consumption of the cold and heat output of the assumed system is the same as that of the reference separate-generation system. The heat supply efficiency of the separate production system adopts the heat supply efficiency of a boiler, the refrigeration efficiency adopts the refrigeration efficiency of an electric refrigerator, the calculation formula is,

wherein eta ₂ To reduce the electrical efficiency.

The energy cascade utilization rate comprehensively considers the performance of the cold and hot electric products from the angles of energy taste and cascade utilization, expresses the inequality of different products by taking the uniformly quantized energy level taste coefficient as the weight coefficient of cold, hot and electricity, considers the quantity and grade of consumed energy and changes along with the change of comparison conditions, and has the calculation formula of,

wherein eta ₃ The energy cascade utilization rate is used; a is that _e The energy level taste coefficient of electricity; a is that _h Is the thermal energy level taste coefficient; a is that _c Is the thermal energy level taste coefficient; a is that _f Is the energy level taste coefficient of the fuel; ΔE is the energy transfer processA change; Δh is the change in enthalpy of the energy transfer process; the energy cascade utilization rate comprehensively balances the essential difference of different energy conversion utilization processes from the energy consumption of the processes of power generation, refrigeration, heat supply and the like, the quality of products produced and the like, better distinguishes the quantity and quality of consumed energy, better distinguishes the inequality of cold and heat, and reflects the heat supply difference of different temperatures.

The energy saving rate is a thermal economy analysis method based on a first law of thermodynamics, and the energy saving condition of the combined cooling, heating and power supply system is evaluated by adopting a combined cooling, heating and power supply mode relative to the primary energy saving rate of the combined cooling, heating and power supply system (power grid power supply, boiler heat supply and electric refrigerator cold supply) under the condition of supplying the same heat, cold and electric quantity in a heat supply period or a cold supply period; the energy saving rate calculation type of the heating period and the cooling period are respectively as follows,

wherein eta _zh The energy saving rate is used for the heating period; η (eta) _zc The energy saving rate is used for the cold supply period; η (eta) _e The power supply efficiency for the combined supply; η (eta) _h The heat supply efficiency for the combined supply; η (eta) _b The heat supply efficiency of the boiler is improved; COP of _a Is the refrigeration coefficient of the absorption refrigerator; COP of _e Is the refrigeration coefficient of the electric refrigerator; it can be seen that the system parameters (eta _ce 、η _b 、COP _e ) Under certain conditions, the combined cooling heating and power system supplies heatThe energy saving rate in the period is improved along with the improvement of the power generation efficiency and the heat supply efficiency of the combined supply system, and the energy saving rate in the cold supply period is improved along with the improvement of the power generation efficiency, the heat supply efficiency and the refrigerating efficiency of the absorption refrigerator of the combined supply system. 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, and even the energy is not saved. The energy saving rate of the combined cooling heating power system has a great relation with the parameters of the separate power supply system, the obtained results have differences under different power grid power supply efficiency, boiler heat supply efficiency and electric refrigerator efficiency, and the energy saving rate is the same as the traditional heat efficiency, and the quality differences of cold, heat and electricity energy sources are not distinguished.

S22, calculating the loss of an electrical part of the photovoltaic distributed equipment, wherein the loss comprises the reactive loss of a transformer and the effect of the whole efficiency of an inverter;

as the capacity of the photovoltaic power station increases, reactive power loss inside the photovoltaic power station also gradually increases, thereby leading to an increase in active power loss inside the photovoltaic power station and on the transmission line. Reactive power requirements of grid-connected photovoltaic power stations mainly come from photovoltaic inverters, step-up transformers, transmission lines and grid-connected main transformers. The reactive loss of the transformer accounts for a main part during daytime power generation, and the charging power of the power transmission cable may account for a main part during night power outage. There are 2 kinds of transformers in a photovoltaic power station, 1 kind is a double split step-up transformer connected to a photovoltaic inverter, and the voltage class is usually 35kV. The other 1 is a step-up main transformer before grid connection of the photovoltaic power station, and the voltage class is the same as that of a power grid, and is usually 110kV.

The reactive power loss of the transformer comprises no-load reactive power loss and load reactive power loss, the calculation formula is as follows,

Q _T ＝Q _O.T +Q _P.T

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wherein Q is _T For reactive power loss of transformer, Q _O.T For no-load reactive losses, i.e. fixed losses, Q _P.T U for reactive load loss _d % is the transformer short circuit voltage percentage; i _OT % is the percentage of the no-load current of the transformer; s is S _N.T Rated capacity of the transformer; s is S _T Is the actual load of the transformer; p (P) _PV Is the photovoltaic power transmitted through the transformer; the photovoltaic power change will cause a drastic change in reactive power, i.e. a 1-fold change in photovoltaic power will cause a 2-fold change in reactive power. Because the solar energy changes greatly day and night, at night, the reactive power loss of the photovoltaic power station is quite different in day and night because the photovoltaic active output is 0 and the transformer is in an idle state.

For high power inverters, the operating efficiency must reach 90% or more than 95% at full load. Particularly at low load power, relatively high efficiency is still required. Meanwhile, the efficiency of the inverter directly influences the effective power generation amount and the power generation cost of the photovoltaic power generation system. In addition, in the design process of the inverter applied to the photovoltaic power generation system, the power loss of the inverter needs to be reduced to a certain extent, and the efficiency of the whole machine is effectively improved. The practical working efficiency of the general inverter of the 10kV level is only 70-80%, and when the general inverter is applied to a photovoltaic power generation system, the general inverter can cause 20-30% of the total power generation energy consumption. 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 the tracking control management function can be changed along with the corresponding change of the radiation capability of solar energy at any time. And the automatic on and off can be realized according to the difference of conditions such as sunrise, sunset and the like.

In this embodiment, the step S3 includes the following specific details,

s31, calculating heat pump electric losses, including air source heat pump system electric losses and water source heat pump system electric losses;

when the air source heat pump water heater is heated to a higher water temperature, the power consumption of the system is obviously increased, a large amount of air suction liquid is carried, the power consumption of the system is increased, the system performance (COP) is reduced, and the power consumption is increased. In order to determine the electricity consumption condition of the air source heat pump system in a complete heating (frosting)/defrosting (regenerating) cycle under the same heating quantity requirement, the same outdoor side and user side working conditions, a performance model of the air source heat pump system needs to be built.

Both the heating and defrosting (regeneration) processes of the heat pump system are non-steady state processes, so the overall performance should be described in terms of one heating/defrosting cycle. If the air source heat pump system is regulated to supply heat to the indoor in the heating stage, and to supply heat from the indoor in the defrosting stage, the energy conservation equation of the air source heat pump system is listed,

a. in the heating (frosting) process, the energy conservation equation is that,

Q _i1 ＝W ₁ +Q _o1

Q _o1 ＝Q _o1,s +Q _o1,l

wherein Q is _o1,s For sensible heat quantity in frosting process, Q _o1,l Is the latent heat of the frosting process;

b. the defrosting (regenerating) process, the air source heat pump system can possibly take heat from the user side and possibly take heat from other channels, so as to provide the heat required by the defrosting (regenerating) process, and the energy conservation equation is that,

Q _o2 ＝W ₂ +Q _i2

Q _o2 ＝Q _o2,s +Q _o2,l

Wherein Q is _o2,s For sensible heat quantity in frosting process, Q _o2,l Is the latent heat of the frosting process;

c. actual heating quantity Q of air source heat pump system to user in one heating/defrosting period _h In order to achieve this, the first and second,

Q _h ＝Q _i1 -Q _i2

d. energy efficiency ratio COP of air source heat pump system in one frosting/defrosting cycle _s In order to achieve this, the first and second,

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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 under different rotating speeds n of a dragging motor, the resistance torque T of the load is basically constant, namely T=constant, and the resistance torque T of the load is irrelevant to the rotating speed n. The relation between the power P of the load and the torque T, the rotational speed n is: p=tn/9550 when the rotation speed is n1, the consumed power is P1; when the rotation speed is n2, the consumed power is P2. Then: if n1 is the rated rotational speed, P1 is the rated power consumed when P1/p2=n1/n 2. That is, when the compression type circulating water unit controls the electric power machine to regulate speed by using the frequency converter, 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. The extent of this electrical loss is still considerable, as analyzed in theory.

The water pump belongs to the quadratic load. The resistive torque T of the load is proportional to the square of the rotational speed n, i.e., t= KTn2. Where KT is the torque constant of the quadratic load. The relation between the power P and the rotation speed n of the load is: p=tn/9550= KPn. Where KP is the power constant of the 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 rotation speed of the water pump is n1, the flow is Q1, and the shaft power of the water pump motor is P1; the output frequency of the frequency converter is f2, the rotation 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 ₁ :Q ₂ ＝ ₁ n: ₂ n， Q ₁ :Q ₂ ＝n ₁ :n ₂ I.e. the power consumed by the motor is proportional to the 3 rd power of its rotation speed; it can be seen that the power consumed by the motor is proportional to the 3 rd power of its rotational speed, and that a large amount of electrical energy is consumed when the rotational speed is increased. Therefore, when the water flow rate 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 the ground source heat pump system is mainly consumed by 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 the water pump systems is important in the ground water ground source heat pump system, the power consumption of the system is affected, the stable operation of the system is related sometimes, and the reasonable matching between the deep well pump and the circulating pump is particularly important.

S32, calculating the ice storage air conditioner point loss, including the control of ice storage temperature and air supply temperature;

when ice is stored in the ice storage air conditioning system, the temperature of the ice water outlet end of the refrigerator is generally required to be lower than minus 5 ℃, so that the evaporation temperature and the evaporation pressure of the refrigerator are reduced; on the other hand, because the cooling is carried out at night, the condensing temperature is lower than the daytime, the influence caused by the reduction of a bit of evaporating temperature can be compensated, in a word, the cooling capacity of the refrigerator can be reduced during cold accumulation, and the power consumption of unit cold quantity can be increased;

If the air supply temperature of the air conditioning system is high, the air supply amount under the same cooling load is increased, so that the power consumed by the operation of the fan is increased, the energy consumption of the system is larger, and the operation cost is increased. The power formula of the hydrodynamic fan can be deduced, and the power consumption of the fan can rise in a cubic way along with the increase of the air supply quantity. Further, an increase in the air supply volume means an increase in the size of the air supply duct, thereby increasing the initial investment in the system. Therefore, the increase of the air supply temperature can increase the power consumption of the ice storage air conditioning system.

S33, calculating electric loss of the electric heating boiler, wherein the electric loss of the electric heating boiler comprises electric loss in a controller and electric loss in a water pump; the efficiency of the electric heating boiler is

Wherein eta is the efficiency of the electric heating boiler; e, e _{User' s} For outputting electric energy to a user; w is the input electrical energy.

S34, calculating the electric loss of the water pump, wherein the electric loss of the water pump mainly comprises the electric loss of a boiler water supply pump, a circulating water pump, a condensate pump, a drainage pump, a mortar pump and a speed regulating oil pump, and the water pump is reasonably configured, and the running speed of the water pump is properly regulated so as to adapt to 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 a water pump accounts for about 40% of the power consumption of the plant. Among them, boiler feed water pump, circulating water pump, condensate pump, drain pump, mortar pump, speed-regulating oil pump, etc. are the most important. 1 30 ten thousand kW thermal generator sets, more than 80 pumps of various types are required to be configured, the installation power is about 1.8 ten thousand kW, the annual power consumption is about 1 hundred million kW.h, and the annual power consumption accounts for 4% -5% of the generated energy of the whole plant. Wherein 2 boiler feed pumps, 5 600kW of single machine, 3 circulating water pumps and 1100kW of single machine; and 2 condensing and lifting pumps, and 550kW are arranged on a single machine. The pumps have high installation power and long running time, and the power consumption accounts for more than 80% of the power consumption of the water pumps of the thermal power plant.

Unreasonable matching and large margin capacity; the water pump in the power plant is selected according to the maximum load of the boiler and the steam turbine. From the viewpoint of operation safety, the capacity of the auxiliary machine is generally selected to be larger than that of the main machine. If the capacity of the boiler water supply pump should be 1.1 times of the rated water supply capacity of the boiler, the capacity of the boiler must be larger than the output of the turbine, the turbine must be larger than the output of the generator, and the boiler water supply pump is stacked layer by layer, so that the design output of the fan water pump of the power plant is about 20% -30% larger than the actual operation requirement. Some influences of system resistance change, equipment abrasion, leakage, flow, pressure and the like on the margin are considered, so that the output of some power plant water pumps is more than 30% than that of the power plant water pumps actually needed, and the power consumption is greatly increased.

The constant-speed running 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, particularly, some generator sets which bear peak shaving operation have larger load change amplitude, and some of the load can be reduced from 100% load to 60% load or even lower. The fan and the water pump matched with the air conditioner are correspondingly adjusted to meet the requirements of a host. Because the water pump mostly adopts constant-speed operation, the load is inconvenient to adjust, and the opening of a valve is generally adjusted to control the flow and the pressure, so that great throttling loss is caused, and a great amount of electric energy is wasted.

The throttle operation is performed, and the electric energy waste is large; the high and medium pressure units produced in early stage of the thermal power plant in China generally adopt a main pipe to supply water, and a water pump runs at a constant speed and is regulated in a throttling way. When the water supply demand of the boiler is greatly changed, the water supply device is met by changing the running number of the water supply pumps and matching with valve adjustment; if the water supply amount demand change is small, the opening degree of the valve is changed to adjust. After 70 years of the 20 th century, in particular to large and medium thermal power generating units with the power of more than 100MW, unit system is generally adopted, namely 1 boiler is specially supplied by 1 or 2 water supply pumps, and constant-speed operation is still adopted. When the water pump runs at full load, 1 water feed pump can not meet the requirement; the 2 water supply pumps are adopted to supply water, the pressure and the flow are rich, and only throttling adjustment can be adopted to meet the requirement of load change, 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 water feeding pump valve reaches 8840 MW.h. According to the test of related departments, when the centrifugal water pump with the power of 1 piece of 40kW runs at 70% of rated flow, the power loss caused by throttling is about 15kW, which is equivalent to 30% -40% of the input power of a lost motor.

In this embodiment, the electrical loss of the energy storage system is calculated as the charge and discharge loss of the distributed Battery Energy Storage System (BESS),

for the charging situation, let the charging efficiency of the ith distributed battery energy storage system be:

η _i,cha ＝α _i,cha -β _i,cha ·P _i,cha

wherein alpha is _i,cha And beta _i,cha Is a charge constant; p (P) _i,cha To charge power, P _i,cha >0 represents the BESS input power; η (eta) _i,cha Is the charging efficiency;

then the internal power P of the distributed battery energy storage system during charging _i,bat,cha ＝P _i,cha ·η _i,cha Let the power grid electricity price be ρ, the period be DeltaT, and the charge loss cost per period P of the distributed battery energy storage system _i,cha,loss The definition is as follows:

P _i,cha,loss ＝ρ·P _i,cha ·(1-η _i,cha )·ΔT

for the discharging condition, the discharging efficiency of the distributed battery energy storage system is set as follows:

η _i,dch ＝α _i,dch -β _i,dch ·P _i,dch

wherein alpha is _i,dch And beta _i,dch Is a discharge constant; p (P) _i,dch For discharging power, P _i,dch >0 represents the BESS output power; η (eta) _i, dc _h Is the discharge efficiency.

Internal power P of the distributed battery energy storage system upon discharge _i,bat,dch ＝P _i,dch /η _i,dch Cost of discharge loss per cycle C _i,dch,loss Can be defined as:

summary of the ac/dc hybrid distributed system electrical/thermal loss distribution:

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an energy efficiency evaluation index system of an AC/DC hybrid distributed system:

and constructing an integrated energy efficiency evaluation index system oriented to the alternating current-direct current hybrid distributed system according to the four layers of the target layer, the system layer, the equipment layer and the element index layer.

In this embodiment, the ac/dc hybrid distributed system is powered The efficiency is the comprehensive energy efficiency evaluation index of the alternating current-direct current hybrid distributed system, the calculation formula is as follows,

wherein eta _AC/DC，E To power the systemEfficiency, P _D For conveying electric quantity of large power grid, P _s For the total amount of thermal radiation received by the photovoltaic cell, P _g Total heating value of natural gas P for distributed combustion of natural gas _B Is the total heat value of hydrogen burnt by the fuel cell, pi _{Ac/dc power supply} For the power of AC/DC power supply system>Loss of pi _{Distributed power generation} Electric +.>Loss of pi _{Power storage} For electricity of electricity storage system>Loss; electric->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 is powered onThe calculation formula of the efficiency is that

Wherein,for the power of AC/DC power supply system>Efficiency, P _JZ Is the input power of the AC/DC power supply system,respectively, the power distribution line loss and the power electronic transformation in the AC/DC power supply systemLoss of rectifier, t ₀ 、t ₁ And the start and end time of the alternating current/direct current power supply system is provided.

The power distribution line loss, the power electronic transformer loss and the rectifier loss in the AC/DC power supply system are respectively calculated by the following formulas.

Distribution circuit loss:

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Wherein,ΔP, the loss of distribution lines _L Is the line power loss.

Distribution line power loss:

wherein DeltaP _L The power loss of the circuit is represented by lambda, the power factor of the circuit, the running voltage of the circuit is represented by U, the current flowing through the circuit is represented by I, the circuit resistance is represented by R, the circuit resistivity is represented by rho, the length of the circuit is represented by l, and the sectional area of the circuit is represented by A.

Power electronics transformer losses:

wherein,for losses of the power electronic transformer, +.>P _Hn 、P _E Power losses are the parts of the power electronic transformer.

Winding power loss in a power electronic transformer in an alternating current-direct current hybrid distributed system:

wherein P is _jn R is the winding loss _n (1),R _n (2) The resistances of the primary and secondary windings at the n-th harmonic,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 AC/DC hybrid distributed system comprises two parts, namely hysteresis loss and eddy current loss. The power loss of the iron core is as follows:

wherein P is _Hn For hysteresis loss, P _E Is eddy current loss, n is harmonic frequency, U _n Is the n-order harmonic voltage, U ₁ Is the fundamental voltage phi _n Is the initial phase angle of the n-order harmonic voltage, s is the material coefficient of the iron core, B _ri For the i-th intra-cell radial magnetic induction intensity, B _zi Is the axial magnetic induction intensity in the ith unit, omega is angular frequency, rho is material resistivity, b, d is wire size, R _i V is the distance from the center of gravity of the ith unit to the center line of the iron core _i The volume occupied by the conductors in the ith cell.

Rectifier losses:

wherein,p, the loss of rectifier _ss 、P _SW Is the power loss of the power switch IGBT.

Power loss of power switch IGBT in rectifier in ac/dc hybrid distributed system:

P _SW ＝f _PWM ×(E _SW(on) +E _SW(off) )

wherein P is _ss 、P _SW For power loss of power switch IGBT, I _CP Peak value of sinusoidal output current, V _CE(sat) For peak current I _CP The saturation voltage drop of the lower IGBT, D is the duty cycle, and θ is the power factor angle.

The distributed power generation system is electricThe calculation formula of the efficiency is +.>

Wherein,electric +.>Efficiency is improved.

Π _CCHP ＝P _g ·H _s -E _gasout

Wherein, pi _CCHP Electricity for distributed generation of natural gasLoss of H _s Is the high-order heating value of natural gas, E _gasout The generated energy is generated by natural gas distributed generation.

Electricity from turbines and generators in natural gas distributed power generation systemsLoss, defined as:

∏ _Tur-Gen ＝m·h ₁ -E _out

wherein, pi _Tur-Gen For steam turbines and generatorsLoss, m is the mass of steam fed into the turbine, h ₁ For inputting the enthalpy value of the steam of the turbine, E _out Is the electric energy output by the generator.

Photovoltaic distributed power generationLoss:

wherein,is the loss of the photovoltaic distributed power generation system.

The power generation efficiency of the photovoltaic system is closely related to the photoelectric conversion efficiency of the photovoltaic power station component, namely the solar cell, so that the conversion efficiency of the single crystal solar cell is 17-22%, the polycrystalline baby is 16-19%, and the amorphous salicide is 6-10%. In addition, the output characteristic of the photovoltaic module can change along with the change of the radiation intensity and the temperature, when the air temperature is too high and the box radiation quantity is too high, the output current of the photovoltaic cell is larger than the short circuit current of the photovoltaic cell, and the equivalent resistance and the voltage drop of the photovoltaic cell are very large like a diode working under reverse voltage, so that the photovoltaic cell consumes power and generates heat, local high temperature can be caused after the time is long, hot spots are formed, the output performance of the photovoltaic module is seriously influenced, and the photoelectric conversion efficiency of the photovoltaic module in different geographic environments can also change. The loss of the solar module in the photovoltaic distributed power generation is as follows:

wherein,s is the loss of the solar component _pa P is the heat radiation amount received by the solar component _out Is the electrical output power of the solar module.

The power loss of the inverter in the photovoltaic distributed power generation mainly comprises the loss of other parts such as power electronic devices, direct-current side capacitance loss, filter loss and the like, and the loss of the photovoltaic inverter is defined as:

Wherein,for losses of the photovoltaic inverter, +.>Is the power loss of the inverter. The inverter is an indispensable component as a heart of a photovoltaic system, and power loss can also occur in the inverter due to electronic devices and inductance elements, and the power loss is ∈ ->Can be found by the data parameters given by the manufacturer.

Loss of a transformer for photovoltaic distributed power generation in a distributed power generation system is defined as:

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wherein DeltaP _T Delta Q is the active power loss _T For reactive power loss, ΔP ₀ 、ΔQ ₀ As no-load active and reactive power loss, deltaP _S 、ΔQ _S For loading active power, nonePower of work, S _ca Is the actual power, S _N.T Is the rated capacity of the transformer.

The electric power storage systemThe calculation formula of the efficiency is that

Wherein,for electricity of electricity storage system>Efficiency, P _H Total heating value of hydrogen for fuel cell combustion, +.>Is the loss of the energy storage battery. />E is the loss of the hydrogen fuel cell _{User' s} For the output of electrical energy to the user.

By adopting the technical scheme disclosed by the invention, the following beneficial effects are obtained:

the invention provides a method based onMethod and system for evaluating electric loss and energy efficiency of AC/DC hybrid distributed system, and obtaining comprehensive energy loss rate in the system by calculating various electric loss and heat loss in the system >As a parameter for evaluating the loss of the system, an index system is established, and the energy utilization efficiency of the system is quantitatively analyzed; the index system is utilized to analyze the AC/DC hybrid distributed system, thereby effectively improving the accuracy and reliability of calculating the energy utilization rate of the distributed system and constructing the distributed systemIn the operation process, the index system can play a full guiding role, improve the benefits of the distributed system and reduce the energy waste condition in the distributed system; and the accuracy and efficiency of electric loss and energy consumption evaluation in the AC/DC hybrid distributed system are improved.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which is also intended to be covered by the present invention.

Claims (1)

1. Based onThe AC/DC hybrid distributed system comprises an AC/DC power supply system, a distributed energy supply system, a thermodynamic system and an energy storage system; it is characterized by comprising the following steps,

s1, calculating the electrical loss of the AC/DC power supply system; the step S1 specifically includes the steps of,

S11, calculating the line loss of the AC/DC power supply system; the step S11 includes the following specific matters,

s111, calculating statistical line loss; the statistical line loss is the difference between the power supply quantity and the electricity sales quantity, and the calculation formula is that the statistical line loss is = [ (power supply quantity-electricity sales quantity)/power supply quantity ] ×100%;

s112, calculating theoretical line loss; the theoretical line loss is obtained by theoretical calculation according to the parameters of the power supply equipment, the current running mode and the current distribution of the power grid and the load condition;

s113, calculating and managing line loss; the management line loss is the loss electric quantity generated by the factors in the management aspect, and the calculation formula is management line loss = statistical line loss-theoretical line loss;

s114, calculating economic line loss; the theoretical line loss of the line with fixed equipment conditions changes along with the change of the electric load, and the line has the lowest line loss rate, namely the economic line loss, and the corresponding current is called the economic current;

s115, calculating rated line loss; the rated line loss is a line loss index approved by the upper level through measurement and calculation according to the actual line loss of the power grid and combining the power grid structure, the load trend condition and the loss reduction measure arrangement condition in the next assessment period;

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 AC/DC power supply system;

s12, calculating the loss of the power electronic transformer; step S12 includes the following specific details,

s121, calculating hysteresis loss of the power electronic transformer; the hysteresis loss frequency is proportional to the quadratic of the hysteresis coefficient of maximum magnetic flux density, and the losses due to hysteresis under harmonic conditions can be expressed as,

wherein P is _Hn Is hysteresis loss, n is harmonic frequency, U _n Is the n-order harmonic voltage, U ₁ Is the fundamental voltage phi _n The primary phase angle of the voltage of the n-order harmonic is s, and the material coefficient of the iron core is s;

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,

wherein B is _ri For the i-th intra-cell radial magnetic induction intensity, B _zi Is the axial magnetic induction intensity in the ith unit, omega is angular frequency, rho is material resistivity, b, d is wire size, R _i To the core for the center of gravity of the ith unitDistance of line, V _i The volume occupied by the conductor in the ith unit;

s123, calculating 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 the secondary winding coil of the transformer is called basic copper loss, the effective resistance of the lead can be increased to generate additional copper loss due to skin effect and proximity effect caused by a leakage magnetic field, the additional copper loss also comprises eddy current loss generated by an oil tank wall and a metal structural member and internal circulation loss generated by parallel winding of the lead, under the direct current magnetic bias effect, the winding loss is calculated by the formula,

wherein P is _jn R is the winding loss _n (1),R _n (2) The resistances of the primary and secondary windings at the n-th harmonic,is the effective value of the harmonic current flowing through the primary and secondary windings;

s124, adding the hysteresis loss, the eddy current loss and the winding loss to obtain the power electronic transformer loss;

s13, calculating rectifier loss; the rectifier is controlled by PWM, the step S13 includes the following specific matters,

s131, calculating average conduction loss; when the rectifier is on and conducting current, the product of the on saturation voltage and the on current forms a conduction loss, which must be multiplied by the duty cycle factor to find the average loss, which is the average conduction loss of the rectifier as follows,

Wherein P is _SS To average conduction loss, I _CP For outputting electric sineA peak of the stream; v (V) _CE(sat) For peak current I _CP Saturation voltage drop of the lower IGBT; d is the duty cycle; θ is the power factor angle;

s132, calculating average switching loss; the switching loss is the power loss during the transition of the tube on and off, the average switching loss is obtained by multiplying the unit pulse total switching energy by the PWM frequency,

P _SW ＝f _PWM ×(E _SW(on) +E _SW(off) )

wherein P is _SW To average the switching loss, f _PWM For PWM frequency, E _SW(on) And E is _SW(off) The energy of the unit pulse main switch when being opened and closed is respectively;

s14, acquiring the electric loss of the AC/DC power supply system according to the line loss, the power electronic transformer loss and the rectifier loss;

s2, calculating the electrical loss of the distributed energy supply system; the distributed energy supply system comprises a combined cooling heating and power system and photovoltaic distributed equipment; the step S2 includes the following specific matters,

s21, reflecting the electricity consumption of the combined cooling heating and power system through the electricity efficiency and the energy cascade utilization; respectively calculating equivalent electrical efficiency, reduced electrical efficiency, energy cascade utilization rate and energy saving rate of the combined cooling heating power system;

the equivalent electric efficiency is the ratio between the sum of equivalent electric quantity and the primary energy consumption of the combined cooling, heating and power system, the equivalent electric quantity is the electric quantity consumed by respectively converting the cold quantity or the heat quantity in the combined cooling, heating and power system into the same cold quantity or heat quantity output by the corresponding conventional system, the equivalent electric efficiency is calculated as follows,

Wherein eta ₁ For equivalent electrical efficiency, COP _h The heat supply coefficient of the electric heat pump;

the power generation efficiency obtained by calculation is calculated when the energy consumption of the cold and heat output in the combined cooling, heating and power system is the same as that of the reference conventional power generation efficiency, and the calculation formula is as follows,

wherein eta ₂ To reduce the electrical efficiency;

the energy cascade utilization rate comprehensively considers the performance of the cold-hot electric products from the angles of energy taste and cascade utilization, expresses the inequality of different products by using the uniformly quantized energy level taste coefficients as the weight coefficients of the cold, hot and electric, considers the quantity and grade of consumed energy and changes along with the change of comparison conditions, and has the calculation formula of,

wherein eta ₃ The energy cascade utilization rate is used; a is that _e The energy level taste coefficient of electricity; a is that _h Is the thermal energy level taste coefficient; a is that _c Is the thermal energy level taste coefficient; a is that _f Is the energy level taste coefficient of the fuel; ΔE is the energy transfer processA change; Δh is the change in enthalpy of the energy transfer process;

the energy saving rate is that the energy saving condition of the combined cooling heating power system is evaluated by using a thermal economy analysis method based on a first thermodynamic law; the method is characterized in that in a heating period or a cooling period, under the condition of supplying the same heat, cold and electric quantity, the primary energy saving rate of a combined cooling heating and power mode relative to a combined cooling heating and power system is evaluated; the energy saving rate calculation type of the heating period and the cooling period are respectively as follows,

Wherein eta _zh The energy saving rate is used for the heating period; η (eta) _zc The energy saving rate is used for the cold supply period; η (eta) _e The power supply efficiency for the combined supply; η (eta) _h The heat supply efficiency for the combined supply; η (eta) _b The heat supply efficiency of the boiler is improved; COP of _a Is the refrigeration coefficient of the absorption refrigerator; COP of _e Is the refrigeration coefficient of the electric refrigerator;

s22, calculating the loss of an electrical part of the photovoltaic distributed equipment, wherein the loss comprises the reactive loss of a transformer and the effect of the whole efficiency of an inverter;

the reactive power loss of the transformer comprises no-load reactive power loss and load reactive power loss, the calculation formula is as follows,

Q _T ＝Q _O.T +Q _P.T

wherein Q is _T For reactive power loss of transformer, Q _O.T For no-load reactive power loss, Q _P.T U for reactive load loss _d % is the transformer short circuit voltage percentage; i _OT % is the percentage of the no-load current of the transformer; s is S _N.T Rated capacity of the transformer; s is S _T Is the actual load of the transformer; p (P) _PV Is the photovoltaic power transmitted through the transformer;

the efficiency of the inverter directly influences the effective power generation amount and the power generation cost of the photovoltaic power generation system, so that the inverter has the tracking control management function of the maximum power point and changes along with the corresponding change of the radiation capacity of solar energy at any time;

s3, calculating the electrical loss of the thermodynamic system; the step S3 includes the following specific matters,

S31, calculating heat pump electric losses, including air source heat pump system electric losses, water source heat pump system electric losses and ground source heat pump system electric losses;

the power consumption condition of the air source heat pump system in a complete heating/defrosting cycle is regulated, the air source heat pump system supplies heat to the indoor space in the heating stage, the air source heat pump system supplies heat from the indoor space in the defrosting stage, an energy conservation equation of the air source heat pump system is listed,

a. in the heating process, the energy conservation equation is that,

Q _i1 ＝W ₁ +Q _o1

Q _o1 ＝Q _o1,s +Q _o1,l

wherein Q is _o1,s For sensible heat quantity in frosting process, Q _o1,l Is the latent heat of the frosting process;

b. the defrosting process, the air source heat pump system takes heat from the user side or other channels to provide the heat required for the defrosting process, the energy conservation equation of which is,

Q _i2 ＝W ₂ +Q _o2

Q _o2 ＝Q _o2,s +Q _o2,l

wherein Q is _o2,s For sensible heat quantity during defrosting, Q _o2,l Is the latent heat of the defrosting process;

c. actual heating quantity Q of air source heat pump system to user in one heating/defrosting period _h In order to achieve this, the first and second,

Q _h ＝Q _i1 -Q _i2

d. energy efficiency ratio COP of air source heat pump system in heating/defrosting cycle _s In order to achieve this, the first and second,

the compressor, the water source pump and the circulating pump in the water source heat pump system are power consumption equipment;

the relation between the power P of the load, the torque T and the rotating speed n of the compressor is P=Tn/9550 under different rotating speeds n of the motor, and when the rotating speed is n1, the consumed power is P1; when the rotating speed is n2, the consumed power is P2; then P1/p2=n1/n 2, when n1 is the rated rotational speed, P1 is the rated power consumed;

The torque T of the water source pump load is proportional to the square of the rotation speed n, i.e. T= KTn ² The relation between the power P of the load and the rotating speed n is P=Tn/9550=KPn, KP is the power constant of the secondary square load, the power consumed by the water pump is proportional to the cube of the rotating speed, when the water pump is controlled to operate by the frequency converter, the output frequency of the frequency converter is f1, the rotating speed of the water pump is n1, the flow is Q1, and the shaft power of the water pump motor is P1; the output frequency of the frequency converter is f2, the rotation speed of the water pump is n2, the flow rate Q2, the shaft power of the water pump motor is P2, and then Q1: q2=n1: n2, the power consumed by the motor is in direct proportion to the 3-time power of the rotating speed;

the electricity consumption of the ground source heat pump system is 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 electric loss of the ice storage air conditioner, including the loss of ice storage temperature and air supply temperature;

s33, calculating electric loss of the electric heating boiler, wherein the electric loss of the electric heating boiler comprises electric loss in a controller and electric loss in a water pump; the efficiency of the electric heating boiler is

Wherein eta is the efficiency of the electric heating boiler; e, e _{User' s} For outputting electric energy to a user; w is the input electric energy

S34, calculating the electric loss of the water pump, wherein the electric loss of the water pump comprises the electric loss of a boiler feed water pump, a circulating water pump, a condensate pump, a drainage pump, a mortar pump and a speed regulating oil pump, and the water pump is configured to adjust the running speed of the water pump so as to adapt to the requirement of load change;

S4, calculating the electrical loss of the energy storage system; the electric loss of the energy storage system is calculated as the charge and discharge loss of the distributed battery energy storage system,

for the charging situation, let the charging efficiency of the ith distributed battery energy storage system be:

η _i,cha ＝α _i,cha -β _i,cha ·P _i,cha

wherein alpha is _i,cha And beta _i,cha Is a charge constant; p (P) _i,cha To charge power, P _i,cha >0 represents the BESS input power; η (eta) _i,cha Is the charging efficiency;

then the internal power P of the distributed battery energy storage system during charging _i,bat,cha ＝P _i,cha ·η _i,cha The method comprises the steps of carrying out a first treatment on the surface of the Let the power grid electricity price be ρ', the period be DeltaT, the charge loss cost per period P of the distributed battery energy storage system _i,cha,loss The definition is as follows:

P _i,cha,loss ＝ρ'·P _i,cha ·(1-η _i,cha )·ΔT

for the discharging condition, the discharging efficiency of the distributed battery energy storage system is set as follows:

η _i,dch ＝α _i,dch -β _i,dch ·P _i,dch

wherein alpha is _i,dch And beta _i,dch Is a discharge constant; p (P) _i,dch For discharging power, P _i,dch >0 represents the BESS output power; η (eta) _i,dch Is the discharge efficiency;

internal power P of the distributed battery energy storage system upon discharge _i,bat,dch ＝P _i,dch /η _i,dch Cost of discharge loss per cycle C _i,dch,loss Can be defined as:

s5, according to the AC/DC power supply system, the distributed energy supply system and the thermodynamic systemAnd the electric losses of the energy storage system are unified, and the electricity of the alternating current and direct current power supply system, the distributed energy supply system, the thermodynamic system and the energy storage system are respectively acquiredEfficiency and finally obtain the electricity of the AC/DC hybrid distributed system >Efficiency is improved;

the electricity of the alternating current-direct current hybrid distributed systemThe efficiency is the comprehensive energy efficiency evaluation index of the alternating current-direct current hybrid distributed system, the calculation formula is as follows,

wherein eta _AC/DC，E To power the systemEfficiency, P _D For conveying electric quantity of large power grid, P _s For the total amount of thermal radiation received by the photovoltaic cell, P _g Pi is total heat value of natural gas in distributed combustion of natural gas _{Ac/dc power supply} For the power of AC/DC power supply system>Loss of pi _{Distributed power generation} Electric +.>Loss of pi _{Power storage} For electricity of electricity storage system>Loss;

the AC/DC power supply system is powered onThe calculation formula of the efficiency is that

Wherein,for the power of AC/DC power supply system>Efficiency, P _JZ Input power of AC/DC power supply system, +.>Respectively, power distribution line loss, power electronic transformer loss and rectifier loss in an AC/DC power supply system, t ₀ 、t ₁ The start and end time of the alternating current/direct current power supply system;

the distributed power generation system is electricThe calculation formula of the efficiency is that

Wherein,electric +.>Efficiency, P _g For the heavenTotal heating value, P, of natural gas for distributed combustion of natural gas _s The total amount of thermal radiation received for the photovoltaic cell;

∏ _CCHP ＝P _g ·H _s -E _gasout

wherein, pi _CCHP Electricity for distributed generation of natural gas Loss, P _g Total heating value H of natural gas for distributed combustion of natural gas _s Is the high-order heating value of natural gas, E _gasout Generating energy for the distributed generation of natural gas;

∏ _Tur-Gen ＝m·h ₁ -E _out

wherein, pi _Tur-Gen For steam turbines and generatorsLoss, m is the mass of steam fed into the turbine, h ₁ For inputting the enthalpy value of the steam of the turbine, E _out The electric energy is output by the generator;

wherein,losses for a photovoltaic distributed power generation system;

wherein,s is the loss of the solar component _pa P is the heat radiation amount received by the solar component _out Electric energy output for solar energy componentA power;

wherein,for losses of the photovoltaic inverter, +.>Is the power loss of the inverter;

wherein DeltaP _T Delta Q is the active power loss _T For reactive power loss, ΔP ₀ 、ΔQ ₀ As no-load active and reactive power loss, deltaP _S 、ΔQ _S Is the active power and the reactive power of the load, S _ca Is the actual power, S _N.T Rated capacity of the transformer;

the electricity storage system is powered onThe calculation formula of the efficiency is that

Wherein,for electricity of electricity storage system>Efficiency, P _H Total heating value of hydrogen for fuel cell combustion, +.>For energy storage battery loss, < >>E is the loss of the hydrogen fuel cell _{User' s} For outputting electric energy to a user; the distribution line loss, the power electronic transformer loss and the rectifier loss in the AC/DC power supply system are respectively calculated by the following formulas,

Wherein,ΔP, the loss of distribution lines _L In order to achieve a line power loss,

wherein DeltaP _L The power loss of the circuit, lambda is a power factor, U is a circuit running voltage, I is a current flowing through the circuit, R is a circuit resistance, rho is a circuit resistivity, l is a circuit length, and A is a circuit sectional area;

wherein,for losses of the power electronic transformer, +.>P _Hn 、P _E Power loss for each part of the power electronic transformer;

wherein,p, the loss of rectifier _ss 、P _SW Is the power loss of the power switch IGBT.