Energy storage system configuration method, system, storage medium and device

Abstract

The present invention provides a method, system, storage medium and device for configuring an energy storage system. The method comprises: determining the configuration parameters of the energy storage system according to the parameters of the power system, including: determining the energy storage frequency modulation coefficient, active power and energy that the energy storage system needs to be configured with; the determination of the energy storage frequency modulation coefficient that the energy storage system needs to be configured with comprises: calculating the maximum power fluctuation frequency modulation coefficient, synchronous unit frequency modulation coefficient and transient attenuation frequency modulation coefficient of the power system; building an energy storage converter control strategy based on the energy storage system configuration parameters and known operating data. The energy storage system configuration method of the present invention reduces the over-limit range of the transient frequency of the power system and improves the controllability of the transient output of the energy storage system.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy grid-connected control, and in particular, relates to an energy storage system configuration method, system, storage medium and device. Background Art

[0002] As the proportion of renewable energy power generation continues to grow, unbalanced power in the power system becomes more frequent, causing increasingly prominent problems of inertia and insufficient frequency regulation capacity. Against this background, energy storage systems are expected to play a key role in supply-side reforms to cope with the active power fluctuations and frequency challenges brought about by the grid connection of renewable energy. Taking Hawaii and California in the United States as examples, these regions have established large-scale battery energy storage stations to improve the quality of power supply. With the rapid development of power electronics technology, energy storage devices can achieve flexible power output under the control of converters, thereby achieving precise regulation of grid frequency.

[0003] At present, the effectiveness and feasibility of energy storage in frequency support work at different time scales have been fully demonstrated. In order to meet the working requirements in different environments, relevant scholars have proposed a variety of control and improvement strategies for energy storage grid-connected converters, which are mainly summarized into two categories: virtual synchronous machine control and droop control. In addition, considering the economy and reliability of energy storage frequency regulation, some scholars have also taken the parameter configuration of energy storage systems as the research object.

[0004] However, the current research on energy storage systems and their control technologies still has the following difficulties:

[0005] First, the control method of the virtual synchronous machine is relatively complex and of high order, and the coupling effect between the control parameters is obvious; second, the traditional droop control can only establish a proportional input-output relationship. If multiple support requirements are considered at the same time, multiple input windows are required, which increases the complexity; third, the synchronization between the generator set and the energy storage system, and between the generator sets in the frequency support work of the system is poor, and the transient frequency of the system is easy to exceed the limit; fourth, the dispersion of dynamic frequency will cause the transient output of the energy storage system to be affected by the installation location, and the transient process controllability of the energy storage system under the traditional control scheme is poor. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method, system, storage medium and device for configuring an energy storage system. Based on the power system parameters, the energy storage system configuration parameters are determined, and an energy storage converter control strategy based on the attenuation function is established to control the energy storage output. This can realize automatic adjustment of the output power of the energy storage system, improve the system transient frequency over-limit situation, and improve the controllability of the transient output of the energy storage system.

[0007] The present invention is achieved through the following technical solutions:

[0008] Determine the energy storage system configuration parameters based on the power system parameters, including: determine the energy storage frequency modulation coefficient, active power and energy required to be configured for the energy storage system;

[0009] The determining of the energy storage frequency modulation coefficient that needs to be configured for the energy storage system includes: calculating the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient of the power system;

[0010] Based on the energy storage system configuration parameters and known operating data, an energy storage converter control strategy is established.

[0011] Optional,

[0012] Determining the energy storage system configuration parameters according to the power system parameters includes:

[0013] Determine the energy storage frequency regulation coefficient that needs to be configured for the energy storage system based on the power system parameters;

[0014] According to the energy storage frequency modulation coefficient, the active power configured by the energy storage system is calculated and obtained;

[0015] Based on the active power, the energy of the energy storage system configuration is determined.

[0016] Optional,

[0017] Determining the energy storage frequency modulation coefficient that needs to be configured for the energy storage system according to the power system parameters includes:

[0018] Calculate the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirements after the power system generates the maximum power fluctuation;

[0019] Calculate the frequency regulation coefficient of the synchronous unit in the power system;

[0020] Based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, a transient attenuation frequency modulation coefficient with time as the variable decay is added to the power system;

[0021] According to the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is calculated and obtained.

[0022] Optional,

[0023] The energy storage converter control strategy is established based on the energy storage system configuration parameters and known operating data, including:

[0024] Build an outer loop control strategy to calculate and output the reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter according to the configuration parameters and operating data of the energy storage system;

[0025] An inner loop control strategy is established to obtain reference values ​​of the d-axis and q-axis components of the energy storage inverter voltage according to the reference value of the d-axis current and the reference value of the q-axis current at the output side of the energy storage inverter.

[0026] Optional,

[0027] The outer loop control strategy is constructed to calculate and output reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter power supply according to the configuration parameters and operation data of the energy storage system, including:

[0028] Building an active loop, adjusting the d-axis current on the output side of the energy storage inverter power supply in response to the frequency change of the power system, and obtaining a reference value of the d-axis current on the output side of the energy storage inverter power supply;

[0029] A reactive loop is constructed to maintain the voltage stability of the power system by adjusting the q-axis current on the output side of the energy storage inverter power supply, and a reference value of the q-axis current on the output side of the energy storage inverter power supply is obtained.

[0030] Optional,

[0031] The transient attenuation frequency modulation coefficient supplemented with time-variable attenuation for the power system based on the transient frequency demand of the power system and the natural logarithmic exponential attenuation function is:

[0032]

[0033] in, K t is the transient attenuation frequency modulation coefficient; e is the natural logarithm; t For time; β is the attenuation coefficient; n is the sum of the units whose primary frequency modulation steady-state output time is greater than the set required time.

[0034] Optional,

[0035] The method further comprises:

[0036] The grid-connected inverter is used as the energy storage converter.

[0037] The present invention also provides an energy storage system configuration system for implementing the aforementioned method, the system comprising:

[0038] The parameter configuration module is used to determine the configuration parameters of the energy storage system according to the power system parameters, including: determining the energy storage frequency modulation coefficient, active power and energy that the energy storage system needs to configure;

[0039] A frequency modulation coefficient module, used to calculate the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient of the power system;

[0040] The control strategy module is used to build an energy storage converter control strategy based on the energy storage system configuration parameters and known operating data.

[0041] Optional,

[0042] The parameter configuration module is also configured to:

[0043] Determine the energy storage frequency regulation coefficient that needs to be configured for the energy storage system based on the power system parameters;

[0044] According to the energy storage frequency modulation coefficient, the active power configured by the energy storage system is calculated and obtained;

[0045] Based on the active power, the energy of the energy storage system configuration is determined.

[0046] Optional,

[0047] The parameter configuration module is also configured to:

[0048] Calculate the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirements after the power system generates the maximum power fluctuation;

[0049] Calculate the frequency regulation coefficient of the synchronous unit in the power system;

[0050] Based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, a transient attenuation frequency modulation coefficient with time as the variable decay is added to the power system;

[0051] According to the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is calculated and obtained.

[0052] Optional,

[0053] The control strategy module is also configured to:

[0054] Build an outer loop control strategy to calculate and output the reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter according to the configuration parameters and operating data of the energy storage system;

[0055] An inner loop control strategy is established to obtain reference values ​​of the d-axis and q-axis components of the energy storage inverter voltage according to the reference value of the d-axis current and the reference value of the q-axis current at the output side of the energy storage inverter.

[0056] Optional,

[0057] The control strategy module is also configured to:

[0058] Building an active loop, adjusting the d-axis current on the output side of the energy storage inverter power supply in response to the frequency change of the power system, and obtaining a reference value of the d-axis current on the output side of the energy storage inverter power supply;

[0059] A reactive loop is constructed to maintain the voltage stability of the power system by adjusting the q-axis current on the output side of the energy storage inverter power supply, and a reference value of the q-axis current on the output side of the energy storage inverter power supply is obtained.

[0060] Optional,

[0061] The transient attenuation frequency modulation coefficient supplemented with time-variable attenuation for the power system based on the transient frequency demand of the power system and the natural logarithmic exponential attenuation function is:

[0062]

[0063] in, K t is the transient attenuation frequency modulation coefficient; e is the natural logarithm; t For time; β is the attenuation coefficient; n is the sum of the units whose primary frequency modulation steady-state output time is greater than the set required time.

[0064] Optional,

[0065] The system is also configured to:

[0066] The grid-connected inverter is used as the energy storage converter.

[0067] The present invention also provides a computer-readable storage medium storing one or more programs, which, when executed, can implement the aforementioned energy storage system configuration method.

[0068] The present invention also provides a device, comprising a processor, a communication interface, a computer-readable storage medium and a communication bus; wherein the processor, the communication interface and the computer-readable storage medium communicate with each other via the communication bus;

[0069] The processor is configured to execute a program stored in a computer-readable storage medium.

[0070] Compared with the prior art, the present invention has the following advantages:

[0071] 1. The energy storage system configuration method proposed in the present invention determines the energy storage system configuration parameters based on the power system parameters, and builds an energy storage converter control strategy based on the attenuation function to control the energy storage output. It can realize automatic adjustment of the output power of the energy storage system, improve the system transient frequency over-limit situation, and improve the controllability of the transient output of the energy storage system.

[0072] 2. The configuration capacity of the energy storage system is determined based on the power system structure, the frequency regulation coefficient of the synchronous unit and the response characteristics of the speed regulator. The poor synchronization between the generator set and the energy storage system and between the generator sets in the frequency support work of the system is taken into account, and the influence of the dynamic frequency dispersion in the system is avoided. By supplementing the transient attenuation frequency regulation coefficient that decays with time as a variable, the virtual frequency regulation coefficient of the energy storage system is changed, which reduces the steady-state frequency deviation and frequency over-limit amplitude after the power system generates power fluctuations, and solves the problem of transient frequency over-limit during the system frequency regulation process.

[0073] 3. By improving the traditional droop control strategy, a converter control strategy based on the attenuation function to control the energy storage output is constructed. The grid-connected control structure is simple, clear and easy to implement, which reduces the input window of the collection amount and solves the problem that only a proportional input-output relationship can be established in the traditional droop control scheme. The control structure design is simplified, and while ensuring the system steady-state frequency deviation requirements, the problems of complex and high-order traditional virtual synchronous machine control methods and obvious coupling between control parameters are solved.

[0074] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0076] Figure 1 A schematic diagram of a process for configuring an energy storage system is shown;

[0077] Figure 2 A schematic block diagram of the structure of the energy storage system configuration system is shown;

[0078] Figure 3 A schematic diagram of the control strategy structure of the energy storage grid-connected inverter according to an embodiment of the present invention is shown;

[0079] Figure 4 A schematic diagram of the inner loop control structure of the energy storage grid-connected inverter according to an embodiment of the present invention is shown;

[0080] Figure 5 A schematic diagram of a four-region equivalent power system according to an embodiment of the present invention is shown;

[0081] Figure 6 A schematic diagram of an energy storage power supply grid-connected system according to an embodiment of the present invention is shown;

[0082] Figure 7 A schematic diagram of a conventional virtual synchronous machine control method is shown;

[0083] Figure 8 A schematic diagram of a conventional droop control method is shown;

[0084] Fig. 9 The schematic diagram of the frequency response of the power system after different power increments are generated under different energy storage control schemes is shown;

[0085] Fig.10 The schematic diagram of the frequency response waveform of the power system after improving the control parameter values ​​in Scheme II and Scheme III is shown;

[0086] Fig.11 The schematic diagram of the output of the energy storage system under three schemes is shown;

[0087] Fig.12 The schematic diagram of the output of different nodes of the energy storage system under three schemes is shown;

[0088] Fig.13 It is a structural schematic diagram of a device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0089] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0090] See attached Figure 1 , the method of the present invention comprises:

[0091] S1. Determine the energy storage system configuration parameters according to the power system parameters, including: determine the energy storage frequency modulation coefficient, active power and energy required to be configured for the energy storage system;

[0092] Among them, according to the power system parameters, the energy storage frequency regulation coefficient that needs to be configured for the energy storage system is determined;

[0093] According to the energy storage frequency modulation coefficient, the active power configured by the energy storage system is calculated and obtained;

[0094] Based on the active power, determining the energy of the energy storage system configuration,

[0095] S2, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is determined, including: calculating the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient of the power system;

[0096] Among them, the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirement after the power system generates the maximum power fluctuation is calculated;

[0097] Calculate the frequency regulation coefficient of the synchronous unit in the power system;

[0098] Based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, a transient attenuation frequency modulation coefficient with time as the variable decay is added to the power system;

[0099] The energy storage frequency modulation coefficient required to be configured for the energy storage system is calculated based on the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient.

[0100] Among them, based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, the transient attenuation frequency modulation coefficient supplemented with time as the variable attenuation for the power system is:

[0101]

[0102] in, K t is the transient attenuation frequency modulation coefficient; e is the natural logarithm; t For time; β is the attenuation coefficient; n is the sum of the units whose primary frequency modulation steady-state output time is greater than the set required time.

[0103] S3. Building an energy storage converter control strategy based on the energy storage system configuration parameters and known operating data.

[0104] Among them, an outer loop control strategy is built to calculate and output the reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter power supply according to the configuration parameters and operating data of the energy storage system;

[0105] An inner loop control strategy is established to obtain the reference values ​​of the d-axis and q-axis components of the energy storage inverter voltage according to the reference value of the d-axis current and the reference value of the q-axis current at the output side of the energy storage inverter.

[0106] Among them, an active loop is built, and a reference value of the d-axis current on the output side of the energy storage inverter power supply is obtained by adjusting the d-axis current on the output side of the energy storage inverter power supply in response to the frequency change of the power system;

[0107] A reactive loop is constructed to maintain the voltage stability of the power system by adjusting the q-axis current on the output side of the energy storage inverter power supply, and a reference value of the q-axis current on the output side of the energy storage inverter power supply is obtained.

[0108] Among them, the grid-connected inverter is used as the energy storage converter.

[0109] Specifically,

[0110] 1. Determine the energy storage system configuration parameters.

[0111] Determine the energy storage system configuration parameters based on the power system parameters.

[0112] 1. Determine the energy storage frequency modulation coefficient that needs to be configured for the energy storage system.

[0113] In this embodiment, in order to reduce the steady-state frequency deviation and frequency over-limit amplitude after the power system generates power fluctuations, and simplify the control structure design of the energy storage system, the implementation method is to use the attenuation function as a medium to change the energy storage frequency modulation coefficient of the energy storage system.

[0114] According to the power system parameters, determine the energy storage frequency regulation coefficient that the energy storage system needs to configure, including:

[0115] Calculate the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirements after the power system generates the maximum power fluctuation;

[0116] Calculate the frequency regulation coefficient of the synchronous unit in the power system;

[0117] Based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, a transient attenuation frequency modulation coefficient with time as the variable decay is added to the power system;

[0118] According to the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is calculated and obtained.

[0119] (1) Maximum power fluctuation frequency coefficient.

[0120] Based on the primary frequency regulation formula and power system parameters, the maximum power fluctuation frequency regulation coefficient required to meet the steady-state frequency deviation requirement after the power system generates the maximum power fluctuation can be calculated according to formula (1): K s :

[0121] (1)

[0122] Among them, Δ f is the frequency deviation allowed by the system; Δ P m is the maximum unbalanced power of the system.

[0123] (2) Frequency regulation coefficient of synchronous unit.

[0124] According to the power system parameters, the frequency regulation coefficient of the synchronous unit in the power system can be calculated by formula (2): K y :

[0125] (2)

[0126] Where m is the number of synchronous machine units in the system; σ is the regulation coefficient of the synchronous unit; S is the capacity of the synchronous unit; f n is the rated frequency of the system.

[0127] (3) Transient attenuation frequency modulation coefficient.

[0128] Based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, the power system is supplemented with time t is the transient attenuation frequency modulation coefficient of variable attenuation K t .

[0129] According to formula (3), we can calculate the time t is the transient attenuation frequency modulation coefficient of variable attenuation K t :

[0130] (3)

[0131] in, e is the natural logarithm; t For time; β is the attenuation coefficient; n is the sum of the units whose primary frequency modulation steady-state output time is greater than the set required time.

[0132] (4) Energy storage frequency modulation coefficient.

[0133] Frequency modulation coefficient according to maximum power fluctuation K s , frequency regulation coefficient of synchronous unit K y and transient attenuation frequency modulation coefficient K t , the energy storage frequency regulation coefficient that needs to be configured for the energy storage system can be calculated by formula (4) K e :

[0134] (4)

[0135] 2. According to the energy storage frequency modulation coefficient, calculate and obtain the active power configured by the energy storage system.

[0136] In this embodiment, the time t Take 0, that is, in the initial response state, according to formula (5), K e With -Δ f The product of can be used to obtain the active power of the energy storage system configuration P e :

[0137] (5)

[0138] 3. Based on the active power, determine the energy of the energy storage system configuration.

[0139] According to formula (6), the energy of the energy storage system configuration can be calculated E e :

[0140] (6)

[0141] in, T It is the time scale of one frequency modulation of the system (usually 15min~20min).

[0142] 2. Based on the energy storage system configuration parameters and known operating data, establish an energy storage converter control strategy.

[0143] Based on the energy storage system configuration parameters and known operating data, an energy storage converter control strategy is established, including:

[0144] Build an outer loop control strategy to calculate and output the reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter according to the configuration parameters and operating data of the energy storage system;

[0145] An inner loop control strategy is established to obtain reference values ​​of the d-axis and q-axis components of the energy storage inverter voltage according to the reference value of the d-axis current and the reference value of the q-axis current at the output side of the energy storage inverter.

[0146] 1. Outer loop control strategy.

[0147] The outer loop control strategy is constructed to calculate and output reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter power supply according to the configuration parameters and operation data of the energy storage system, including:

[0148] Building an active loop, adjusting the d-axis current on the output side of the energy storage inverter power supply in response to the frequency change of the power system, and obtaining a reference value of the d-axis current on the output side of the energy storage inverter power supply;

[0149] A reactive loop is constructed to maintain the voltage stability of the power system by adjusting the q-axis current on the output side of the energy storage inverter power supply, and a reference value of the q-axis current on the output side of the energy storage inverter power supply is obtained.

[0150] In this embodiment, a grid-connected inverter can be used as an energy storage converter. In order to make the energy storage system have active power-frequency regulation characteristics similar to those of a synchronous unit, a control strategy for the grid-connected inverter needs to be established. The active power loop can be established according to formula (7) to simulate the primary frequency regulation and inertia support functions of the synchronous machine:

[0151] (7)

[0152] in, i dr is the d-axis current at the output side of the energy storage inverter i d Reference value of i odr is the d-axis current of the energy storage inverter on the grid side i od Reference value of U dc is the DC side voltage of the grid-connected inverter; f r The frequency reference value of the energy storage grid connection point; f t It is the measured value of the frequency at the energy storage grid connection point.

[0153] In this implementation, the frequency reference value of the energy storage grid connection point is f r The measured value of frequency f t The difference is the start signal, and the frequency modulation coefficient K e The product of is used as the reference value of the d-axis current on the output side of the energy storage inverter power supply. i dr By adjusting the reference value of the d-axis current on the output side of the energy storage inverter, the energy storage inverter can effectively participate in the primary frequency modulation and help the system maintain frequency stability through the inertia support function.

[0154] According to formula (8), a reactive loop can be built to simulate the voltage stabilization function of the synchronous machine. By adjusting the reactive output, the grid voltage can be kept within a suitable range. Based on the voltage droop coefficient, a reference value is provided for the q-axis current on the output side of the energy storage inverter power supply:

[0155] (8)

[0156] in, i qr is the q-axis current at the output side of the energy storage inverter iq The reference value of i oqr is the q-axis current of the energy storage inverter on the grid side i oq The reference value of Q e is the voltage regulation droop coefficient, u odr is the d-axis voltage of the energy storage inverter on the grid side u od The reference value of u d is the d-axis voltage at the output side of the energy storage inverter.

[0157] In this embodiment, an outer loop control strategy of the energy storage grid-connected inverter is formed by building an active loop and a reactive loop.

[0158] 2. Inner loop control strategy.

[0159] In this embodiment, the outer loop control strategy outputs i dr and i qr The reference values ​​of the d-axis and q-axis components of the output energy storage inverter voltage after inner loop control u dr and u qr , the inner loop control state and output equations are shown below:

[0160]

[0161]

[0162]

[0163]

[0164] in, i d and i q is the d-axis component of the output current of the energy storage inverter; u ud , u uq The output voltage of the inner loop control integrator; K 11 , K 12 , K 21 , K 21 , ω n 、L gIt is the proportional and integral adjustment coefficient of the PI controller in the inner loop control.

[0165] Through the inner loop control strategy, the output is adjusted using PI control based on the reference value and the actual measurement value to ensure that the system remains in the target state.

[0166] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0167] See attached Figure 2 , shows the structure of an energy storage system configuration system for implementing the above method, including a parameter configuration module, a frequency modulation coefficient module, and a control strategy module.

[0168] The parameter configuration module is used to determine the energy storage system configuration parameters according to the power system parameters, including: determining the energy storage frequency modulation coefficient, active power and energy that the energy storage system needs to configure;

[0169] The frequency modulation coefficient module is used to calculate the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient of the power system;

[0170] The control strategy module is used to build an energy storage converter control strategy based on the energy storage system configuration parameters and known operating data.

[0171] Figure 3 Schematic diagram of the control strategy structure of the energy storage grid-connected inverter according to an embodiment of the present invention. The control strategy includes outer loop control and inner loop control, wherein the outer loop control structure includes an active loop and a reactive loop.

[0172] Active loop according to the frequency reference value of energy storage grid connection point f r And the frequency reference value of the energy storage grid connection point f t , combined with the d-axis current on the grid-connected side of the energy storage inverter i od Reference value i odr , output d-axis current on the output side of the energy storage inverter i d Reference value i dr .

[0173] The reactive loop is based on the d-axis voltage at the output side of the energy storage inverter. u d And the d-axis voltage of the energy storage inverter grid-connected side u od Reference value u odr , combined with the q-axis current on the grid-connected side of the energy storage inverter i oqReference value i oqr , output energy storage inverter output side q axis current i q Reference value i qr .

[0174] The output of the outer loop control i dr and i qr Input inner loop control, output energy storage inverter power supply voltage d-axis and q-axis component reference value u dr and u qr .

[0175] Figure 4 FIG. 1 is a schematic diagram of the inner loop control structure of the energy storage grid-connected inverter according to an embodiment of the present invention. i dr and i qr , combined with the d-axis component of the output current of the energy storage inverter i d and i q Based on the proportional and integral adjustment coefficients of the PI controller in the inner loop control, the d-axis and q-axis component reference values ​​of the energy storage inverter power supply voltage are output u dr and u qr .

[0176] Figure 5 This is a schematic diagram of a four-area equivalent power system according to an embodiment of the present invention. The specific implementation of the present invention is described in detail below in conjunction with a simulation example.

[0177] The total installed capacity of the power system is 224.8MVA, of which the capacity of synchronous groups G1 and G2 is 31.2MVA, and the capacity of G3 and G4 is 25MVA. The active power of wind turbine groups W1, W2, W3, and W4 is 18MW and operates at maximum power. The total active load L1 to L6 is 145MW. The adjustment coefficient of the synchronous unit is 0.04, the inertia constant is 8s, and the allowable steady-state frequency deviation of the power system is Δ f The magnitude is 0.2Hz, and the maximum power fluctuation Δ P m The setting is 14.5MW with a deadband of ±0.1Hz.

[0178] The method of the embodiment of the present invention is used to obtain the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirement after the power system generates the maximum power fluctuation according to the primary frequency modulation formula. K s for:

[0179]

[0180] Without considering the reduction of the active power of the power system load and the frequency regulation of the wind turbine, the primary frequency regulation process of the power system is completely undertaken by the four synchronous groups (G1, G2, G3, G4). According to the regulation coefficient, capacity and rated frequency (50 Hz) of the synchronous group in the power system, the frequency regulation coefficient of the synchronous unit in the power system can be obtained: K y for:

[0181]

[0182] The time scale of primary frequency regulation of the power system is usually within 15 minutes. Since there are differences in the speed regulator action time of the synchronous machine unit in response to the primary frequency regulation, the stable speed time required to complete the primary frequency regulation is about 2s~20s. Therefore, the transient process of the synchronous machine unit is relatively complex, the inertia support and the primary frequency regulation process are coupled with each other, and the transient frequency of the system is prone to over-limit. Compared with traditional synchronous units, energy storage systems controlled by power electronic devices can respond to frequency regulation faster. In this embodiment, based on the natural logarithmic exponential decay function, the system is supplemented with a frequency modulation coefficient that decays with time t as a variable. K t , thus providing power support for the system in a short time scale. Considering the scale and structure of the power system in the example, the steady-state recovery time is set within 10s, the capacity of the unit with a frequency regulation steady-state output time above 10s is 15MVA, and the attenuation coefficient β is set to 1, then the transient attenuation can be calculated. K t for:

[0183]

[0184] according to K s , K y , K t The energy storage frequency modulation coefficient that needs to be configured for the energy storage system can be obtained K e for:

[0185]

[0186] When t is 0, K eWith -Δ f The active power of the energy storage system can be obtained by multiplying P e :

[0187]

[0188] If the system frequency modulation time scale T If 20 minutes (1200 seconds) is selected, the energy storage system configuration energy E e for:

[0189]

[0190] Based on the configuration parameters and operation data of the energy storage system, the control strategy of the grid-connected inverter of the energy storage system is established. f r The measured value of frequency f t The difference is the start signal, and the frequency modulation coefficient K e The product of is used as the reference value of the d-axis current on the output side of the energy storage inverter power supply. i dr Since the energy storage system in this example is only used as a frequency modulation power source, the island mode operation is not considered. i d and i q The initial reference value i odr and i oqr If both are set to zero, i dr The expression can be simplified to:

[0191]

[0192] Build a reactive loop for droop control to Q e As the voltage droop coefficient, it provides a reference value for the q-axis current on the output side of the energy storage inverter power supply i qr :

[0193]

[0194] i dr and i qr The reference values ​​of the d-axis and q-axis components of the output energy storage inverter voltage after inner loop control u dr and uqr , the inner loop control state and output equations are shown below:

[0195]

[0196]

[0197]

[0198]

[0199] Figure 6 This is a schematic diagram of the energy storage power grid-connected system of an embodiment of the present invention, showing the process of building the energy storage system control solution and signal acquisition.

[0200] The energy storage system is controlled by the converter output and filtered by the inductor L 0 and filter capacitors C 0 After that, it is connected to the grid-connected node PCC. The short-circuit impedance from the grid-connected node to the infinite grid is Z 1 In addition to the above artificially set control parameters, the remaining variables are taken from the measured values ​​of voltage and current on the output side and the grid-connected side of the energy storage converter, that is, i abc , u abc , i oabc , u oabc After coordinate transformation, it becomes i od , i oq , u od , u oq 、i d , i q , u d , u q In the proposed control scheme, u d , u q The output after passing through the phase-locked loop (PLL) becomes the actual measured value of the system frequency. f t , f t and u d They are respectively used as the input of the improved droop control, and the calculated output is the reference value of the d-axis current on the output side of the energy storage inverter power supply.i dr The reference value of the q-axis current i qr , the output is the inverter power supply voltage after the inner loop control u dr and u qr , and finally the energy storage output is controlled after PWM modulation.

[0201] In order to verify the effectiveness of the energy storage configuration method of the present invention and compare its regulation effect with traditional virtual synchronous machine control and traditional droop control, simulation example systems using different control schemes are built under the DIgSILENT / PowerFactory simulation background for comparison. Figure 5 As shown in the figure, the traditional virtual synchronous machine control method is as follows Figure 7 As shown in the figure, the traditional droop control method is as follows Figure 8 shown.

[0202] like Figure 7 The characteristic of the virtual synchronous machine control shown is that the frequency modulation process of the synchronous machine is simulated by the rotor motion equation in the active loop, and a virtual power angle is provided for the converter. θ , in order to improve the response speed and synchronization rate of energy storage frequency regulation. D e is the virtual damping coefficient of the energy storage system, H e is the virtual inertia constant of the energy storage system, P t is the output power of the energy storage system, u t is the grid-connected node voltage of the energy storage system, u abcr is the grid-connected node reference voltage of the energy storage system, θ is the energy storage virtual power angle, E is the virtual electromotive force of energy storage, E r is the reference value of the energy storage virtual electromotive force. Since the relevant introduction of the virtual synchronous machine has been described in detail in a large number of literatures and has a certain degree of common knowledge, this patent will not repeat it.

[0203] like Figure 8 The traditional droop control method shown adds a proportional link with the frequency change rate df / dt as a variable to achieve the supplement of inertia in the transient frequency support.

[0204] Without considering the influence of wind turbines participating in system frequency regulation, the dynamic behavior of the simulation example system after a sudden power increase is simulated, and then the frequency response of the power system and the frequency support characteristics of the energy storage system under different control methods are analyzed.

[0205] Fig. 9 The frequency response diagram of the power system after generating different power increments under different energy storage control schemes. Among them, Scheme I is the energy storage system configuration model of the present invention, Scheme II is the virtual synchronous machine control model, and Scheme III is the traditional droop control model. In order to avoid the influence of the accidental value of the control parameters in Schemes II and III, in Scheme I, K e The size is the calculation configuration result based on the embodiment of the present invention, that is, 16.3+7.5 e -t In Scheme II, K e The size of is 16.3, that is, the configuration result of adding the attenuation function is not considered in the traditional control scheme. H e is 8, D e is 0.5, H e and D e The size of is consistent with the corresponding parameters of the traditional units in the system; similarly, in Scheme III, K e The size is 16.3, H e is 8. Fig. 9 As shown in the figure, after the power system generates unbalanced power, the system frequency response under the three energy storage control strategies can meet the system requirements. Compared with virtual synchronous machine control and traditional droop control, the scheme of the present invention can reduce the frequency drop range and reduce frequency over-limit.

[0206] Fig.10 In order to improve the frequency response waveform diagram of the power system after the control parameters in Scheme II and Scheme III are taken, the experiment is to improve the frequency response waveform diagram of the power system after the control parameters in Scheme II and Scheme III are taken. In order to further highlight the effectiveness and irreplaceability of the energy storage system configuration method of the present invention, the experiment is to improve the frequency response waveform diagram of the power system after the control parameters in Scheme II and Scheme III are taken. K e , H e , D e And in Scheme III H e The value of is obtained to obtain the frequency response waveform of the system. Fig.10 It can be seen that in Scheme II, the improvement K e The value of can improve the lowest point of frequency drop to a certain extent, but its improvement effect is not obvious. In addition,K e The increase of will increase the steady-state output of the energy storage system and reduce the support time of the energy storage system. H e The increase can increase the system inertia and reduce the frequency drop rate, but the improvement effect on the frequency drop amplitude is not obvious, and it will significantly prolong the steady-state recovery time of the system, so it is not recommended. D e The oscillation mode that mainly affects the system frequency, within a certain range, its influence on the lowest point of the system frequency drop is similar to the attenuation function in the present invention, but D e If the value is too high or too low, it will prolong the steady-state recovery time of the frequency, which is not conducive to system stability. H e The impact of the value is similar to that in Scheme II H e It can be seen from the comparison that the method of the present invention has a reliable effect on improving the system frequency over-limit situation and has low coupling.

[0207] Fig.11 The following is a schematic diagram of the output of the energy storage system under three schemes. After the inertia support link, the active output of the energy storage system can remain stable.

[0208] Fig.12 The diagram is a schematic diagram of the output of different nodes of the energy storage system under three schemes. Compared with the virtual synchronous machine control and the traditional droop control, in the scheme of the present invention, the transient output of the energy storage system is not affected by the energy storage grid-connected node, and its output form is more controllable.

[0209] In addition, an embodiment of the present invention further provides an energy storage system configuration device, including:

[0210] A parameter configuration module determines the configuration parameters of the energy storage system according to the power system parameters; wherein, according to the power system parameters, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is determined; according to the energy storage frequency modulation coefficient, the active power configured for the energy storage system is calculated and obtained; based on the active power, the energy configured for the energy storage system is determined.

[0211] The frequency modulation coefficient module is used to calculate the maximum power fluctuation frequency modulation coefficient, synchronous unit frequency modulation coefficient and transient attenuation frequency modulation coefficient of the power system; wherein, the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirement after the power system generates the maximum power fluctuation is calculated; the frequency modulation coefficient of the synchronous unit in the power system is calculated; based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, the transient attenuation frequency modulation coefficient that decays with time as a variable is supplemented for the power system; according to the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is calculated.

[0212] A control strategy module is provided to build an energy storage converter control strategy based on the energy storage system configuration parameters and known operating data; wherein, an outer-loop control strategy is built to calculate and output reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter according to the configuration parameters and operating data of the energy storage system; and an inner-loop control strategy is built to obtain reference values ​​of the d-axis and q-axis components of the energy storage inverter voltage according to the reference values ​​of the d-axis current and the reference values ​​of the q-axis current on the output side of the energy storage inverter.

[0213] Based on the same inventive concept, the present invention also provides a computer-readable storage medium storing one or more programs, which, when executed, can implement the aforementioned energy storage system configuration method.

[0214] like Fig.13 As shown, an embodiment of the present invention further provides a device, including a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus.

[0215] The memory is a computer-readable storage medium for storing one or more programs.

[0216] The processor is used to execute the program stored in the computer-readable storage medium.

[0217] The computer-readable storage medium may be included in the device / apparatus described in the above embodiments; or may exist independently without being assembled into the device / apparatus.

[0218] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for configuring an energy storage system, characterized in that: include: Determine the energy storage system configuration parameters based on the power system parameters, including: determine the energy storage frequency modulation coefficient, active power and energy required to be configured for the energy storage system; The energy storage frequency modulation coefficient that needs to be configured for the energy storage system is determined, including: calculating the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient of the power system; calculating the energy storage frequency modulation coefficient: energy storage frequency modulation coefficient = maximum power fluctuation frequency modulation coefficient - synchronous unit frequency modulation coefficient + transient attenuation frequency modulation coefficient; wherein the transient attenuation frequency modulation coefficient is: in, K t is the transient attenuation frequency modulation coefficient; e is the natural logarithm; t For time; β is the attenuation coefficient; n is the sum of the units whose primary frequency modulation steady-state output time is greater than the set required time; f n is the system rated frequency; σ is the regulation coefficient of the synchronous unit; S is the capacity of the synchronous unit; Based on the configuration parameters of the energy storage system and known operating data, a control strategy for an energy storage converter is established, including: establishing an outer loop control strategy, calculating and outputting reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter according to the configuration parameters and operating data of the energy storage system; establishing an inner loop control strategy, obtaining reference values ​​of the d-axis and q-axis components of the energy storage inverter voltage according to the reference values ​​of the d-axis current and the reference values ​​of the q-axis current on the output side of the energy storage inverter; wherein, the establishment of the outer loop control strategy, calculating and outputting reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter according to the configuration parameters and operating data of the energy storage system, includes: establishing an active loop, adjusting the d-axis current on the output side of the energy storage inverter in response to changes in the frequency of the power system, and obtaining a reference value of the d-axis current on the output side of the energy storage inverter; establishing a reactive loop, maintaining the voltage stability of the power system by adjusting the q-axis current on the output side of the energy storage inverter, and obtaining a reference value of the q-axis current on the output side of the energy storage inverter; wherein, the establishment of the active loop includes: in, i dr is the d-axis current at the output side of the energy storage inverter i d Reference value of i odr is the d-axis current of the energy storage inverter on the grid side i od Reference value of U dc is the DC side voltage of the grid-connected inverter; K e is the energy storage frequency modulation coefficient; f r The frequency reference value of the energy storage grid connection point; f t is the measured value of the frequency at the energy storage grid connection point; the construction of the reactive loop includes: in, i qr is the q-axis current at the output side of the energy storage inverter i q The reference value of i oqr is the q-axis current of the energy storage inverter on the grid side i oq The reference value of Q e is the voltage regulation droop coefficient, u odr is the d-axis voltage of the energy storage inverter on the grid side u od The reference value of u d is the d-axis voltage at the output side of the energy storage inverter.

2. The energy storage system configuration method according to claim 1, characterized in that: Determining the energy storage system configuration parameters according to the power system parameters includes: Determine the energy storage frequency regulation coefficient that needs to be configured for the energy storage system based on the power system parameters; According to the energy storage frequency modulation coefficient, the active power configured by the energy storage system is calculated and obtained; Based on the active power, the energy of the energy storage system configuration is determined.

3. The energy storage system configuration method according to claim 2, characterized in that: Determining the energy storage frequency modulation coefficient that needs to be configured for the energy storage system according to the power system parameters includes: Calculate the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirements after the power system generates the maximum power fluctuation; Calculate the frequency regulation coefficient of the synchronous unit in the power system; Based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, a transient attenuation frequency modulation coefficient with time as the variable decay is added to the power system; According to the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is calculated and obtained.

4. The energy storage system configuration method according to any one of claims 1 to 3, characterized in that: The method further comprises: The grid-connected inverter is used as the energy storage converter.

5. An energy storage system configuration system, characterized in that: The system comprises: The parameter configuration module is used to determine the configuration parameters of the energy storage system according to the power system parameters, including: determining the energy storage frequency modulation coefficient, active power and energy that the energy storage system needs to configure; The frequency modulation coefficient module is used to calculate the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient of the power system; calculate the energy storage frequency modulation coefficient: energy storage frequency modulation coefficient = maximum power fluctuation frequency modulation coefficient - synchronous unit frequency modulation coefficient + transient attenuation frequency modulation coefficient; wherein the transient attenuation frequency modulation coefficient is: ,in, K t is the transient attenuation frequency modulation coefficient; e is the natural logarithm; t For time; β is the attenuation coefficient; n is the sum of the units whose primary frequency modulation steady-state output time is greater than the set required time; f n is the system rated frequency; σ is the regulation coefficient of the synchronous unit; S is the capacity of the synchronous unit; A control strategy module is used to build an energy storage converter control strategy based on the energy storage system configuration parameters and known operating data, including: building an outer loop control strategy, calculating and outputting reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter according to the configuration parameters and operating data of the energy storage system; building an inner loop control strategy, obtaining reference values ​​of the d-axis and q-axis components of the energy storage inverter voltage according to the reference value of the d-axis current and the reference value of the q-axis current on the output side of the energy storage inverter; wherein, the outer loop control strategy is built according to The configuration parameters and operation data of the energy storage system are used to calculate and output the reference values ​​of the d-axis and q-axis currents on the output side of the energy storage inverter power supply, including: building an active loop, adjusting the d-axis current on the output side of the energy storage inverter power supply to respond to the frequency change of the power system, and obtaining the reference value of the d-axis current on the output side of the energy storage inverter power supply; building a reactive loop, maintaining the voltage stability of the power system by adjusting the q-axis current on the output side of the energy storage inverter power supply, and obtaining the reference value of the q-axis current on the output side of the energy storage inverter power supply; wherein, building the active loop includes: in, i dr is the d-axis current at the output side of the energy storage inverter i d Reference value of i odr is the d-axis current of the energy storage inverter on the grid side i od Reference value of U dc is the DC side voltage of the grid-connected inverter; f r The frequency reference value of the energy storage grid connection point; f t is the measured value of the frequency at the energy storage grid connection point; the construction of the reactive loop includes: in, i qr is the q-axis current at the output side of the energy storage inverter i q The reference value of i oqr is the q-axis current of the energy storage inverter on the grid side i oq The reference value of Q e is the voltage regulation droop coefficient, u odr is the d-axis voltage of the energy storage inverter on the grid side u od The reference value of u d is the d-axis voltage at the output side of the energy storage inverter.

6. The energy storage system configuration system according to claim 5, characterized in that: The parameter configuration module is also configured to: Determine the energy storage frequency regulation coefficient that needs to be configured for the energy storage system based on the power system parameters; According to the energy storage frequency modulation coefficient, the active power configured by the energy storage system is calculated and obtained; Based on the active power, the energy of the energy storage system configuration is determined.

7. The energy storage system configuration system according to claim 6, characterized in that: The parameter configuration module is also configured to: Calculate the maximum power fluctuation frequency modulation coefficient required to meet the steady-state frequency deviation requirements after the power system generates the maximum power fluctuation; Calculate the frequency regulation coefficient of the synchronous unit in the power system; Based on the transient frequency demand of the power system and the natural logarithmic exponential decay function, a transient attenuation frequency modulation coefficient with time as the variable decay is added to the power system; According to the maximum power fluctuation frequency modulation coefficient, the synchronous unit frequency modulation coefficient and the transient attenuation frequency modulation coefficient, the energy storage frequency modulation coefficient that needs to be configured for the energy storage system is calculated and obtained.

8. The energy storage system configuration system according to any one of claims 5 to 7, characterized in that: The system is also configured to: The grid-connected inverter is used as the energy storage converter.

9. A computer-readable storage medium storing one or more programs, characterized in that: When the one or more programs are executed, the energy storage system configuration method described in any one of claims 1 to 4 can be implemented.

10. An electronic device comprising a processor, a communication interface, the computer-readable storage medium of claim 9, and a communication bus; wherein: The processor, the communication interface, and the computer-readable storage medium communicate electronically with each other via a communication bus; characterized in that: The processor is configured to execute a program stored in a computer-readable storage medium.

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