CN110808608A - Method and system for evaluating frequency modulation and voltage regulation capability of large-scale new energy participating receiving-end power grid - Google Patents

Method and system for evaluating frequency modulation and voltage regulation capability of large-scale new energy participating receiving-end power grid Download PDF

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CN110808608A
CN110808608A CN201911006052.9A CN201911006052A CN110808608A CN 110808608 A CN110808608 A CN 110808608A CN 201911006052 A CN201911006052 A CN 201911006052A CN 110808608 A CN110808608 A CN 110808608A
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power
frequency modulation
wind
photovoltaic
capacity
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孙蓉
陈兵
吕振华
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
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Abstract

The invention discloses a method and a system for evaluating the frequency modulation and voltage regulation capacity of a large-scale new energy participating receiving-end power grid, which solve the problem of evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid, collect historical data of a wind power plant and a photovoltaic power station, construct a probability distribution model of wind speed and illumination intensity by adopting a Gaussian mixture model, and establish a frequency modulation capacity evaluation model and an inertia time constant model for the frequency modulation capacity evaluation; a voltage regulating capacity evaluation model is established for the voltage regulating capacity evaluation; according to the invention, different frequency and voltage regulation evaluation models are respectively established for the wind power generation system and the photovoltaic power generation system, so that the evaluation models are more accurate. The method can effectively solve the problem that the large-scale new energy participates in the frequency modulation and voltage regulation capability evaluation of the receiving-end power grid, has the advantages of comprehensiveness, accuracy and practicability, can provide technical support for the virtual synchronous control technology of the large-scale new energy, and solves the problem that the power grid lacks support capability after the high-proportion new energy is accessed.

Description

Method and system for evaluating frequency modulation and voltage regulation capability of large-scale new energy participating receiving-end power grid
Technical Field
The invention belongs to the technical field of power system new energy grid connection active regulation and analysis, and particularly relates to a method and a system for evaluating the frequency modulation and voltage regulation capacity of a large-scale new energy participating receiving-end power grid.
Background
With the rapid development of new energy, the power electronization characteristics of the power system are more prominent, and greater pressure is brought to the safe and stable operation of the power system. The power electronic device adopted by the new energy has technical advantages, but almost has no rotational inertia, is difficult to participate in power grid regulation, and cannot provide necessary voltage and frequency support for the power grid. In order to improve the operating characteristics of the new energy unit, enhance the new energy consumption capability and relieve the operating pressure of a power grid, the new energy unit is urgently required to have certain active supporting capability. At present, research on new energy is mainly focused on new energy at a transmitting end, and for a receiving-end power grid, with the large-scale development of photovoltaic and wind power, the further increase of external power can significantly reduce the self-regulation capacity of the receiving-end power grid, so that how to deal with serious power grid faults such as extra-high voltage direct-current bipolar blocking and how to guarantee the safe and stable operation level needs to be researched on the influences and countermeasures of large-scale photovoltaic and wind power access on peak regulation, frequency regulation and voltage regulation of the receiving-end power grid. The Virtual Synchronous Generator (VSG) technology improves a control system of a new energy power generation device, so that the new energy power generation device has frequency and voltage regulation characteristics similar to those of a conventional synchronous unit, and the problem that a power grid lacks support capability after a high proportion of new energy is accessed is solved.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a method and a system for evaluating the frequency and voltage regulation capability of a large-scale new energy participating receiving-end power grid aiming at the defects of the prior art, and solves the problem that the frequency and voltage regulation capability of the large-scale new energy participating receiving-end power grid is difficult to evaluate.
The technical scheme is as follows: the invention provides a method for evaluating the frequency modulation and voltage regulation capacity of a large-scale new energy participating receiving-end power grid, which comprises the following steps of:
the wind speed is divided into intervals according to wind speed samples of each wind power plant, and the wind power plant frequency modulation capacity is evaluated through a wind power generation frequency modulation capacity evaluation model;
evaluating the frequency modulation capacity of the photovoltaic power generation system by the photovoltaic power generation frequency modulation capacity evaluation model through the illumination intensity sample of the photovoltaic power station;
calculating an equivalent inertia time constant of the power system;
evaluating the voltage regulating capacity of the wind power plant through a wind power generation voltage regulating capacity evaluation model;
evaluating the voltage regulating capacity of the photovoltaic power station through a photovoltaic power generation voltage regulating capacity evaluation model;
the wind speed samples of the wind power plants and the illumination intensity samples of the photovoltaic power stations are generated by adopting a Gaussian mixture model to construct a probability distribution model of wind speed and illumination intensity according to historical wind speed and illumination intensity data of the wind power plants and the photovoltaic power stations; the new energy generator is controlled by adopting a virtual synchronous generator technology.
The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid is characterized by comprising the following steps of: the Gaussian mixture model is used for constructing a probability distribution model of wind speed and illumination intensity:
Figure BDA0002242802670000021
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000022
is the probability distribution of the kth part; omegakIs a Gaussian mixture functionWeights of k parts; mu.skAnd σkRespectively, the expected and standard deviation of the kth part; n is a radical oftFor the number of components to fit, k is 1,2 … NtX is a random variable, Φ is the illumination intensity or the wind speed, wherein the weight satisfies the following constraint:
the method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid is characterized by comprising the following steps of: the wind power plant frequency modulation capacity evaluation method comprises the following steps of carrying out interval division on wind speed through wind speed samples of each wind power plant, and evaluating the frequency modulation capacity of the wind power plant through a wind power generation frequency modulation capacity evaluation model, wherein the method specifically comprises the following steps:
the wind speed is divided into four sections: the method comprises the following steps of low wind speed, medium wind speed and high wind speed, and is specifically divided into:
Figure BDA0002242802670000024
under the lower wind speed section i ═ 1, adopt the simulation inertia control mode, can be used for increasing the kinetic energy of electric power output for a short time with fan rotating part storage and convert into fan frequency modulation power:
in the formula, PijThe frequency modulation capacity of a jth fan under the ith wind speed type is J, and the J is the rotational inertia of a rotating part of the fan; omegaAThe rotating speed of the fan when the fan participates in the frequency modulation starting is set; omegaMPPTThe rotating speed of the fan when the fan outputs the maximum power is shown as η, the conversion efficiency from kinetic energy to electric energy is shown as i, the wind speed types of the fan are lower speed, middle speed and high speed 3, and j is the serial number of the fan under the wind speed i type;
and (3) under the medium wind speed section, i is 2, the optimal fan load reduction driving point is obtained by combining the simulation inertia control and the overspeed control, and the frequency modulation capacity of the fan at the moment is as follows:
Figure BDA0002242802670000031
in the formula, PMPPTMaximum power, omega, output by the fanrIs the rotational speed, P, of the fan rotorbThe expression is shown as the following formula:
Figure BDA0002242802670000032
in the formula, kbA coefficient which represents that the output power of the fan and the rotating speed of the rotor are approximately 3 times;
when the high wind speed section i is equal to 3, adopting pitch angle control, wherein the frequency modulation capacity of the fan at the moment is as follows:
Pij＝Pmmax-Pmmin(7)
wherein, PmmaxThe maximum aerodynamic power which can be captured by the fan is represented, and the calculation method is shown as the following formula:
Figure BDA0002242802670000033
in the formula, CpmaxRepresenting the maximum power coefficient of the fan; λ represents tip speed ratio, λ ═ ω R1/vijOmega is the angular velocity of the fan blade, R1Representing fan sweep radius, vijThe speed of a fan blade of a jth fan under the ith wind speed type is β, the rho is the air density, A represents the swept area of the fan blade;
Pmminthe minimum aerodynamic power captured by the fan is represented, and the calculation method is as follows:
Figure BDA0002242802670000034
in the formula, CpminRepresenting a minimum power coefficient of the fan;
obtaining the total frequency modulation capacity of the wind power plant:
Figure BDA0002242802670000036
in the formula, PfRepresenting the total frequency modulation capacity of the wind power place; n represents the number of fans in the wind farm; i denotes the type of wind speed of the fan, NRIndicating the total number of fans in the ith interval, ξijIs the probability that the jth fan is in the i-type wind speed interval, pijRepresenting the frequency modulation capacity of the jth fan in the i-type wind speed interval.
The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid is characterized by comprising the following steps of: through photovoltaic power plant illumination intensity sample, photovoltaic power generation frequency modulation capacity evaluation model evaluates the frequency modulation capacity of photovoltaic power generation system, specifically:
when the voltage of the photovoltaic array is U, the current of the maximum power point of the corresponding photovoltaic array is I:
Figure BDA0002242802670000041
wherein: i isscFor short-circuit current of photovoltaic array, VocFor photovoltaic array open circuit voltage, Im,VmRespectively the maximum power point current and the voltage of the photovoltaic array,
C2＝(Vm/Voc-1)/ln(1-Im/Isc) (14)
when considering the effect of the change in solar radiation,
Figure BDA0002242802670000043
wherein the content of the first and second substances,
DI＝(R/Rref-1)·Isc(16)
DV＝-Rs·DI (17)
wherein R is the luminous intensity, RrefAs reference value of solar radiation, RsIs the series resistance of the photovoltaic module;
the power of the photovoltaic array at any solar radiation intensity is:
Figure BDA0002242802670000044
when the MPPT point is controlled to operate at the maximum power, dP/dU is equal to 0, and the voltage U of the maximum power point of the photovoltaic array is obtainedmaxMaximum power P of photovoltaic arrayMPPTThe following equation is obtained:
PMPPT＝Imax·Umax(19)
Imaxa current that is the maximum power point of the photovoltaic array;
the frequency modulation capacity of the photovoltaic is expressed as:
in the formula, PgThe method comprises the following steps of (1) establishing a photovoltaic power generation frequency modulation capacity evaluation model for photovoltaic frequency modulation capacity, wherein epsilon is the percentage of the frequency modulation capacity to the maximum output power;
Figure BDA0002242802670000052
represents the maximum power of the ith photovoltaic array, NlFor the number of photovoltaic arrays, l 1,2l。
The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid is characterized by comprising the following steps of: calculating an equivalent inertia time constant of the power system, specifically:
the inertia constant H of the synchronous generator is shown as follows:
Figure BDA0002242802670000053
in the formula, WkThe kinetic energy is the rotational kinetic energy of the new energy generator at the rated rotating speed; sNRated capacity of the new energy generator; j is the rotor moment of inertia, Ω0Synchronizing the angular velocity for the generator;
in a short time, the calculation formula of the equivalent inertia time constant is as follows:
in the formula, Hi1And Si1Are respectively a unit i1Inertia time constant and capacity of i1＝1,2,...,m+nThe system comprises a synchronous generator and a new energy source unit participating in primary frequency response, n and m respectively represent the number of the synchronous generator and the new energy source generator, and SN,sRepresenting the total capacity of the generator to generate power.
Virtual inertia time constant H of equivalent synchronous generator of power systemeqThe solution is solved by the following formula:
Figure BDA0002242802670000055
in the formula, Hsi2For a synchronous generator i2Constant of inertia time of i2＝1,2,...,n；Hw-eqj2For new energy generator j2Inertia time constant j of2＝1,2,...,m；SNi2For a synchronous generator i2Rated capacity of (d); sNwj2For new energy generator j2The rated capacity of (a).
The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid is characterized by comprising the following steps of: the wind power plant voltage regulation capacity is evaluated through a wind power generation voltage regulation capacity evaluation model, and the method specifically comprises the following steps:
will be 0 to [ V ]0]+1 equal division by k1A region, [ V ]0]Is less than the natural wind speed V0Is selected as the maximum integer of k1＝[V0]+1；
Natural wind speed is V0In the interval (i)v-1,iv]The ratio P of the inner generator to the total generatorivComprises the following steps:
Figure BDA0002242802670000061
iv＝1,2,…,k1；NAthe total number of wind driven generators;
and (3) solving the upper and lower reactive power limits of the wind driven generator after the wind speed is known:
Figure BDA0002242802670000062
in the formula, nivIs the interval (i)v-1,iv]Number of fans, PsActive power of the wind driven generator; qmaxAnd QminThe upper limit and the lower limit of the reactive power regulation of the wind driven generator are respectively set; u shapesIs the stator voltage peak value of the wind driven generator; xsIs the stator reactance of the wind driven generator; xmIs the excitation reactance of the wind driven generator; i isrmaxIs the maximum value of the current on the rotor side; q0The internal reactive power consumption of the power system is realized;
at a natural wind speed of V0And the upper and lower boundaries of the overall reactive power regulation range of the wind power plant are as follows:
Figure BDA0002242802670000063
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000064
and
Figure BDA0002242802670000065
the upper and lower boundaries are respectively the total wind power reactive power regulation of the wind power plant; k is a radical oflIs the reactive loss coefficient; m is1The total number of fans; p is a radical ofivFor a natural wind speed V0Lower wind speed interval (i)v-1,iv]The proportion of the inner fans to the total number of the fans,respectively represent the ithvAnd the upper limit and the lower limit of the interval wind driven generator are adjusted in a reactive mode.
The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid is characterized by comprising the following steps of: the photovoltaic power station voltage regulation capacity is evaluated through the photovoltaic power generation voltage regulation capacity evaluation model, and the method specifically comprises the following steps:
knowing the illumination intensity of each photovoltaic power generation system, for a solar photovoltaic power generation system, assuming that a solar array has M modules, the area of each module is S, the photoelectric conversion efficiency is γ, and R is the illumination intensity, the active power output P of the solar photovoltaic isrComprises the following steps:
Pr＝R·M·S·γ (26)
the maximum reactive power regulation range of the photovoltaic generator is obtained through the relation of active power, reactive power and power factor:
Figure BDA0002242802670000071
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000072
the upper and lower boundaries of the q-th photovoltaic array reactive power regulation are respectively,
Figure BDA0002242802670000073
is the maximum adjustable power factor; q0The reactive power required to be consumed by the photovoltaic power generation system is represented.
For N1Photovoltaic generator set, the maximum reactive power control range can be expressed as:
Figure BDA0002242802670000074
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000075
andthe upper and lower boundaries of the reactive power regulation of the photovoltaic power generation system are q ═ 1,2, …, N1。
A large-scale new energy participation receiving end power grid frequency modulation and voltage regulation capability assessment system is characterized in that: the method comprises the following steps:
the wind power plant frequency modulation capacity evaluation module is used for carrying out interval division on the wind speed through wind speed samples of each wind power plant and evaluating the frequency modulation capacity of the wind power plant through a wind power generation frequency modulation capacity evaluation model;
the photovoltaic power generation frequency modulation capacity evaluation module is used for evaluating the frequency modulation capacity of the photovoltaic power generation system through the photovoltaic power station illumination intensity sample and the photovoltaic power generation frequency modulation capacity evaluation model;
the equivalent inertia time constant calculation module is used for calculating an equivalent inertia time constant of the power system;
the wind power plant voltage regulation capacity evaluation module is used for evaluating the voltage regulation capacity of the wind power plant through the wind power generation voltage regulation capacity evaluation model;
the photovoltaic power station voltage regulation capacity evaluation module is used for evaluating the voltage regulation capacity of the photovoltaic power station through the photovoltaic power generation voltage regulation capacity evaluation model;
the wind speed samples of the wind power plants and the illumination intensity samples of the photovoltaic power stations are generated by adopting a Gaussian mixture model to construct a probability distribution model of wind speed and illumination intensity according to historical wind speed and illumination intensity data of the wind power plants and the photovoltaic power stations; the new energy generator is controlled by adopting a virtual synchronous generator technology.
Has the advantages that: the invention has the following advantages and technical effects:
(1) the method for evaluating the frequency modulation and voltage regulation capability of the large-scale new energy participating receiving-end power grid has the advantages of comprehensiveness, accuracy and practicability;
(2) the frequency modulation capacity evaluation model is established by combining with a related virtual synchronization technology, so that the new energy frequency modulation capacity can be accurately obtained, the frequency modulation capacity is increased along with the increase of permeability, meanwhile, the wind power frequency modulation capacity has a reverse peak regulation characteristic, the photovoltaic frequency modulation capacity exists only in the daytime, and cannot participate in frequency modulation at night;
(3) the system equivalent inertia time constant evaluation model is established through a virtual synchronization technology, the system equivalent inertia time constant can be accurately obtained, and the system equivalent inertia time constant is gradually reduced when the scale of the system accessing new energy is larger and larger;
(4) the voltage regulation capacity evaluation model is established by combining with a related virtual synchronization technology, the new energy voltage regulation capacity can be accurately obtained, the wind power reactive power regulation range is continuously increased along with the continuous increase of the permeability of new energy, the photovoltaic voltage regulation capacity only exists in the daytime, and the photovoltaic voltage regulation capacity cannot participate in voltage regulation at night;
(5) the method can provide technical support for the virtual synchronous control technology of the large-scale new energy, and solves the problem that a power grid lacks support capability after the high-proportion new energy is accessed.
Drawings
FIG. 1 is a flow chart of a method in an embodiment of the invention;
FIG. 2 is a diagram of an improved IEEE-57 node exemplary system architecture;
FIG. 3 is a wind speed interval division diagram of a wind farm;
FIGS. 4-6 illustrate wind power tuning capacity at low, medium and high permeability;
FIG. 7 is a graph of photovoltaic frequency modulation capacity at different permeabilities;
FIG. 8 is a graph of the equivalent inertial time constant for different permeability systems;
FIGS. 9-11 show the wind power reactive voltage regulation capacity limit ranges of the system at low, medium and high permeabilities.
Fig. 12-14 are plots of the photovoltaic reactive voltage regulation capacity limit ranges for the system at low, medium, and high permeabilities.
Detailed Description
The practice of the present invention is further illustrated, but not limited, by the following examples and figures.
As shown in fig. 1, a method for evaluating the frequency modulation and voltage regulation capability of a large-scale new energy participating receiving-end power grid includes the following steps:
step 1: according to historical wind speed and illumination intensity data of the wind power plant and the photovoltaic power station, a Gaussian Mixture Model (GMM) is adopted to construct a probability distribution model of the wind speed and the illumination intensity, and wind speed samples and photovoltaic power station illumination intensity samples of each wind power plant are generated;
step 2: the wind speed is divided into intervals according to wind speed samples of each wind power plant, and a wind power generation frequency modulation capacity evaluation model is constructed to evaluate the frequency modulation capacity of the wind power plant;
and step 3: establishing a photovoltaic power generation frequency modulation capacity evaluation model to evaluate the frequency modulation capacity of the photovoltaic power generation system through the illumination intensity sample of the photovoltaic power station;
and 4, step 4: the new energy generator is controlled by adopting a virtual synchronous generator technology, and an equivalent inertia time constant of a system is calculated;
and 5: constructing a wind power generation voltage regulation capacity evaluation model to evaluate the voltage regulation capacity of the wind power plant;
step 6: building a photovoltaic power generation voltage regulation capacity evaluation model to evaluate the voltage regulation capacity of the photovoltaic power station;
step 1, constructing a probability distribution model of wind speed of a wind power plant and illumination intensity of a photovoltaic power station by adopting a Gaussian mixture model:
the GMM is a Gaussian mixture model formed by linearly combining a plurality of Gaussian distributions, theoretically, the GMM can smooth any probability distribution, and any probability distribution function can be expressed as a probability distribution model of wind speed and illumination intensity:
Figure BDA0002242802670000091
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000092
is the probability distribution of the kth part; omegakA weight of a kth part of a Gaussian mixture function; mu.skAnd σkRespectively, the expected and standard deviation of the kth part; n is a radical oftFor the number of components to fit, k is 1,2 … NtX is a random variable, Φ is the illumination intensity or the wind speed, wherein the weight satisfies the following constraint:
Figure BDA0002242802670000093
the key point of adopting the GMM method is to determine the parameter N thereint、ωk、μk、σkThe most common method currently is to use measurement data and an expectation maximization method. And generating wind speed samples of each wind power plant and illumination intensity samples of the photovoltaic power plants by using the probability distribution models of the wind speed and the illumination intensity, namely random numbers which accord with the probability distribution function. Step 2, carrying out interval division on the wind speed, constructing a wind power generation frequency modulation capacity evaluation model, adopting different frequency modulation capacity evaluation methods under different wind speeds, and finally evaluating the total frequency modulation capacity of the wind power plant; the method comprises the following steps:
step 201: according to the VSG control technology, fans in different wind speed intervals are divided, and the method is divided into four sections: low wind speed, medium wind speed, high wind speed. The calculation models of the frequency modulation capacity at different wind speed sections are different, the low wind speed does not participate in the frequency modulation, and the calculation models are specifically divided into the following steps:
Figure BDA0002242802670000101
step 202: under the lower wind speed section i ═ 1, adopt the simulation inertia control mode, can be with the kinetic energy that can be used for increasing electric power output for a short time that fan rotating part stored convert into fan frequency modulation power:
Figure BDA0002242802670000102
in the formula, PijThe frequency modulation capacity of a jth fan under the ith wind speed type is J, and the J is the rotational inertia of a rotating part of the fan; omegaAThe rotating speed of the fan when the fan participates in the frequency modulation starting is set; omegaMPPTThe rotating speed of the fan when the fan outputs the maximum power is shown as η, the conversion efficiency from kinetic energy to electric energy is shown as i, the wind speed type (lower speed, medium speed and high speed 3 types) of the fan is shown as i, and the serial number of the fan under the wind speed i type is shown as j.
Step 203: and (3) under the medium wind speed section, i is 2, the optimal fan load reduction driving point is obtained by combining the simulation inertia control and the overspeed control, and the frequency modulation capacity of the fan at the moment is as follows:
Figure BDA0002242802670000103
in the formula, PMPPTMaximum power, omega, output by the fanrIs the rotational speed, P, of the fan rotorbThe expression is shown as the following formula:
Figure BDA0002242802670000104
in the formula, kbAnd the coefficient which represents the output power of the fan and the rotating speed of the rotor is approximately 3.
Step 204: when the high wind speed section i is equal to 3, adopting pitch angle control, wherein the frequency modulation capacity of the fan at the moment is as follows:
Pij＝Pmmax-Pmmin(35)
wherein, PmmaxThe maximum aerodynamic power (mechanical power) which can be captured by the fan is represented, and the calculation method is represented as follows:
Figure BDA0002242802670000105
in the formula, CpmaxRepresenting the maximum power coefficient of the fan; λ represents a tip speed ratio (λ ═ ω R)1/vijOmega is the angular velocity of the fan blade, R1Representing fan sweep radius, vijThe speed of a fan blade of a jth fan under the ith wind speed type is β, the rho is the air density, A represents the swept area of the fan blade;
Pmminthe minimum aerodynamic power (mechanical power) captured by the fan is represented, and the calculation method is as follows:
Figure BDA0002242802670000111
in the formula (I), the compound is shown in the specification,Cpminrepresenting the minimum power coefficient of the fan.
The fan frequency modulation capacity pijNamely a wind power generation frequency modulation capacity evaluation model;
step 205: the total frequency modulation capacity of the wind power plant can be obtained through the calculation:
Figure BDA0002242802670000112
Figure BDA0002242802670000113
in the formula, PfRepresenting the total frequency modulation capacity of the wind power place; n represents the number of fans in the wind farm; i represents the wind speed type of the fan (lower speed, medium speed, high speed 3 types), NRIndicating the total number of fans in the ith interval, ξijIs the probability that the jth fan is in the i-type wind speed interval, pijThe frequency modulation capacity of the j-th fan in the i-type wind speed interval is represented, and the probability sum of each wind speed interval is 1 in the formula (11).
Step 3, a photovoltaic power generation frequency modulation capacity evaluation model is constructed to evaluate the frequency modulation capacity of the photovoltaic power generation system through the illumination intensity sample of the photovoltaic power station; the method specifically comprises the following steps:
for photovoltaic power generation, for a photovoltaic array, set under reference conditions (normal temperature, constant humidity, etc.), IscFor short-circuit current of photovoltaic array, VocFor photovoltaic array open circuit voltage, Im,VmThe current and the voltage of the maximum power point of the photovoltaic array are respectively, when the voltage of the photovoltaic array is U, the current of the maximum power point of the corresponding photovoltaic array is I:
Figure BDA0002242802670000114
wherein:
Figure BDA0002242802670000115
C2＝(Vm/Voc-1)/ln(1-Im/Isc) (42)
when considering the effect of the change in solar radiation,
Figure BDA0002242802670000116
wherein the content of the first and second substances,
DI＝(R/Rref-1)·Isc(44)
DV＝-Rs·DI (45)
wherein R is the luminous intensity, RrefFor reference solar radiation, it is generally taken to be 1kw/m2；RsIs the series resistance of the photovoltaic module.
The power of the photovoltaic array at any solar radiation intensity is:
Figure BDA0002242802670000121
when the Maximum Power Point (MPPT) runs, dP/dU is 0, and the voltage U of the maximum power point of the photovoltaic array can be obtainedmaxThereby the maximum power P of the photovoltaic arrayMPPTThe following equation is obtained:
PMPPT＝Imax·Umax(47)
Imaxthe current is the maximum power point of the photovoltaic array.
In summary, the frequency modulation capacity of the photovoltaic is expressed as:
Figure BDA0002242802670000122
in the formula, PgThe method comprises the following steps of (1) establishing a photovoltaic power generation frequency modulation capacity evaluation model for photovoltaic frequency modulation capacity, wherein epsilon is the percentage of the frequency modulation capacity to the maximum output power;
Figure BDA0002242802670000123
denotes the maximum of the l-th photovoltaic arrayPower, NlFor the number of photovoltaic arrays, l 1,2l。
Step 4, the new energy generator is controlled by adopting a virtual synchronous generator technology, and an equivalent synchronous generator virtual inertia time constant of the power system is calculated, wherein the method comprises the following steps:
the constant H between inertia of the synchronous generator is an important concept, which is the synchronous angular velocity Ω of the generator0The ratio H of the kinetic energy of the lower unit rotor during rotation to the rated capacity of the generator is shown as the following formula:
Figure BDA0002242802670000124
in the formula, WkThe kinetic energy is the rotational kinetic energy of the new energy generator at the rated rotating speed; sNRated capacity of the new energy generator; j is the rotor moment of inertia.
When the system frequency changes, the virtual synchronous machine of the new energy machine set adjusts the pitch angle to control the standby storage or release and provide a power supporting function. Therefore, in a short time, the calculation formula of the equivalent inertia time constant is as follows:
Figure BDA0002242802670000131
in the formula, Hi1And Si1Are respectively a unit i1Inertia time constant and capacity of i1＝1,2,...,m+nThe system comprises a synchronous generator and a new energy source unit participating in primary frequency response, n and m respectively represent the number of the synchronous generator and the new energy source generator, and SN,sRepresenting the total capacity of the generators (including the synchronous generator new energy generator) to generate power.
Inertia time constants of conventional power plants (units) in a power system are determined, and virtual inertia time constants H of equivalent synchronous generators of the power system are determined for a wind power plant to which virtual inertia control is appliedeqThe solution can be solved by the following formula:
Figure BDA0002242802670000132
in the formula, Hsi2Is the inertia time constant, i, of the synchronous generator i22＝1,2,...,n；Hw-eqj2For new energy generator j2Inertia time constant j of2＝1,2,...,m；SNi2For a synchronous generator i2Rated capacity of (d); sNwj2For new energy generator j2The rated capacity of (a).
Step 5, a wind power generation voltage regulation capacity evaluation model is built to evaluate the voltage regulation capacity of the wind power plant; the method comprises the following steps:
step 501: will be 0 to [ V ]0]+1 equal division by k1A region, [ V ]0]Is less than the natural wind speed V0Is generally chosen to be k1＝[V0]+1；
Step 502: natural wind speed is V0In the interval (i)v-1,iv]The ratio P of the inner generator to the total generatorivComprises the following steps:
Figure BDA0002242802670000133
iv＝1,2,…,k1；NAthe total number of wind driven generators;
step 503: after the wind speed is known, the upper and lower reactive limits of the wind driven generator can be obtained:
Figure BDA0002242802670000134
in the formula, nivIs the interval (i)v-1,iv]Number of fans, PsActive power of the wind driven generator; qmaxAnd QminThe upper limit and the lower limit of the reactive power regulation of the wind driven generator are respectively set; u shapesIs the stator voltage peak value of the wind driven generator; xsIs the stator reactance of the wind driven generator; xmIs the excitation reactance of the wind driven generator; i isrmaxIs the maximum value of the current on the rotor side; q0The internal reactive power consumption of the power system is realized.
Step 504: at a natural wind speed of V0When the temperature of the water is higher than the set temperature,the upper and lower bounds of the overall reactive power regulation range of the wind power plant are as follows:
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000142
and
Figure BDA0002242802670000143
the upper and lower boundaries are respectively the total wind power reactive power regulation of the wind power plant; k is a radical oflIs the reactive loss coefficient; m is1The total number of fans; p is a radical ofivFor a natural wind speed V0Lower wind speed interval (i)v-1,iv]The proportion of the inner fans to the total number of the fans,
Figure BDA0002242802670000144
respectively represent the ithvAnd the upper limit and the lower limit of the interval wind driven generator are adjusted in a reactive mode.
Step 6, building a photovoltaic power generation voltage regulation capacity evaluation model to evaluate the voltage regulation capacity of the photovoltaic power station; the method comprises the following steps:
knowing the illumination intensity of each photovoltaic power generation system, for a solar photovoltaic power generation system, assuming that a solar array has M modules, the area of each module is S, the photoelectric conversion efficiency is γ, and R is the illumination intensity, the active power output P of the solar photovoltaic isrComprises the following steps:
Pr＝R·M·S·γ (54)
the maximum reactive power regulation range of the photovoltaic generator can be obtained through the relation of active power, reactive power and power factor:
Figure BDA0002242802670000145
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000146
the upper and lower boundaries of the q-th photovoltaic array reactive power regulation are respectively,
Figure BDA0002242802670000147
is the maximum adjustable power factor; q0The reactive power required to be consumed by the photovoltaic power generation system is represented.
For N1Photovoltaic generator set, the maximum reactive power control range can be expressed as:
Figure BDA0002242802670000148
in the formula (I), the compound is shown in the specification,
Figure BDA0002242802670000151
andthe upper and lower boundaries of the reactive power regulation of the photovoltaic power generation system are q ═ 1,2, …, N1。
A large-scale new energy participation receiving end power grid frequency modulation and voltage regulation capability evaluation system comprises:
the wind power plant frequency modulation capacity evaluation module is used for carrying out interval division on the wind speed through wind speed samples of each wind power plant and evaluating the frequency modulation capacity of the wind power plant through a wind power generation frequency modulation capacity evaluation model;
the photovoltaic power generation frequency modulation capacity evaluation module is used for evaluating the frequency modulation capacity of the photovoltaic power generation system through the photovoltaic power station illumination intensity sample and the photovoltaic power generation frequency modulation capacity evaluation model;
the equivalent inertia time constant calculation module is used for calculating an equivalent inertia time constant of the power system;
the wind power plant voltage regulation capacity evaluation module is used for evaluating the voltage regulation capacity of the wind power plant through the wind power generation voltage regulation capacity evaluation model;
the photovoltaic power station voltage regulation capacity evaluation module is used for evaluating the voltage regulation capacity of the photovoltaic power station through the photovoltaic power generation voltage regulation capacity evaluation model;
the wind speed samples of the wind power plants and the illumination intensity samples of the photovoltaic power stations are generated by adopting a Gaussian mixture model to construct a probability distribution model of wind speed and illumination intensity according to historical wind speed and illumination intensity data of the wind power plants and the photovoltaic power stations; the new energy generator is controlled by adopting a virtual synchronous generator technology.
According to the method, historical data of the wind power plant and the photovoltaic power station are collected, on the basis, a probability distribution model of wind speed and illumination intensity is built by adopting a Gaussian mixture model, and wind speed samples of the wind power plant and illumination intensity samples of the photovoltaic power station are generated, namely random numbers which accord with probability distribution functions. Then, a frequency modulation capacity evaluation model and an inertia time constant model are established for frequency modulation capacity evaluation; then, a voltage regulation capacity evaluation model is established for the voltage regulation capacity evaluation. Because the wind power generation control system and the photovoltaic power generation control system are greatly different, different frequency and voltage regulation evaluation models are respectively established for the wind power generation system and the photovoltaic power generation system, so that the evaluation models are more accurate. The method can effectively solve the problem that the large-scale new energy participates in the frequency modulation and voltage regulation capability evaluation of the receiving-end power grid, has the advantages of comprehensiveness, accuracy and practicability, can provide technical support for the virtual synchronous control technology of the large-scale new energy, and solves the problem that the power grid lacks support capability after the high-proportion new energy is accessed.
The specific embodiment is as follows:
1. example of evaluation of frequency modulation capability
The analysis of the frequency modulation capability evaluation algorithm adopts an IEEE-57 node algorithm, as shown in figure 2. In the example, the wind power generation system is connected to the nodes 33, 44, 49 and 50, the photovoltaic power generation system is connected to the nodes 51, 52, 56 and 57, the frequency modulation effect is considered, and different permeability scenes are set according to the following conditions: low permeability (18.95%), medium permeability (36.19%), high permeability (58.39%). The specific parameters of the fan and the photovoltaic module are as shown in table 1:
TABLE 1 Fan and photovoltaic Assembly detailed parameter Table
Figure BDA0002242802670000161
(1) Wind power frequency modulation capacity
The wind power frequency modulation reserves the spare capacity by adopting different control modes in different wind speed intervals, so that the wind speed should be divided into intervals at first, as shown in fig. 3. The wind speed is different due to different geographical positions of different wind farms in each time period, so that different VSG control modes are required: the simulation inertia control is adopted at a lower wind speed, the overspeed control and the simulation inertia control are combined at a medium wind speed, and the pitch angle control is adopted at a high wind speed. Fig. 4 to 6 show the total new energy frequency modulation capacity under different permeabilities, and it can be seen from the graphs that the wind power frequency modulation capacity is provided at 24 times a day, so that frequency modulation can be performed at any time, and the wind power frequency modulation capacity increases with the increase of the permeability: the low to medium permeability increases by about 100%, and the medium to high permeability increases by about 150%. It can also be seen from the 24-moment frequency modulation capacity that the wind power anti-peak-shaving characteristic is met.
(2) Photovoltaic frequency modulation capacity
The frequency modulation mode of the photovoltaic participation system is simple relative to wind power, maximum power point tracking control is adopted under the normal condition, when the system needs to be reserved for standby, the system can be prevented from operating at the maximum power point by changing voltage, and when the system needs to perform frequency modulation, the voltage is changed again to increase the output active power. The tuning capacity at different permeabilities is shown in fig. 7. Compared with wind power frequency modulation, due to the illumination characteristic, the photovoltaic frequency modulation capacity exists only in 6-19 days, and the larger the illumination intensity is, the larger the frequency modulation capacity is: when the permeability is low, the maximum frequency modulation capacity is 5.81 MW; when the permeability is medium, the maximum frequency modulation capacity is 11.60 MW; at high permeability, the maximum tuning capacity is 17.43 MW. But compare in the complicated control mode of wind-powered electricity generation, the cost of photovoltaic frequency modulation is little, and application scope is wide, consequently need add photovoltaic and wind-powered electricity generation and carry out the frequency modulation standby simultaneously in electric power system, improvement electric power system's that can be better stability.
(3) Equivalent time constant of inertia
The power system inertia provides a short-term power support that can respond to changes in the system frequency, having the effect of preventing the system frequency from falling rapidly. The rotational inertia in the system is mainly provided by a synchronous generator when the system frequency is highWhen the rate fluctuates, the synchronous generator rotor releases its rotational kinetic energy to track the frequency change, so in the system frequency analysis, the inertia time constant H of the synchronous generator is an important concept, which is the synchronous angular velocity omega of the generator0The ratio of the kinetic energy of the lower unit rotor during rotation to the rated capacity of the generator. Assuming that the inertia time constant of the wind turbine and the photovoltaic generator is 5 seconds, the equivalent inertia time constant of the wind turbine and the photovoltaic generator at different permeabilities is shown in fig. 8. It can be known from the figure that when the system is connected with new energy in a larger scale, the equivalent inertia time constant of the system gradually decreases, that is, the capacity of preventing the frequency of the system from decreasing is reduced, which increases the operation risk of the system, and if the new energy generator does not adopt the VSG technology, the equivalent inertia time constant of the system decreases more, which is particularly obvious at high permeability, and the equivalent inertia time constant of the system can increase by 2.77 seconds by adopting the VSG.
2. Example of evaluation of pressure regulating capability
The analysis of the voltage regulation capability evaluation algorithm adopts an IEEE-57 node algorithm, as shown in figure 2. In the example, the wind power system is connected to nodes 33, 44, 49, 50, and the photovoltaic power system is connected to nodes 51, 52, 56, 57. Considering the influence of different permeabilities on frequency modulation, setting different permeability scenes: low permeability (19.73%), medium permeability (36.35%), high permeability (58.59%). Some of the parameters are shown in table 2.
TABLE 2 wind-power photovoltaic power generation system parameter table
Figure BDA0002242802670000171
(1) Wind power reactive voltage regulation capacity
Wind speed also has randomness due to randomness of wind power generation output power, so reactive power limits of the wind speed are different under different wind speeds. The reactive tap capacity limits at different permeabilities are shown in fig. 9-11. With the continuous increase of new energy permeability, the reactive limit range is also continuously increased: the low to medium permeability increases by about 108% and the medium to high permeability increases by about 140%. And the reactive limit range of the new energy source is continuously fluctuated due to the fluctuation of the output of the new energy source, and the reactive limit range of the wind power generation is reduced and is not symmetrical along with the increase of the wind power generation power, which is a result of the operation mode of the wind power generation system. Meanwhile, wind power generation can be realized in 24 hours all day, so that the wind power generation system has the advantages of wide reactive power regulation range and large regulation time period, but has the defect of complex operation control of a fan.
(2) Photovoltaic reactive voltage regulation capacity
The photovoltaic output power is different from the wind driven generator in reactive voltage regulation capacity due to different illumination characteristics, the photovoltaic reactive voltage regulation capacity limit under different permeability is shown in fig. 12 to 14, and it can be known from the graph that relative to the wind power voltage regulation capacity, the photovoltaic voltage regulation reactive limit range is continuously increased along with the increase of the permeability of new energy, and only 6 to 19 times of the new energy have the reactive voltage regulation capacity, which is caused by the photovoltaic output characteristics. But compare in the complicated control mode of wind-powered electricity generation, the cost of photovoltaic voltage regulation is little, and application scope is wide, consequently need add photovoltaic and wind-powered electricity generation and carry out voltage regulation capacity standby simultaneously in electric power system, improvement electric power system's that can be better stability.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims (8)

1. A method for evaluating the frequency modulation and voltage regulation capacity of a large-scale new energy participating receiving-end power grid is characterized by comprising the following steps: the method comprises the following steps:
the wind speed is divided into intervals according to wind speed samples of each wind power plant, and the wind power plant frequency modulation capacity is evaluated through a wind power generation frequency modulation capacity evaluation model;
evaluating the frequency modulation capacity of the photovoltaic power generation system by the photovoltaic power generation frequency modulation capacity evaluation model through the illumination intensity sample of the photovoltaic power station;
calculating an equivalent inertia time constant of the power system;
evaluating the voltage regulating capacity of the wind power plant through a wind power generation voltage regulating capacity evaluation model;
evaluating the voltage regulating capacity of the photovoltaic power station through a photovoltaic power generation voltage regulating capacity evaluation model;
the wind speed samples of the wind power plants and the illumination intensity samples of the photovoltaic power stations are generated by adopting a Gaussian mixture model to construct a probability distribution model of wind speed and illumination intensity according to historical wind speed and illumination intensity data of the wind power plants and the photovoltaic power stations; the new energy generator is controlled by adopting a virtual synchronous generator technology.
2. The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid according to claim 1 is characterized in that: the Gaussian mixture model is used for constructing a probability distribution model of wind speed and illumination intensity:
Figure FDA0002242802660000011
in the formula (I), the compound is shown in the specification,
Figure FDA0002242802660000012
is the probability distribution of the kth part; omegakA weight of a kth part of a Gaussian mixture function; mu.skAnd σkRespectively, the expected and standard deviation of the kth part; n is a radical oftFor the number of components to fit, k is 1,2 … NtX is a random variable, Φ is the illumination intensity or the wind speed, wherein the weight satisfies the following constraint:
Figure FDA0002242802660000013
3. the method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid according to claim 1 is characterized in that: the wind power plant frequency modulation capacity evaluation method comprises the following steps of carrying out interval division on wind speed through wind speed samples of each wind power plant, and evaluating the frequency modulation capacity of the wind power plant through a wind power generation frequency modulation capacity evaluation model, wherein the method specifically comprises the following steps:
the wind speed is divided into four sections: the method comprises the following steps of low wind speed, medium wind speed and high wind speed, and is specifically divided into:
Figure FDA0002242802660000014
under the lower wind speed section i ═ 1, adopt the simulation inertia control mode, can be used for increasing the kinetic energy of electric power output for a short time with fan rotating part storage and convert into fan frequency modulation power:
Figure FDA0002242802660000021
in the formula, PijThe frequency modulation capacity of a jth fan under the ith wind speed type is J, and the J is the rotational inertia of a rotating part of the fan; omegaAThe rotating speed of the fan when the fan participates in the frequency modulation starting is set; omegaMPPTThe rotating speed of the fan when the fan outputs the maximum power is shown as η, the conversion efficiency from kinetic energy to electric energy is shown as i, the wind speed types of the fan are lower speed, middle speed and high speed 3, and j is the serial number of the fan under the wind speed i type;
and (3) under the medium wind speed section, i is 2, the optimal fan load reduction driving point is obtained by combining the simulation inertia control and the overspeed control, and the frequency modulation capacity of the fan at the moment is as follows:
Figure FDA0002242802660000022
in the formula, PMPPTMaximum power, omega, output by the fanrIs the rotational speed, P, of the fan rotorbThe expression is shown as the following formula:
Figure FDA0002242802660000023
in the formula, kbA coefficient which represents that the output power of the fan and the rotating speed of the rotor are approximately 3 times;
when the high wind speed section i is equal to 3, adopting pitch angle control, wherein the frequency modulation capacity of the fan at the moment is as follows:
Pij＝Pm max-Pm min(7)
wherein, Pm maxThe maximum aerodynamic power which can be captured by the fan is represented, and the calculation method is shown as the following formula:
Figure FDA0002242802660000024
in the formula, Cp maxRepresenting the maximum power coefficient of the fan; λ represents tip speed ratio, λ ═ ω R1/vijOmega is the angular velocity of the fan blade, R1Representing fan sweep radius, vijThe speed of a fan blade of a jth fan under the ith wind speed type is β, the rho is the air density, A represents the swept area of the fan blade;
Pm minthe minimum aerodynamic power captured by the fan is represented, and the calculation method is as follows:
Figure FDA0002242802660000025
in the formula, Cp minRepresenting a minimum power coefficient of the fan;
obtaining the total frequency modulation capacity of the wind power plant:
Figure FDA0002242802660000031
Figure FDA0002242802660000032
in the formula, PfRepresenting the total frequency modulation capacity of the wind power place; n represents the number of fans in the wind farm; i denotes the type of wind speed of the fan, NRIndicating the total number of fans in the ith interval, ξijIs the probability that the jth fan is in the i-type wind speed interval, pijRepresenting the frequency modulation capacity of the jth fan in the i-type wind speed interval.
4. The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid according to claim 1 is characterized in that: through photovoltaic power plant illumination intensity sample, photovoltaic power generation frequency modulation capacity evaluation model evaluates the frequency modulation capacity of photovoltaic power generation system, specifically:
when the voltage of the photovoltaic array is U, the current of the maximum power point of the corresponding photovoltaic array is I:
Figure FDA0002242802660000033
wherein: i isscFor short-circuit current of photovoltaic array, VocFor photovoltaic array open circuit voltage, Im,VmRespectively the maximum power point current and the voltage of the photovoltaic array,
C2＝(Vm/Voc-1)/ln(1-Im/Isc) (14)
when considering the effect of the change in solar radiation,
Figure FDA0002242802660000035
wherein the content of the first and second substances,
DI＝(R/Rref-1)·Isc(16)
DV＝-Rs·DI (17)
wherein R is the luminous intensity, RrefAs reference value of solar radiation, RsIs the series resistance of the photovoltaic module;
the power of the photovoltaic array at any solar radiation intensity is:
Figure FDA0002242802660000036
when the MPPT point is controlled to operate at the maximum power, dP/dU is equal to 0, and the voltage U of the maximum power point of the photovoltaic array is obtainedmaxMaximum power P of photovoltaic arrayMPPTThe following equation is obtained:
PMPPT＝Imax·Umax(19)
Imaxa current that is the maximum power point of the photovoltaic array;
the frequency modulation capacity of the photovoltaic is expressed as:
in the formula, PgThe method comprises the following steps of (1) establishing a photovoltaic power generation frequency modulation capacity evaluation model for photovoltaic frequency modulation capacity, wherein epsilon is the percentage of the frequency modulation capacity to the maximum output power; pl MPPTRepresents the maximum power of the ith photovoltaic array, NlFor the number of photovoltaic arrays, l 1,2l。
5. The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid according to claim 1 is characterized in that: calculating an equivalent inertia time constant of the power system, specifically:
the inertia constant H of the synchronous generator is shown as follows:
Figure FDA0002242802660000042
in the formula, WkThe kinetic energy is the rotational kinetic energy of the new energy generator at the rated rotating speed; sNRated capacity of the new energy generator; j is the rotor moment of inertia, Ω0Synchronizing the angular velocity for the generator;
in a short time, the calculation formula of the equivalent inertia time constant is as follows:
Figure FDA0002242802660000043
in the formula, Hi1And Si1Are respectively a unit i1Inertia time constant and capacity of i1＝1,2,...,m+nIncluding synchronous generators and new energy machines participating in a primary frequency responseGroup, n, m respectively represent the number of synchronous generators and new energy generators, SN,sRepresents the total capacity of the generator to generate power;
virtual inertia time constant H of equivalent synchronous generator of power systemeqThe solution is solved by the following formula:
Figure FDA0002242802660000051
in the formula, Hsi2Is the inertia time constant, i, of the synchronous generator i22＝1,2,...,n；Hw-eqj2An inertia time constant of the new energy generator j2, j2 ═ 1, 2.. multidot.m;
Figure FDA0002242802660000057
rated capacity of synchronous generator i 2; sNwj2Is the rated capacity of the new energy generator j 2.
6. The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid according to claim 1 is characterized in that: the wind power plant voltage regulation capacity is evaluated through a wind power generation voltage regulation capacity evaluation model, and the method specifically comprises the following steps:
will be 0 to [ V ]0]+1 equal division by k1A region, [ V ]0]Is less than the natural wind speed V0Is selected as the maximum integer of k1＝[V0]+1；
Natural wind speed is V0In the interval (i)v-1,iv]The ratio P of the inner generator to the total generatorivComprises the following steps:
Figure FDA0002242802660000052
iv＝1,2,…,k1；NAthe total number of wind driven generators;
and (3) solving the upper and lower reactive power limits of the wind driven generator after the wind speed is known:
Figure FDA0002242802660000053
in the formula, nivIs the interval (i)v-1,iv]Number of fans, PsActive power of the wind driven generator; qmaxAnd QminThe upper limit and the lower limit of the reactive power regulation of the wind driven generator are respectively set; u shapesIs the stator voltage peak value of the wind driven generator; xsIs the stator reactance of the wind driven generator; xmIs the excitation reactance of the wind driven generator; i isr maxIs the maximum value of the current on the rotor side; q0The internal reactive power consumption of the power system is realized;
at a natural wind speed of V0And the upper and lower boundaries of the overall reactive power regulation range of the wind power plant are as follows:
Figure FDA0002242802660000054
in the formula (I), the compound is shown in the specification,and
Figure FDA0002242802660000056
the upper and lower boundaries are respectively the total wind power reactive power regulation of the wind power plant; k is a radical oflIs the reactive loss coefficient; m is1The total number of fans; p is a radical ofivFor a natural wind speed V0Lower wind speed interval (i)v-1,iv]The proportion of the inner fans to the total number of the fans,
Figure FDA0002242802660000061
respectively represent the ithvAnd the upper limit and the lower limit of the interval wind driven generator are adjusted in a reactive mode.
7. The method for evaluating the frequency modulation and voltage regulation capacity of the large-scale new energy participating receiving-end power grid according to claim 1 is characterized in that: the photovoltaic power station voltage regulation capacity is evaluated through the photovoltaic power generation voltage regulation capacity evaluation model, and the method specifically comprises the following steps:
the illumination intensity of each photovoltaic power generation system is known, and the illumination intensity is known for solar photovoltaicFor the power generation system, assuming that a solar array has M modules, each module has an area S, a photoelectric conversion efficiency γ, and R is the illumination intensity, the active power output P of the solar photovoltaic isrComprises the following steps:
Pr＝R·M·S·γ (26)
the maximum reactive power regulation range of the photovoltaic generator is obtained through the relation of active power, reactive power and power factor:
Figure FDA0002242802660000062
in the formula (I), the compound is shown in the specification,
Figure FDA0002242802660000063
the upper and lower boundaries of the q-th photovoltaic array reactive power regulation are respectively,
Figure FDA0002242802660000064
is the maximum adjustable power factor; q0The reactive power required to be consumed by the photovoltaic power generation system is represented;
for N1Photovoltaic generator set, the maximum reactive power control range can be expressed as:
Figure FDA0002242802660000065
in the formula (I), the compound is shown in the specification,
Figure FDA0002242802660000066
and
Figure FDA0002242802660000067
the upper and lower boundaries of the reactive power regulation of the photovoltaic power generation system are q ═ 1,2, …, N1。
8. A large-scale new energy participation receiving end power grid frequency modulation and voltage regulation capability assessment system is characterized in that: the method comprises the following steps:
the wind power plant frequency modulation capacity evaluation module is used for carrying out interval division on the wind speed through wind speed samples of each wind power plant and evaluating the frequency modulation capacity of the wind power plant through a wind power generation frequency modulation capacity evaluation model;
the photovoltaic power generation frequency modulation capacity evaluation module is used for evaluating the frequency modulation capacity of the photovoltaic power generation system through the photovoltaic power station illumination intensity sample and the photovoltaic power generation frequency modulation capacity evaluation model;
the equivalent inertia time constant calculation module is used for calculating an equivalent inertia time constant of the power system;
the wind power plant voltage regulation capacity evaluation module is used for evaluating the voltage regulation capacity of the wind power plant through the wind power generation voltage regulation capacity evaluation model;
the photovoltaic power station voltage regulation capacity evaluation module is used for evaluating the voltage regulation capacity of the photovoltaic power station through the photovoltaic power generation voltage regulation capacity evaluation model;
the wind speed samples of the wind power plants and the illumination intensity samples of the photovoltaic power stations are generated by adopting a Gaussian mixture model to construct a probability distribution model of wind speed and illumination intensity according to historical wind speed and illumination intensity data of the wind power plants and the photovoltaic power stations; the new energy generator is controlled by adopting a virtual synchronous generator technology.
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CN113283093A (en) * 2021-05-31 2021-08-20 国网内蒙古东部电力有限公司 Evaluation method based on new energy power generation grid-connected coordination cost
CN113326996A (en) * 2020-12-10 2021-08-31 国网山东省电力公司德州供电公司 Safety risk assessment method for power grid in high-proportion new energy access region
CN113541171A (en) * 2021-06-22 2021-10-22 国网湖南省电力有限公司 Control method and system for unified scheduling of large-scale energy storage power station

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CN113078659A (en) * 2021-03-31 2021-07-06 西安热工研究院有限公司 Capacity selection method for AGC frequency modulation device of energy storage auxiliary thermal power generating unit
CN113283093A (en) * 2021-05-31 2021-08-20 国网内蒙古东部电力有限公司 Evaluation method based on new energy power generation grid-connected coordination cost
CN113541171A (en) * 2021-06-22 2021-10-22 国网湖南省电力有限公司 Control method and system for unified scheduling of large-scale energy storage power station
CN113541171B (en) * 2021-06-22 2022-10-28 国网湖南省电力有限公司 Control method and system for unified scheduling of large-scale energy storage power stations

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