CN116579191A

CN116579191A - Load model modeling method and system considering electrochemical energy storage equipment

Info

Publication number: CN116579191A
Application number: CN202310863495.XA
Authority: CN
Inventors: 王�琦; 牟佳男; 孙华东; 赵兵; 兰天楷; 贺静波; 李建华; 郭强; 郑志伟; 裘微江
Original assignee: China Electric Power Research Institute Co Ltd CEPRI
Current assignee: China Electric Power Research Institute Co Ltd CEPRI
Priority date: 2023-07-14
Filing date: 2023-07-14
Publication date: 2023-08-11

Abstract

The invention provides a load model modeling method and a system considering electrochemical energy storage equipment, wherein the method aims at a comprehensive load model of electric power system simulation, adds an equivalent electrochemical energy storage module to equivalent-simulate a plurality of electrochemical energy storage equipment in a power distribution area provided by a transformer substation, further provides a method for determining equivalent electrochemical energy storage module model parameters based on statistics and synthesis on the basis, realizes accurate simulation of comprehensive load characteristics of a power distribution network containing the electrochemical energy storage equipment, overcomes the defect that the traditional dynamic load model cannot describe the influence of the electrochemical energy storage equipment on the power grid characteristics, can be widely applied to load modeling software containing the electrochemical energy storage equipment, and can be comprehensively applied to calculation and planning design of a power grid mode, so that the accuracy of power grid simulation calculation is improved, and more accurate simulation analysis results are provided for power grid analysis decisions.

Description

Load model modeling method and system considering electrochemical energy storage equipment

Technical Field

The invention relates to the field of power simulation, and in particular relates to a load model modeling method and system considering electrochemical energy storage equipment.

Background

In recent years, with the rapid development of new energy technology, the form of an electric power system is greatly changed, and the development of green low-carbon energy is a trend of the future energy and electric power industry. The high-proportion new energy access becomes the basic characteristic and development form of a novel power system. Under the background, a large amount of distributed new energy units (wind power, photovoltaic and the like) continuously permeate into the power distribution network, new energy power generation gradually shows the characteristic of dispersion, the topological structure of the power distribution network is changed, and the power distribution network shows a new form. In sharp contrast to the new energy developed at high speed at present, the access of the high-proportion random and fluctuation new energy unit provides new challenges for the safe, stable, flexible and economic operation of the power distribution system. As a key technology of a novel power system, an energy storage technology is considered as an important means for solving the problem of unstable new energy output. The combined operation of energy storage and new energy power generation is a development trend of a novel power distribution network.

From the aspect of conversion and storage, the energy storage elements can be divided into four categories, namely physical energy storage, phase change energy storage, electrochemical energy storage and electromagnetic energy storage. Electrochemical energy storage is widely applied to a power grid with the advantages of large capacity, high energy efficiency, flexible capacity configuration and the like. In practice, the duty ratio of the electrochemical energy storage device in the load area is larger and larger, and the fault ride through characteristic of the electrochemical energy storage device has a great influence on the safety and stability characteristics of the alternating current power grid, so that research and consideration on a load modeling method of the electrochemical energy storage device are needed. However, for the situation that the transformer substation is provided with a plurality of electrochemical energy storage devices, if a load model is built to perform simulation calculation on a large power grid of the power system, each electrochemical energy storage device is modeled in detail, so that the number of simulation nodes is far beyond the calculation capability of a simulation platform, and simulation cannot be performed.

Disclosure of Invention

In order to solve the technical problems that in the prior art, the duty ratio of electrochemical energy storage equipment in a load area is larger and larger, but when load modeling of fault crossing is considered, if each electrochemical energy storage equipment is modeled in detail, the number of simulation nodes is far beyond the calculation capability of a simulation platform, and simulation cannot be performed, the invention provides a load model modeling method and system considering the electrochemical energy storage equipment.

According to an aspect of the present invention, there is provided a load model modeling method considering an electrochemical energy storage device, the method comprising:

for a transformer substation with M electrochemical energy storage devices in a power distribution area, establishing a comprehensive load model of the transformer substation, wherein the comprehensive load model comprises power distribution network equivalent impedance and reactive compensation, and equivalent load modules respectively established for different types of loads in the power distribution area of the transformer substation, wherein the equivalent load modules comprise equivalent electrochemical energy storage modules established for the M electrochemical energy storage devices;

acquiring the active power, reactive power, bus voltage and impedance of a transmitting end of a transformer/distribution line in a power distribution area of the transformer substation and the load current of all loads in the power distribution area of the transformer substation;

Calculating equivalent impedance parameter values of the power distribution network according to the active power, reactive power, bus voltage and impedance of the power transmission end of the transformer/power distribution line and the load current;

acquiring rated capacity, active power, reactive power, machine end voltage, active current, reactive current and active current ride-through control strategies of M electrochemical energy storage devices, and bus voltage at a high-voltage side of a main transformer of the transformer substation, wherein the active power and the reactive power are obtained;

calculating equivalent rated capacity, equivalent active power and equivalent reactive power of the equivalent electrochemical energy storage module according to the rated capacity, active power and reactive power of the M electrochemical energy storage devices;

calculating equivalent control parameter values during low voltage ride through of the equivalent electrochemical energy storage modules according to active power, reactive power, machine end voltage and active current of the M electrochemical energy storage devices and bus voltage at the high voltage side of the main transformer of the transformer substation;

calculating equivalent control parameter values of the low-voltage ride through recovery starting points of the equivalent electrochemical energy storage modules according to the active currents and the reactive currents of the M electrochemical energy storage devices;

Calculating equivalent control parameter values of the low voltage ride through recovery stage of the equivalent electrochemical energy storage modules according to active current ride through control strategies of the M electrochemical energy storage devices and the active current and rated capacity;

and determining a comprehensive load model of the transformer substation according to the equivalent impedance parameter value of the power distribution network, the equivalent rated capacity, the equivalent active power and the equivalent reactive power of the equivalent electrochemical energy storage module, the equivalent control parameter value during low voltage ride through, the equivalent control parameter value of the low voltage ride through recovery starting point, the equivalent control parameter value of the low voltage ride through recovery stage and the parameter values of other equivalent load modules except the equivalent electrochemical energy storage module.

According to another aspect of the present invention, there is provided a load model modeling system considering an electrochemical energy storage device, the system comprising:

the system comprises a model building module, a model analysis module and a model analysis module, wherein the model building module is used for building a comprehensive load model of a transformer substation with M electrochemical energy storage devices in a power distribution area, wherein the comprehensive load model comprises power distribution network equivalent impedance and reactive compensation, and equivalent load modules respectively built for different types of loads in the power distribution area of the transformer substation, and the equivalent load modules comprise equivalent electrochemical energy storage modules built for the M electrochemical energy storage devices;

A first data module, configured to obtain active power, reactive power, bus voltage and impedance of a transmitting end of a transformer/distribution line in a power distribution area of the substation, and load currents of all loads in the power distribution area of the substation;

the first calculation module is used for calculating equivalent impedance parameter values of the power distribution network according to the active power, the reactive power, the bus voltage and the impedance of the power transmission end of the transformer/distribution line and the load current;

the second data module is used for acquiring rated capacity, active power, reactive power, machine end voltage, active current, reactive current and active current ride-through control strategies of the M electrochemical energy storage devices, and bus voltage, active power and reactive power of the high-voltage side of the main transformer of the transformer substation;

the second calculation module is used for calculating the equivalent rated capacity, equivalent active power and equivalent reactive power of the equivalent electrochemical energy storage module according to the rated capacity, active power and reactive power of the M electrochemical energy storage devices;

the third calculation module is used for calculating equivalent control parameter values during low voltage ride through of the equivalent electrochemical energy storage module according to the active power, reactive power, machine end voltage and active current of the M electrochemical energy storage devices and bus voltage at the high voltage side of the main transformer of the transformer substation;

The fourth calculation module is used for calculating an equivalent control parameter value of the low voltage ride through recovery starting point moment of the equivalent electrochemical energy storage module according to the active currents and the reactive currents of the M electrochemical energy storage devices;

the fifth calculation module is used for calculating an equivalent control parameter value of the low voltage ride through recovery stage of the equivalent electrochemical energy storage module according to the active current ride through control strategies of the M electrochemical energy storage devices and the active current and rated capacity;

the model determining module is used for determining the comprehensive load model of the transformer substation according to the equivalent rated capacity, the equivalent active power and the equivalent reactive power of the equivalent electrochemical energy storage module, the equivalent control parameter value during low voltage ride through, the equivalent control parameter value of the low voltage ride through recovery starting point and the equivalent control parameter value of the low voltage ride through recovery stage, and the parameter values of other equivalent load modules except the equivalent electrochemical energy storage module.

According to the load model modeling method and system considering the electrochemical energy storage equipment, the method aims at a comprehensive load model of power system simulation, the equivalent electrochemical energy storage modules are added to equivalently simulate a plurality of electrochemical energy storage characteristics in a power distribution area provided by a transformer substation, further, a method for determining equivalent electrochemical energy storage module model parameters based on statistics synthesis is provided on the basis, the comprehensive load characteristics of a power distribution network containing electrochemical energy storage are accurately simulated, the defect that the traditional dynamic load model cannot describe the influence of the electrochemical energy storage on the power grid characteristics is overcome, the load model can be widely applied to load modeling software containing the electrochemical energy storage power station, the generated load model parameters containing the electrochemical energy storage power station can be comprehensively applied to calculation and planning design of a power grid mode, the accuracy of power grid simulation calculation is improved, and more accurate simulation analysis results are provided for power grid analysis decisions.

Drawings

Exemplary embodiments of the present invention may be more completely understood in consideration of the following drawings:

FIG. 1 is a flow chart of a load model modeling method that considers an electrochemical energy storage device in accordance with a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of a composite load model that considers an electrochemical energy storage device in accordance with a preferred embodiment of the present invention;

fig. 3 is a schematic structural view of a load model modeling system considering an electrochemical energy storage device according to a preferred embodiment of the present invention.

Detailed Description

The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the examples described herein, which are provided to fully and completely disclose the present invention and fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like elements/components are referred to by like reference numerals.

Unless otherwise indicated, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, it will be understood that terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.

Exemplary method

Fig. 1 is a flowchart of a load model modeling method considering an electrochemical energy storage device according to a preferred embodiment of the present invention. As shown in fig. 1, the load model modeling method that considers an electrochemical energy storage device according to the preferred embodiment begins with step 101.

In step 101, for a substation in a supplied and distributed area comprising M electrochemical energy storage devices, a comprehensive load model of the substation is established, wherein the comprehensive load model comprises a distribution network equivalent impedance and reactive compensation, and equivalent load modules respectively established for different types of loads in the supplied and distributed area of the substation, and the equivalent load modules comprise equivalent electrochemical energy storage modules established for the M electrochemical energy storage devices.

Fig. 2 is a schematic structural view of a load model considering an electrochemical energy storage device according to a preferred embodiment of the present invention. As shown in fig. 2, in the preferred embodiment, the comprehensive load model including the electrochemical energy storage device is divided into 6 main parts, which are respectively equal-value impedance of the power distribution network, equal-value electrochemical energy storage module, equal-value distributed new energy power generation module, equal-value static load, equal-value motor module and reactive compensation. The equivalent distributed new energy power generation module comprises an equivalent direct-driven fan module, an equivalent doubly-fed fan module and an equivalent photovoltaic power generation module, wherein an equivalent static load comprises a constant impedance load, a constant current load and a constant power load, and an equivalent motor comprises an equivalent induction motor and an equivalent same-frequency engine. For the equivalent static load, the equivalent distributed new energy power generation module, the equivalent motor and the equivalent parameter calculation method of reactive compensation, the prior art is already described or other patents are additionally described, and the description is omitted here.

At step 102, the power supply end active power, reactive power, bus voltage and impedance of the transformer/distribution line in the supplied distribution area of the substation, and the load current of all loads in the supplied distribution area of the substation are obtained.

In step 103, the equivalent impedance parameter value of the distribution network is calculated according to the active power, the reactive power, the bus voltage and the impedance of the transmitting end of the transformer/distribution line and the load current.

Preferably, the calculating the equivalent impedance parameter value of the power distribution network according to the active power, the reactive power, the bus voltage and the impedance of the transmitting end of the transformer/distribution line and the load current, wherein the calculating formula of the equivalent impedance of the power distribution network is as follows:

wherein R is _D And X _D Respectively representing equivalent resistance and reactance of a power distribution network in a power distribution area provided by the transformer substation; p (P) _j And Q _j Active power and reactive power at the power transmitting end of a jth transformer/distribution line respectively representing power distribution areas provided by the transformer substation, U _j A j-th transformer/distribution line power transmission end bus voltage amplitude value Ž representing power distribution area provided by the transformer substation _j A j-th transformer/distribution line impedance representing a power distribution area provided by the substation; i _Li Load current representing the ith load of the distribution area provided by the transformer substation, wherein 1.ltoreq.j.ltoreq.l，1≤i≤k。

In the preferred embodiment, the transformers and distribution lines of the distribution substation are numbered in unison.

In step 104, the rated capacity, active power, reactive power, terminal voltage, active current, reactive current and active current ride-through control strategy of the M electrochemical energy storage devices, and bus voltage, active power and reactive power of the high-voltage side of the main transformer of the substation are obtained.

In step 105, the equivalent rated capacity, the equivalent active power and the equivalent reactive power of the equivalent electrochemical energy storage module are calculated according to the rated capacities of the M electrochemical energy storage devices.

Preferably, the calculating the equivalent rated capacity, equivalent active power and equivalent reactive power of the equivalent electrochemical energy storage module according to the rated capacities, active power and reactive power of the M electrochemical energy storage devices includes:

calculating equivalent rated capacity S of the equivalent electrochemical energy storage module according to the rated capacities of the M electrochemical energy storage devices _{N_EQ} The calculation formula is as follows:

wherein S is _{N_i} The rated capacity of the ith electrochemical energy storage device in the power distribution area provided by the transformer substation is set, and M is the total number of electrochemical energy storage devices in the power distribution area provided by the transformer substation;

Calculating the maximum active power P of the equivalent electrochemical energy storage module according to the maximum active power of the M electrochemical energy storage devices _max,EQ The calculation formula is as follows:

wherein P is _{max_i} Is the maximum active power of the ith electrochemical energy storage device in the power distribution area provided by the transformer substation;

according to the M electrochemical energy storageMaximum reactive power Q of equivalent electrochemical energy storage module is calculated to maximum reactive power of equipment _{max_EQ} The calculation formula is as follows:

in which Q _{max_i} The maximum reactive power of the ith electrochemical energy storage device in the power distribution area provided by the transformer substation;

calculating the actual active power P of the equivalent electrochemical energy storage module according to the actual active powers of the M electrochemical energy storage devices _EQ The calculation formula is as follows:

wherein P is _i Is the actual active power of the ith electrochemical energy storage device in the power distribution area provided by the transformer substation;

calculating the actual reactive power Q of the equivalent electrochemical energy storage module according to the actual reactive power of the M electrochemical energy storage devices _EQ The calculation formula is as follows:

in which Q _i Is the actual reactive power of the ith electrochemical energy storage device of the power distribution area provided by the substation.

In step 106, the equivalent control parameter value during the low voltage ride through of the equivalent electrochemical energy storage module is calculated according to the active power, the reactive power, the machine end voltage and the active current of the M electrochemical energy storage devices, and the bus voltage at the high voltage side of the main transformer of the substation.

Preferably, the calculating the equivalent control parameter value during the low voltage ride through of the equivalent electrochemical energy storage module according to the active power, the reactive power, the terminal voltage and the active current of the M electrochemical energy storage devices and the bus voltage of the transformer substation includes:

establishing an active power control formula and a reactive power control formula during low voltage ride through of the equivalent electrochemical energy storage module, wherein the formulas are respectively as follows:

wherein P is _{LVRT_EQ} And Q _{LVRT_EQ} Active power and reactive power respectively equal to low voltage ride through time of electrochemical energy storage module, K _{P_LVRT_EQ} And P _{set_LV_EQ} A first equivalent active power control coefficient and a second equivalent active power control coefficient, K, respectively, during low voltage ride through of the equivalent electrochemical energy storage module _{Q_LVRT_EQ_f} And Q _{set_LV_EQ_f} The first equivalent reactive power control coefficient and the second equivalent reactive power control coefficient are corrected during the low voltage ride through period of the equivalent electrochemical energy storage module respectively, P _{0_EQ} And Q _{0_EQ} Respectively the initial active power and the initial reactive power of the equivalent electrochemical energy storage module in the low voltage ride through period;

adding the active power curves of the M electrochemical energy storage devices to obtain a sum curve of the active powers of the M electrochemical energy storage devices, recording the time when the sum of the active powers is maximum as t2, and obtaining the active power value P of the ith electrochemical energy storage device at the time t2 _i,t2 ；

According to the terminal voltages of the M electrochemical energy storage devices, the bus voltage at the high-voltage side of the main transformer of the transformer substation, the active power and the reactive power calculate a second equivalent active power control coefficient P _{set_LV_EQ} The calculation formula is as follows:

wherein V is _ti,t2 Is the terminal voltage of the ith electrochemical energy storage device at the moment T2, T _1i And T _2i The transformation ratio of the grid-connected transformer of the ith electrochemical energy storage device and the transformation ratio of the transformer with the high voltage level which is boosted after passing through the grid-connected transformer are respectively the high-voltage side per unit value/the low-voltage side per unit value of the corresponding transformer, and V _EQ,t2 Is the machine end voltage of the equivalent electrochemical energy storage module at the time t 2; p (P) _{set_LVi} Is the second active power control coefficient of the ith electrochemical energy storage device, U _1,t2 Is the bus voltage of the main transformer of the transformer substation at the time t2, P _1,t2 And Q _1,t2 Active power and reactive power flowing into the main transformer of the transformer substation at the time t2 respectively, wherein X is the equivalent reactance X of the distribution network _D A sum of high-voltage-side and medium-voltage-side reactance with the main transformer of the substation;

calculating initial active power P of the equivalent electrochemical energy storage module according to the initial active power of the M electrochemical energy storage devices _{0_EQ} The calculation formula is as follows:

wherein P is _{0_i} Is the initial active power of the ith electrochemical energy storage device in the power distribution area provided by the transformer substation;

According to the active power value P of the M electrochemical energy storage power stations _i,t2 The second equivalent active power control coefficient P _{set_LV_EQ} The initial active power P _{0_EQ} And the equivalent rated capacity S _{N_EQ} Calculating a first equivalent active power control coefficient K _{P_LVRT_EQ} The calculation formula is as follows:

wherein S is _b Is the system reference capacity;

adding the reactive power curves of the M electrochemical energy storage devices to obtain a sum curve of the reactive powers of the M electrochemical energy storage devices, recording the moment of maximum sum of the reactive powers as t4, and obtaining the reactive power value Q of the ith electrochemical energy storage device at the moment of t4 _i,t4 ；

According to the terminal voltages of the M electrochemical energy storage devices, the bus voltage at the high-voltage side of the main transformer of the transformer substation, active power and reactive power calculate an initial second equivalent reactive power control coefficient Q _{set_LV_EQ} The calculation formula is as follows:

wherein V is _ti,t4 Is the terminal voltage of the ith electrochemical energy storage device at the time t4, V _EQ,t4 Is the machine end voltage of the equivalent electrochemical energy storage module at the time t 4; u (U) _1,t4 Is the bus voltage of the main transformer of the transformer substation at the time t4, P _1,t4 And Q _1,t4 Active power and reactive power respectively flowing into the high-voltage side of the main transformer of the transformer substation at the time t4, Q _{set_LVi} Is a second reactive power control coefficient of the ith electrochemical energy storage device;

Calculating reactive power to be subtracted by the equivalent electrochemical energy storage module according to the active currents of the M electrochemical energy storage devices

Δq', the calculation formula of which is:

wherein I is _pi,t2 Is the active current of the ith electrochemical energy storage device at the moment t2, X _i Is the medium voltage between the ith electrochemical energy storage equipment grid-connected node and the main transformer of the power distribution stationReactance of the side node; in the actual topological structure of the transformer substation, the active current generates additional reactive power consumption on the line, and in the equivalent system, the reactive power consumption is less, so that the reactive power output of the electrochemical energy storage equipment is regulated and reduced to compensate the part with less reactive power consumption;

according to the initial second equivalent reactive power control coefficient Q _{set_LV_EQ} And calculating a corrected second equivalent reactive power control coefficient Q of the equivalent electrochemical energy storage module according to the reactive power delta Q' required to be regulated and reduced by the equivalent electrochemical energy storage module _{set_LV_EQ_f} The calculation formula is as follows:

calculating the initial reactive power Q of the equivalent electrochemical energy storage module according to the initial reactive power of the M electrochemical energy storage devices _{0_EQ} The calculation formula is as follows:

in which Q _{0_i} Is the initial reactive power of the ith electrochemical energy storage device in the power distribution area provided by the substation;

according to the reactive power value Q of the M electrochemical energy storage power stations _i,t4 The second equivalent reactive power control coefficient P is corrected _{set_LV_EQ_f} The initial reactive power Q _{0_EQ} And the equivalent rated capacity S _{N_EQ} Calculating and correcting a first equivalent reactive power control coefficient K _{Q_LVRT_EQ_f} The calculation formula is that

。

In the preferred embodiment, when the power grid is subjected to a large disturbance impact such as short circuit, in order to reduce the risk of over-current and off-grid of the inverter caused by low voltage, the electrochemical energy storage device has fault ride-through control, and the active and reactive characteristics during the low voltage ride-through period and the recovery process have a great influence on the stability characteristics of the power gridTherefore, when modeling the equivalent of the electrochemical energy storage device, it is necessary to perform the equivalent of the key dynamic parameters of the electrochemical energy storage device during the low voltage ride through, the low voltage ride through recovery starting point and the low voltage recovery process. Further, for the comprehensive load model shown in fig. 2, the grid-connected transformer of the electrochemical energy storage device is a low-voltage-class transformer, and the high-voltage-class transformer boosted by the grid-connected transformer is 110 kV. The main transformer of the power distribution station is 220kV/330kV, U _1,t2 And U _1,t4 The bus voltages of the transformer substation main transformer at the time t2 and the time t4 refer to the voltage values of the bus at the time t2 and the time t4 of 220kV/330kV side of the 220kV/330kV main transformer, and P _1,t2 And P _1,t4 Active power flowing into 220kV/330kV side of 220kV/330kV main transformer of transformer substation at time t2 and time t4 respectively, Q _1,t2 And Q _1,t4 Reactive power flowing into 220kV/330kV main transformer 220kV/330kV side of the transformer substation at the time t2 and the time t4 respectively.

In step 107, an equivalent control parameter value of the low voltage ride through recovery start point of the equivalent electrochemical energy storage module is calculated according to the active currents and the reactive currents of the M electrochemical energy storage devices.

Preferably, the calculating the equivalent control parameter value of the low voltage ride through recovery start point of the equivalent electrochemical energy storage module according to the active current and the reactive current of the M electrochemical energy storage devices includes:

according to the active control of the low voltage ride through recovery starting point time of the equivalent electrochemical energy storage module, an active power control formula and a reactive power control formula of the low voltage ride through recovery starting point time of the equivalent electrochemical energy storage module are respectively established according to an initial active current percentage control mode and a reactive current percentage control mode in a fault period, wherein the formulas are respectively as follows:

wherein I is _{PLVRECT0_EQ} And I _{QLVREC T0_EQ} Respectively equivalent active current and equivalent reactive current at low voltage ride through recovery start point time of equivalent electrochemical energy storage module, K _{PLVRECT0_EQ} The equivalent active current calculation coefficient is the equivalent active current calculation coefficient at the low-voltage ride through recovery starting point time of the equivalent electrochemical energy storage module; i _{P0_EQ} Is the initial equivalent active current per unit value of the equivalent electrochemical energy storage module, I _{QsetLVRECT0_EQ} Is a reactive power control parameter of the equivalent electrochemical energy storage module at the moment of the low voltage ride through recovery start;

calculating initial equivalent active current values I of equivalent electrochemical energy storage modules according to the initial active currents of the M electrochemical energy storage devices _{P0_EQ} The calculation formula is as follows:

wherein I is _P0i Is the initial active current of the ith electrochemical energy storage device;

calculating an equivalent active current value I of the low voltage ride through recovery starting point moment of the equivalent electrochemical energy storage module according to the active current values of the low voltage ride through recovery starting point moments of the M electrochemical energy storage devices _{PLVRECT0_EQ} The calculation formula is as follows:

wherein I is _PLVRECT0i Is equivalent active current at the moment of the low voltage ride through recovery start point of the ith electrochemical energy storage device;

according to the initial equivalent active current value I of the equivalent electrochemical energy storage module _{P0_EQ} And an equivalent active current value I at the start point of low voltage ride through recovery _{PLVRECT0_EQ} Equivalent active current calculation coefficient K at low voltage ride through recovery starting point time of equivalent electrochemical energy storage module _{PLVRECT0_EQ} The calculation formula is as follows:

Calculating an equivalent reactive current value I at the low voltage ride through recovery starting point time of the equivalent electrochemical energy storage module according to the reactive current values at the low voltage ride through recovery starting point time of the M electrochemical energy storage devices _{QLVRECT0_EQ} The calculation formula is as follows:

wherein I is _QLVRECT0i Is reactive current at the moment of starting the low-voltage ride through recovery of the ith electrochemical energy storage device;

according to the equivalent reactive current value I at the starting point of low-voltage ride through recovery of the equivalent electrochemical energy storage module _{QLVRECT0_EQ} Calculating reactive power control coefficient I of low-voltage ride through recovery starting point moment of equivalent electrochemical energy storage module _{QsetLVRECT0_EQ} The calculation formula is as follows:

。

in the preferred embodiment, no matter what control mode is used for recovering the starting point moment in the low voltage traversing period of the electrochemical energy storage equipment under the transformer substation, the equivalent electrochemical energy storage module adopts an active control mode according to the initial active current percentage and adopts a reactive current percentage control mode according to the fault period.

In step 108, according to the active current ride through control strategies of the M electrochemical energy storage devices, the active current and the rated capacity calculate the equivalent control parameter values of the equivalent electrochemical energy storage module in the low voltage ride through recovery stage.

Preferably, the calculating the equivalent control parameter value of the low voltage ride through recovery phase of the equivalent electrochemical energy storage module according to the active current ride through control strategy of the M electrochemical energy storage devices, the active current and the rated capacity includes:

when the active current ride through control strategy of the M electrochemical energy storage devices is a fixed slope recovery control mode, or the active current ride through control strategy of the M electrochemical energy storage devices includes a fixed slope recovery control mode and a recovery control mode according to an inertia curve, the equivalent electrochemical energy storage module establishes an active current control expression of a low voltage ride through recovery stage according to the fixed slope recovery control mode, where the expression is:

wherein I is _{PRECOVER_EQ} Is equivalent active current, delta T of the equivalent electrochemical energy storage module in the low voltage ride through recovery stage _EQ Is the recovery time, K, of the equivalent active current initial value before the failure recovered by the equivalent electrochemical energy storage module from the low voltage ride through recovery starting point moment _{IPRECOVER_EQ} Andrespectively calculating the equivalent active current calculation coefficient and the equivalent active rated current per unit value of the equivalent electrochemical energy storage module in the low voltage ride through recovery stage;

calculating the recovery time delta T of the equivalent electrochemical energy storage module from the low voltage ride through recovery starting point moment to the equivalent active current initial value before failure according to the initial active currents of the M electrochemical energy storage devices and the active currents at the low voltage ride through recovery starting point moment _EQ The calculation formula is as follows:

wherein max (DeltaT) ₁ ，ΔT ₂ ，…，ΔT _M ) Represent and take DeltaT ₁ ，ΔT ₂ ，…，ΔT _M Maximum value of DeltaT _i Is the recovery time, K, of the ith electrochemical energy storage device from the recovery start time to the initial value of the active current before the fault _IPRECOVERi Is the active current calculation coefficient of the low voltage ride through recovery stage preset by the ith electrochemical energy storage device,，P _Ni and U _Ni The active rated current per unit value, the rated power per unit value and the rated voltage per unit value of the ith electrochemical energy storage device are respectively;

calculating the equivalent active rated current per unit value of the low voltage ride through recovery stage of the equivalent electrochemical energy storage module according to the active rated current per unit values of the M electrochemical energy storage devicesThe calculation formula is as follows:

according to the equivalent active rated current per unit value of the equivalent electrochemical energy storage module in the low voltage ride through recovery stageRecovery time DeltaT _EQ Equivalent active current value I _{PLVRECT0_EQ} And equivalent active current initial value I _{P0_EQ} Calculating equivalent active current calculation coefficient K of equivalent electrochemical energy storage module in low voltage ride through recovery stage _{IPRECOVER_EQ} The calculation formula is as follows:

when the active current ride through control strategy of the M electrochemical energy storage devices is to recover the control mode according to the inertia curve, determining an inertia time constant T of the equivalent electrochemical energy storage module by the equivalent electrochemical energy storage module according to the inertia curve recovery control mode _EQ Calculation thereofThe formula is:

wherein S is _{N_i} And T _i The rated capacity of the ith electrochemical energy storage device in the power distribution area provided by the transformer substation and the inertia time constant of the low voltage ride through recovery stage are respectively S _{N_EQ} Is the equivalent rated capacity of the equivalent electrochemical energy storage module.

In step 109, according to the equivalent impedance parameter value of the power distribution network, the equivalent rated capacity, the equivalent active power and the equivalent reactive power of the equivalent electrochemical energy storage module, the equivalent control parameter value during the low voltage ride through, the equivalent control parameter value of the low voltage ride through recovery start point and the equivalent control parameter value of the low voltage ride through recovery stage, and the parameter values of other equivalent load modules except the equivalent electrochemical energy storage module, determining the comprehensive load model of the transformer substation.

According to the load model modeling method considering the electrochemical energy storage module, firstly, a comprehensive load model containing the equivalent electrochemical energy storage module is established, dynamic characteristics of a plurality of electrochemical energy storage devices in a power distribution area provided by a load station are subjected to equivalent simulation through the equivalent electrochemical energy storage module, further, a method for determining model parameters of the equivalent electrochemical energy storage module based on statistical synthesis is provided on the basis, so that comprehensive load dynamic characteristics of a power distribution network containing the electrochemical energy storage module are accurately simulated, the comprehensive load model is reasonable in structure and high in operability, can be widely applied to load modeling software containing the electrochemical energy storage device, and the generated load model parameters containing the electrochemical energy storage device can be comprehensively applied to power grid mode calculation, planning and design, so that accuracy of power grid simulation calculation is improved, and more accurate simulation analysis results are provided for power grid analysis decisions.

Exemplary System

Fig. 3 is a schematic structural view of a load model modeling system considering an electrochemical energy storage device according to a preferred embodiment of the present invention. As shown in fig. 3, the load model modeling system 300 of the present preferred embodiment, which considers an electrochemical energy storage device, includes:

the model building module 301 is configured to build, for a substation in which a power distribution area includes M electrochemical energy storage devices, a comprehensive load model of the substation, where the comprehensive load model includes equivalent impedance and reactive compensation of a power distribution network, and equivalent load modules respectively built for different types of loads in the power distribution area of the substation, where the equivalent load modules include equivalent electrochemical energy storage modules built for the M electrochemical energy storage devices;

a first data module 302, configured to obtain active power, reactive power, bus voltage and impedance of a transmitting end of a transformer/distribution line in a power distribution area of the substation, and load current of all loads in the power distribution area of the substation;

a first calculation module 303, configured to calculate an equivalent impedance parameter value of the power distribution network according to the active power, the reactive power, the bus voltage and the impedance of the power transmission end of the transformer/distribution line, and the load current;

The second data module 304 is configured to obtain rated capacities, active power, reactive power, machine side voltage, active current, reactive current and active current ride through control policies of the M electrochemical energy storage devices, and bus voltages at a high voltage side of the main transformer of the substation, active power and reactive power;

a second calculation module 305, configured to calculate an equivalent rated capacity, an equivalent active power and an equivalent reactive power of the equivalent electrochemical energy storage module according to the rated capacities of the M electrochemical energy storage devices;

a third calculation module 306, configured to calculate an equivalent control parameter value during low voltage ride through of the equivalent electrochemical energy storage module according to the active power, the reactive power, the machine side voltage and the active current of the M electrochemical energy storage devices, and the bus voltage on the high voltage side of the main transformer of the substation;

a fourth calculation module 307, configured to calculate an equivalent control parameter value of an equivalent electrochemical energy storage module at a low voltage ride through recovery start point according to active currents and reactive currents of the M electrochemical energy storage devices;

a fifth calculation module 308, configured to calculate an equivalent control parameter value of the low voltage ride through recovery stage of the equivalent electrochemical energy storage module according to the active current ride through control policies of the M electrochemical energy storage devices, the active current, and the rated capacity;

The model determining module 309 is configured to determine, according to the power distribution network equivalent impedance parameter value, the equivalent rated capacity, the equivalent active power and the equivalent reactive power of the equivalent electrochemical energy storage module, the equivalent control parameter value during the low voltage ride through, the equivalent control parameter value of the low voltage ride through recovery start point and the equivalent control parameter value of the low voltage ride through recovery stage, and the parameter values of other equivalent load modules except the equivalent electrochemical energy storage module, a comprehensive load model of the transformer substation.

Preferably, the first calculating module 303 calculates the equivalent impedance parameter value of the power distribution network according to the active power, the reactive power, the bus voltage and the impedance of the transmitting end of the transformer/distribution line, and the load current, wherein the calculation formula of the equivalent impedance of the power distribution network is:

wherein R is _D And X _D Respectively representing equivalent resistance and reactance of a power distribution network in a power distribution area provided by the transformer substation; p (P) _j And Q _j Active power and reactive power at the power transmitting end of a jth transformer/distribution line respectively representing power distribution areas provided by the transformer substation, U _j A j-th transformer/distribution line power transmission end bus voltage amplitude value Ž representing power distribution area provided by the transformer substation _j A j-th transformer/distribution line impedance representing a power distribution area provided by the substation; i _Li And the load current of the ith load of the power distribution area provided by the transformer substation is represented, wherein j is more than or equal to 1 and less than or equal to l, and i is more than or equal to 1 and less than or equal to k.

Preferably, the calculating, by the second calculating module 305, the calculating, by using the rated capacities of the M electrochemical energy storage devices, the equivalent rated capacities, the equivalent active power and the equivalent reactive power of the equivalent electrochemical energy storage modules includes:

calculating the maximum reactive power Q of the equivalent electrochemical energy storage module according to the maximum reactive power of the M electrochemical energy storage devices _{max_EQ} The calculation formula is as follows:

Preferably, the third calculation module 306 calculates an equivalent control parameter value during low voltage ride through of the equivalent electrochemical energy storage module according to the active power, reactive power, terminal voltage and active current of the M electrochemical energy storage devices, and the bus voltage of the substation, including:

Wherein P is _{LVRT_EQ} And Q _{LVRT_EQ} Active power and reactive power respectively equal to low voltage ride through time of electrochemical energy storage module, K _{P_LVRT_EQ} And P _{set_LV_EQ} A first equivalent active power control coefficient and a second equivalent active power control coefficient, K, respectively, during low voltage ride through of the equivalent electrochemical energy storage module _{Q_LVRT_EQ_f} And Q _{set_LV_EQ_f} The first equivalent reactive power control coefficient and the second equivalent reactive power control coefficient are respectively corrected during the low voltage ride through period of the equivalent electrochemical energy storage moduleEqual-value reactive power control coefficient, P _{0_EQ} And Q _{0_EQ} Respectively the initial active power and the initial reactive power of the equivalent electrochemical energy storage module in the low voltage ride through period;

wherein S is _b Is the system reference capacity;

Δq', the calculation formula of which is:

wherein I is _pi,t2 Is the active current of the ith electrochemical energy storage device at the moment t2, X _i The reactance from the ith electrochemical energy storage equipment grid-connected node to the medium-voltage side node of the main transformer of the power distribution station;

according to the M electricityReactive power value Q of chemical energy storage power station _i,t4 The second equivalent reactive power control coefficient P is corrected _{set_LV_EQ_f} The initial reactive power Q _{0_EQ} And the equivalent rated capacity S _{N_EQ} Calculating and correcting a first equivalent reactive power control coefficient K _{Q_LVRT_EQ_f} The calculation formula is as follows:

。

preferably, the fourth calculating module 307 calculates an equivalent control parameter value of the low voltage ride through recovery start point of the equivalent electrochemical energy storage module according to the active currents and the reactive currents of the M electrochemical energy storage devices, including:

calculation of initial active current from the M electrochemical energy storage devicesInitial equivalent active current value I of equivalent electrochemical energy storage module _{P0_EQ} The calculation formula is as follows:

。

preferably, the fifth calculating module 309 calculates an equivalent control parameter value of the low voltage ride through recovery phase of the equivalent electrochemical energy storage module according to the active current ride through control strategy of the M electrochemical energy storage devices, the active current, and the rated capacity, including:

calculating equivalent electrochemical according to the initial active currents of the M electrochemical energy storage devices, the active currents at the moment of starting the low-voltage ride through recovery and the active rated currentsRecovery time delta T of equivalent active current initial value before failure recovered by the energy storage module from low voltage ride through recovery starting point moment _EQ The calculation formula is as follows:

calculating the equivalent active rated current per unit value of the low voltage ride through recovery stage of the equivalent electrochemical energy storage module according to the active rated current per unit values of the M electrochemical energy storage devicesThe calculation formula is as follows: />

when the active current ride through control strategy of the M electrochemical energy storage devices is to recover the control mode according to the inertia curve, determining an inertia time constant T of the equivalent electrochemical energy storage module by the equivalent electrochemical energy storage module according to the inertia curve recovery control mode _EQ The calculation formula is as follows:

The load model modeling system considering the electrochemical energy storage devices in the preferred embodiment establishes a comprehensive load model including the equivalent electrochemical energy storage modules for a transformer substation including a plurality of electrochemical energy storage devices, and calculates model parameter values of the equivalent electrochemical energy storage modules, so that the step of determining the comprehensive load model is the same as the step adopted by the load model modeling method considering the electrochemical energy storage devices in the invention, and the technical effects achieved are the same, and are not described herein again.

The invention has been described with reference to a few embodiments. However, as is well known to those skilled in the art, other embodiments than the above disclosed invention are equally possible within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a/an/the [ means, component, etc. ]" are to be interpreted openly as referring to at least one instance of said means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

It will be appreciated by those skilled in the art that 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 flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations 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.

Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.

Claims

1. A method of modeling a load model in consideration of an electrochemical energy storage device, the method comprising:

2. The method according to claim 1, wherein the calculating the distribution network equivalent impedance parameter value according to the transformer/distribution line transmission end active power, reactive power, bus voltage and impedance, and the load current, wherein the calculation formula of the distribution network equivalent impedance is:

3. The method of claim 1, wherein the calculating the equivalent rated capacity, equivalent active power and equivalent reactive power of the equivalent electrochemical energy storage module from the rated capacities of the M electrochemical energy storage devices comprises:

4. The method of claim 1, wherein the calculating the equivalent control parameter value during the low voltage ride through of the equivalent electrochemical energy storage module from the active power, reactive power, machine side voltage and active current of the M electrochemical energy storage devices, and the bus voltage of the substation, the active power and reactive power, comprises:

wherein V is _ti,t2 Is the terminal voltage of the ith electrochemical energy storage device at the moment T2, T _1i And T _2i The transformation ratio of the grid-connected transformer of the ith electrochemical energy storage device and the transformation ratio of the transformer with the high voltage level which is boosted after passing through the grid-connected transformer are respectively the high-voltage side per unit value/the low-voltage side per unit value of the corresponding transformer, and V _EQ,t2 Is the machine end voltage of the equivalent electrochemical energy storage module at the time t 2; p (P) _{set_LVi} Is the second active power control coefficient of the ith electrochemical energy storage device, U _1,t2 Is the bus voltage of the main transformer of the transformer substation at the moment t2, P _1,t2 And Q _1,t2 Active power and reactive power flowing into the main transformer of the transformer substation at the time t2 respectively, wherein X is the equivalent reactance X of the distribution network _D A sum of high-voltage-side and medium-voltage-side reactance with the main transformer of the substation;

wherein S is _b Is the system reference capacity;

Δq', the calculation formula of which is:

according to the reactive power value Q of the M electrochemical energy storage power stations _i,t4 The corrected second equivalent reactive power control coefficient Q _{set_LV_EQ_f} The initial reactive power Q _{0_EQ} And the equivalent rated capacity S _{N_EQ} Calculating and correcting a first equivalent reactive power control coefficient K _{Q_LVRT_EQ_f} The calculation formula is as follows:

wherein S is _b Is the system reference capacity.

5. The method of claim 1, wherein calculating the equivalent control parameter value for the instant of onset of low voltage ride through recovery of the equivalent electrochemical energy storage module from the active and reactive currents of the M electrochemical energy storage devices comprises:

according to the equivalent reactive current value I at the starting point of low-voltage ride through recovery of the equivalent electrochemical energy storage module _{QLVRECT0_EQ} Calculating the starting point moment of low-voltage ride through recovery of equivalent electrochemical energy storage moduleReactive control coefficient I of (2) _{QsetLVRECT0_EQ} The calculation formula is as follows:

wherein S is _b Is the system reference capacity.

6. The method of claim 5, wherein calculating the equivalent control parameter value for the equivalent electrochemical energy storage module low voltage ride through recovery phase according to the active current ride through control strategy, active current, and rated capacity of the M electrochemical energy storage devices comprises:

according to the initial active currents of the M electrochemical energy storage devices, the active currents and the active currents at the starting point time of the low voltage ride through recoveryCalculating recovery time delta T of equivalent active current initial value before failure from low voltage ride through recovery starting point moment by using equivalent electrochemical energy storage module through power rated current _EQ The calculation formula is as follows:

7. A load model modeling system that accounts for an electrochemical energy storage device, the system comprising: