Energy storage electromechanical transient model construction method and system for analyzing synchronous control equipment grid-connected system characteristics

Abstract

The invention relates to the technical field of digital model construction of network construction type control energy storage power equipment, in particular to an energy storage electromechanical transient model construction method and system for analyzing the characteristics of a synchronous control equipment grid-connected system, and the method comprises the steps: applying double droop control to an energy storage converter system, analyzing a regulation and control principle and grid-connected equivalent external characteristics, constructing a grid-connected equivalent circuit of the double-droop control energy storage converter system; designing the structure of the energy storage converter system; according to the designed energy storage converter system structure, a double-droop control part electromechanical transient model, an energy storage body electromechanical transient model and a grid-connected interface electromechanical transient model are constructed, and a complete energy storage converter control system electromechanical transient model capable of being embedded into a PSASP main interface is formed. And the output power change of the converter is reflected at the access node, so that the functions of characteristic analysis, load flow calculation and the like of a regional power grid system accessed to the energy storage converter can be realized, and a technical scheme is provided for guiding the planning design of accessing the energy storage converter to the regional power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of digital model construction of grid-connected control energy storage power equipment, and in particular to a method and system for constructing an energy storage electromechanical transient model for analyzing the characteristics of a grid-connected system of a synchronous control device. Background Art

[0002] With the increase of new energy power generation units such as photovoltaic and wind power, the proportion of traditional thermal power and hydropower has decreased. The new power system is facing problems such as reduced inertia support capacity, reduced total rotating reserve capacity, and weakened peak, frequency and voltage regulation capabilities. These problems have led to a decline in the stable operation capability of the new power system, a weakened fault self-healing recovery capability, and reduced optimization and regulation performance. To this end, some technical personnel in the power industry proposed to connect energy storage converters to the new power system to complete tasks such as power fluctuation smoothing, frequency and voltage fluctuation suppression, to make up for the lack of rotating reserve capacity in the new power system and the decline in the ability to suppress new energy output fluctuations, thereby improving the new power system's load rate for new energy power generation units.

[0003] Traditional electromechanical transient models of energy storage converters are generally based on grid-following control strategies such as constant power control and V / f control. The accuracy of model construction is not high and the simulation computing capability is not strong, which needs further optimization and improvement. At present, grid-following control strategies, such as droop control and virtual synchronous machine control, have attracted much attention because they can be applied to converters to optimize the external operating characteristics of converters, actively smooth power fluctuations, improve frequency regulation, voltage regulation, anti-disturbance performance and the operating stability of power systems. They are expected to become the key technology to achieve 100% access to new energy.

[0004] In the prior art, regarding the electromechanical transient modeling of energy storage inverters and the analysis of their grid-connected characteristics, existing research literature has proposed an energy storage electromechanical transient characteristics modeling method based on virtual synchronous machine technology. This method implements the model in a user-defined manner in the PSASP software, achieving better optimization capabilities and applicability than traditional models and more accurate operational characteristics characterization, but does not consider the implementation of a new dual droop control strategy; another study discloses a method for constructing an electromechanical transient model of a doubly fed wind turbine, which, based on the doubly fed wind turbine system data, implements the over-limit judgment and setting function of the equivalent current source value of the wind turbine interface network, thereby improving the interactive performance of the wind turbine and the interface power grid, but does not involve research on the construction of an electromechanical transient model of the energy storage inverter system and the analysis of the system grid-connected characteristics, nor does it study new grid-building control strategies. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system, thereby effectively solving the problems in the background technology.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: a method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system, comprising the following steps:

[0007] The dual droop control strategy is applied to the energy storage converter control system, and the regulation principle and grid-connected equivalent external characteristics of the energy storage converter control system are analyzed. Based on the analysis results, the grid-connected equivalent circuit of the dual droop control energy storage converter system is constructed.

[0008] Based on the constructed grid-connected equivalent circuit of the dual droop control energy storage converter system, the structure of the energy storage converter system is designed;

[0009] According to the structure of the designed energy storage converter system, the electromechanical transient model of the dual droop control part in the energy storage converter, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface are constructed;

[0010] The electromechanical transient model of the double droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface are integrated, and the node current injection method is used to obtain a complete electromechanical transient model of the energy storage converter control system that can be embedded in the main interface of the PSASP software.

[0011] Furthermore, the dual droop control strategy specifically includes a signal acquisition and power calculation module, active power / frequency droop control, reactive power / voltage droop control, a current inner loop controller, an output power calculation equation, a power differential equation and an SPWM module.

[0012] Further, the energy storage converter control system includes an energy storage battery pack, a DC / AC converter, an energy management system, a control system and a filter;

[0013] Among them, the energy storage battery pack is used for electric energy storage and electric energy absorption;

[0014] DC / AC converters are used to convert direct current into alternating current suitable for grid connection;

[0015] The energy management system EMS is used to monitor and control the status of battery cells, ensure the consistency between battery cells, and achieve energy distribution management goals;

[0016] The control system is used to monitor the voltage and current signals of the power grid and send control signals to the converter to achieve the goal of stable grid-connected operation of the converter and the bidirectional flow of electric energy to meet the power control needs of the power grid;

[0017] The filter is used to filter out harmonics in the grid-connected output voltage and current.

[0018] Furthermore, the dual droop control strategy is applied to the energy storage converter control system, and the regulation principle and grid-connected equivalent external characteristics of the energy storage converter system are analyzed, specifically:

[0019] Active power / frequency droop control simulates the speed regulator of the synchronous machine, so that the active power and output frequency show droop control characteristics. The corresponding expression is as follows:

[0020] f=f ref -k p (p o -p ref ) (1)

[0021] Where, f is the converter droop control output frequency; f ref is the reference frequency; k p is the active frequency droop control coefficient; p o The active power output of the converter; p ref is the active power reference value;

[0022] The reactive power / voltage droop control simulates the excitation regulator of the synchronous machine, so that the reactive power and AC output voltage present a droop control characteristic. The corresponding expression is as follows:

[0023] u gd =u gref -k q (q o -q ref ) (2)

[0024] In the formula, u gd is the d-axis component of the grid-side voltage output by the converter droop control; u gref is the grid-side voltage reference value; k q is the reactive voltage droop control coefficient; q o The reactive power output of the converter; q ref is the reactive power reference value.

[0025] Furthermore, based on the analysis results, a grid-connected equivalent circuit of a dual droop control energy storage converter system is constructed, including:

[0026] Calculate the current output by the energy storage converter to the grid, as shown in formula (3):

[0027]

[0028] In the formula, I o is the converter output current; U o ∠δ is the output voltage of the converter; U g ∠0 is the grid-side voltage; R f , L fare virtual resistance and virtual inductance respectively; j is the sign of the imaginary part; ω is the reference angular frequency;

[0029] Let the virtual resistor R f is zero, making the equivalent impedance from the converter outlet to the grid side purely inductive, thereby realizing active and reactive power decoupling control, and the output apparent power can be deduced as:

[0030]

[0031] Where U g is the effective value of the grid-side voltage; U o is the effective value of the converter output voltage; is the reference value of the converter output current; U o ∠-δ is the conjugate of the converter output voltage; δ is the output reference phase angle; U g ∠0 is the grid-side voltage; L f are virtual inductance; P o , Q o Active power and reactive power reference value signals output by the converter;

[0032] Further reverse calculation can be performed to obtain the output active power and reactive power of the converter:

[0033]

[0034]

[0035] Where P o , Q o is the reference value signal of active power and reactive power output by the converter; δ is the output reference phase angle.

[0036] Furthermore, based on the constructed dual droop control energy storage converter system model, the structure of the energy storage converter system is designed, specifically:

[0037] The dual droop control energy storage converter system model is composed of a transformed power differential equation model and a dual droop control model;

[0038] The electromechanical transient model of the energy storage converter system includes an energy storage battery pack body model, a DC / AC converter control model and a grid-connected interface model;

[0039] The core component of the energy storage converter system is the DC / AC converter. When the control system changes the control signal, the frequency, amplitude and phase of the grid-connected output voltage can be controlled.

[0040] Furthermore, the control system includes system-level control and inner-loop control, and the coordinated work of the system-level control and the inner-loop control realizes the precise control of the active and reactive power of the power grid by the energy storage converter, specifically:

[0041] System-level control is responsible for performing the main control tasks, including collecting the grid-side angular frequency ω from the power grid. g and grid voltage U g The collected signal is sent to the dual droop controller to calculate the active power P of the grid-connected output o and reactive power Q o Reference value; the energy storage battery pack obtains active power P o and reactive power Q o The reference value signal is then controlled through the energy management system to achieve battery SOC balance and consistency;

[0042] The inner loop control is based on the power reference value signal provided by the system-level control, and is processed using proportional-integral PI control and decoupling control; the processed actual power signal is output to the grid-connected interface model, and the grid-connected interface model converts the output actual power signal into the d-axis and q-axis components of the grid-connected output current of the energy storage inverter to achieve node current injection.

[0043] Furthermore, the structure of the inner loop control is composed of an inner loop control model and a converter model, which includes a PI controller and a decoupling control link;

[0044] Based on the inner loop control, the d-axis and q-axis currents can quickly track the control targets and achieve the decoupling control targets of active power and reactive power. Specifically:

[0045] By removing the coupling link between the inner loop control and the converter model, further deduction can be made to obtain a control structure where the d and q axes are independent of each other, and the transfer functions of the d and q axes are deduced as follows:

[0046]

[0047] In the formula, i odref and i oqref is the reference value of the d-axis and q-axis components of the grid-connected output current; k pi and k ii is the proportional gain and integral gain of the PI controller; u gd and u gq is the reference value of the d-axis and q-axis components of the grid-side voltage; u zd and u zq The inner loop controls the output d-axis and q-axis components; L f is the virtual reactance;

[0048] Using the zero-pole cancellation method, equation (7) is equivalent to a first-order inertia link, and the differential equation for power is:

[0049]

[0050] Where T1 and T2 are the actual power signal P and Q tracking reference value signal P respectively. o and Q o The inertia time constant.

[0051] Furthermore, based on the energy storage converter with dual droop control, the electromechanical transient model of the dual droop control part in the energy storage converter is built through the user-defined interface in the PSASP software, specifically:

[0052] The electromechanical transient model of the dual droop control part includes an active frequency droop control module, a reactive voltage droop control d-axis and q-axis module, an abc / dq forward transformation module, a PI control module, a current inner loop control module with inductor current decoupling, a dq / abc inverse transformation module, an output power calculation module, and a power differential equation module.

[0053] Furthermore, considering the key parameters and constraints of the energy storage body, the electromechanical transient model of the energy storage body is constructed, specifically:

[0054] The key parameters and constraints of the energy storage entity include: SOC calculation, capacity upper and lower limits, charge and discharge speed and power upper and lower limits, converter capacity upper and lower limits, efficiency limits and dead zone limits;

[0055] Energy storage ontology model and constraints, specifically:

[0056]

[0057] Where: SOC is the real-time state of charge of the battery; SOC0 is the initial state of charge of the battery; T disch is the discharge time constant under rated power; P is the actual active power. When it is greater than zero, it indicates charging, and when it is less than zero, it indicates discharging, which is limited by the charging and discharging power; Q is the actual reactive power, which is limited by the converter capacity; SOC min , SOC max is the lower and upper limits of battery capacity; -P max , P max RD is the lower limit and upper limit of output active power; p , R.U. p The lower limit and upper limit of active power conversion rate; -Q max , Q max RD is the lower limit and upper limit of output reactive power; q , R.U. q is the lower limit and upper limit of reactive power conversion rate; η is the operating efficiency; f min 、f max is the lower limit and upper limit of the frequency; S 2 is the square of the output apparent power; P oThe active power output of the converter is derived from the reference value signal.

[0058] Furthermore, the construction of the grid-connected interface electromechanical transient model includes:

[0059] The grid-connected interface model is used to convert the output power of the energy storage converter into current and inject it into the grid model, specifically:

[0060] Convert the control output active power P and reactive power Q;

[0061] Let the real and imaginary parts of the grid voltage be U gR , U gI , combined with I oR ,I oI Substituting into equation (4), we get equation (10), and based on P and Q, we can deduce I oR ,I oI The calculation expression of is shown in formula (11);

[0062]

[0063] Where P is the actual active power. When it is greater than zero, it indicates charging, and when it is less than zero, it indicates discharging. It is limited by the charging and discharging power. Q is the actual reactive power, which is limited by the converter capacity. U gR , U gI Represent the real and imaginary parts of the grid-side voltage respectively; I oR ,I oI Represent the real and imaginary parts of the output current respectively;

[0064] The grid-connected interface electromechanical transient model is constructed through multiplication boxes, addition boxes, and division boxes, and the converter output power is reflected in the system model in the form of node current injection.

[0065] The present invention also provides a system for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system, comprising:

[0066] The dual droop control energy storage converter system model building module applies the dual droop control strategy to the energy storage converter control system, analyzes the regulation principle and grid-connected equivalent external characteristics of the energy storage converter control system, and builds a dual droop control energy storage converter system model based on the analysis results;

[0067] The preliminary design and analysis module of the electromechanical transient model designs the structure of the energy storage converter system based on the constructed dual droop control energy storage converter system model;

[0068] The sub-model construction module constructs the electromechanical transient model of the dual droop control part in the energy storage converter, the electromechanical transient model of the energy storage body, and the electromechanical transient model of the grid-connected interface according to the structure of the designed energy storage converter system;

[0069] The sub-model integration and electromechanical transient model construction module integrates the electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface to obtain a complete electromechanical transient model of the energy storage converter control system that can be embedded in the main interface of the PSASP software.

[0070] The present invention further provides an electronic device, comprising:

[0071] Processor and memory;

[0072] The processor is used to execute the steps of the energy storage electromechanical transient model construction method by calling the program or instruction stored in the memory.

[0073] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a program or instruction, wherein the program or instruction is a step for a computer to execute the method for constructing an energy storage electromechanical transient model.

[0074] The beneficial effects of the present invention are as follows: the patent of the present invention applies a dual droop control energy storage converter system with a simple control structure and active power support, analyzes the control principle and grid-connected equivalent external characteristics of the system, studies its electromechanical transient model, and completes the construction of a digital simulation model of the control system based on the user-defined interface in the PSASP software, designs a software model for grid-connected characteristic analysis and flow calculation of the energy storage converter system with low model complexity and fast calculation speed, and provides a new technical method for grid-connected characteristic analysis, flow calculation, and temporary stability analysis of energy storage converters.

[0075] Double droop control is applied to the control system of energy storage converter. Double droop control improves the traditional droop control, making the reactive power tracking control and AC voltage tracking control performance better. At the same time, it simplifies the voltage and current dual-loop control, so that the overall response rate of the control system is improved, and the converter has the active / frequency and reactive / voltage response external characteristics of the synchronous machine. It can actively provide a certain frequency and voltage support to the power grid, complete the power, frequency and voltage regulation tasks, improve the safe and stable operation performance of the converter, control response flexibility, and optimize the grid-connected operation characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] 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 only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0077] Figure 1 This is the structure diagram of the dual droop control energy storage converter system;

[0078] Figure 2 It is the grid-connected equivalent circuit of the energy storage converter system;

[0079] Figure 3 It is the energy storage converter system structure;

[0080] Figure 4 It is a schematic diagram of the electromechanical transient model of the energy storage converter system;

[0081] Figure 5 It is the inner loop control structure;

[0082] Figure 6 After decoupling, the d and q axes are controlled independently from each other;

[0083] Figure 7 It is the electromechanical transient model of the double droop control part in the energy storage converter;

[0084] Figure 8 The electromechanical transient model corresponding to the active frequency droop control module;

[0085] Fig. 9 It is the electromechanical transient model of the energy storage body;

[0086] Fig.10 It is the electromechanical transient model for the grid-connected interface;

[0087] Fig.11 It is the electromechanical transient model of the energy storage converter control system. DETAILED DESCRIPTION

[0088] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0089] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0090] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0091] like Figures 1 to 11 The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system shown includes the following steps:

[0092] The dual droop control strategy is applied to the energy storage converter control system, and the regulation principle and grid-connected equivalent external characteristics of the energy storage converter control system are analyzed. Based on the analysis results, the grid-connected equivalent circuit of the dual droop control energy storage converter system is constructed.

[0093] like Figure 1 As shown, the dual droop control strategy specifically includes a signal acquisition and power calculation module, active power / frequency droop control, reactive power / voltage droop control, a current inner loop controller, an output power calculation equation, a power differential equation and an SPWM module.

[0094] Figure 3 is the energy storage converter system structure. Figure 3 It can be seen that the energy storage converter control system includes an energy storage battery pack, a DC / AC converter (Power Conversion System, PCS), an energy management system (Energy Management System, EMS), a control system and a filter;

[0095] Among them, the energy storage battery pack is used for electrical energy storage and absorption, and is the energy source of the system.

[0096] The DC / AC converter is used to convert direct current into alternating current suitable for grid connection.

[0097] The energy management system EMS is used to monitor and control the status of battery cells, ensure the consistency between battery cells, and achieve energy distribution management goals;

[0098] The control system is used to monitor the voltage and current signals of the power grid and send control signals to the converter to achieve the goal of stable grid-connected operation of the converter and the bidirectional flow of electric energy to meet the power control needs of the power grid;

[0099] The filter is used to filter out harmonics in the grid-connected output voltage and current to improve the power quality.

[0100] like Figure 1 As shown, the battery pack is connected in parallel with a DC stabilizing capacitor C dcThe three-phase six-bridge-arm DC / AC converter converts direct current into alternating current, and then the AC output voltage and current are smoothed by an LC filter to achieve grid-connected operation. Figure 1 in, u dc is the DC voltage; u mabc is the output modulation voltage of the converter side; i mabc is the output current of the converter side; u oabc is the converter output voltage; i oabc is the output current of the converter; i cabc is the current flowing through capacitor C1; u gabc is the grid-side voltage; L1 is the filter inductor on the converter side; C1 is the filter capacitor; R f is a virtual resistor; L f is the virtual reactance; L g is the grid-side equivalent reactance; p o The active power output of the converter; q o The reactive power output of the converter; p ref is the active power reference value; q ref is the reactive power reference value; k p is the active frequency droop control coefficient; k q is the reactive voltage droop control coefficient; u gref is the grid-side voltage reference value; i odref 、i oqref The current i o The d-axis reference value and q-axis reference value of f ref is the reference frequency; δ is the output reference phase angle; P is the control output active power value; Q is the control output reactive power value; x and X represent the transient quantity and steady-state quantity respectively, which can refer to the variable P or Q in the above; x d 、x q are the d-axis component and q-axis component of the transient quantity x, respectively. d Can refer to u gd , can also refer to u od ;x q Can refer to u gq , can also refer to u oq .

[0101] The double droop control strategy is applied to the energy storage converter control system, and the regulation principle and grid-connected equivalent external characteristics of the energy storage converter system are analyzed. Specifically:

[0102] Active power / frequency droop control simulates the speed regulator of the synchronous machine, so that the active power and output frequency show droop control characteristics. The corresponding expression is as follows:

[0103] f=f ref -k p (p o -pref ) (1)

[0104] Where, f is the converter droop control output frequency; f ref is the reference frequency; k p is the active frequency droop control coefficient; p o The active power output of the converter; p ref is the active power reference value;

[0105] The reactive power / voltage droop control simulates the excitation regulator of the synchronous machine, so that the reactive power and AC output voltage present a droop control characteristic. The corresponding expression is as follows:

[0106] u gd =u gref -k q (q o -q ref ) (2)

[0107] In the formula, u gd is the d-axis component of the grid-side voltage output by the converter droop control; u gref is the grid-side voltage reference value; k q is the reactive voltage droop control coefficient; q o The reactive power output of the converter; q ref is the reactive power reference value.

[0108] like Figure 2 As shown in the figure, based on the analysis results, the grid-connected equivalent circuit of the dual droop control energy storage converter system is constructed, including:

[0109] Figure 2 In, P o , Q o is the active power and reactive power output by the converter; U o ∠δ is the output voltage of the converter; R f , L f are virtual resistance and virtual inductance respectively; U g ∠0 is the grid-side voltage; I o is the converter output current; R c , C c are the equivalent resistance to ground and the equivalent capacitance to ground respectively; L g is the grid-side equivalent reactance;

[0110] Depend on Figure 2 The current output by the energy storage converter to the grid can be calculated as shown in formula (3).

[0111]

[0112] In the formula, I o is the converter output current; Uo ∠δ is the output voltage of the converter; U g ∠0 is the grid-side voltage; R f , L f are virtual resistance and virtual inductance respectively; j is the sign of the imaginary part; ω is the reference angular frequency;

[0113] Let the virtual resistor R f is zero, making the equivalent impedance from the converter outlet to the grid side purely inductive, thereby realizing active and reactive power decoupling control, and the output apparent power can be deduced as:

[0114]

[0115] Where U g is the effective value of the grid-side voltage; U o is the effective value of the converter output voltage; is the reference value of the converter output current; U o ∠-δ is the conjugate of the converter output voltage; δ is the output reference phase angle; U g ∠0 is the grid-side voltage; L f are virtual inductance; P o , Q o is the output active power and reactive power;

[0116] Further reverse calculation can be performed to obtain the output active power and reactive power of the converter:

[0117]

[0118]

[0119] Where P o , Q o is the reference value signal of active power and reactive power output by the converter; δ is the output reference phase angle.

[0120] Double droop control is applied to the control system of energy storage converter. Double droop control improves the traditional droop control, making the reactive power tracking control and AC voltage tracking control performance better. At the same time, it simplifies the voltage and current dual-loop control, so that the overall response rate of the control system is improved, and the converter has the active / frequency and reactive / voltage response external characteristics of the synchronous machine. It can actively provide a certain frequency and voltage support to the power grid, complete the power, frequency and voltage regulation tasks, improve the safe and stable operation performance of the converter, control response flexibility, and optimize the grid-connected operation characteristics.

[0121] Based on the constructed grid-connected equivalent circuit of the dual droop control energy storage converter system, the structure of the energy storage converter system is designed;

[0122] The dual droop control energy storage converter system model is composed of a transformed power differential equation model and a dual droop control model;

[0123] The electromechanical transient model of the energy storage converter system includes an energy storage battery pack body model, a DC / AC converter control model and a grid-connected interface model;

[0124] The core component of the energy storage converter system is the DC / AC converter. When the control system changes the control signal, the frequency, amplitude and phase of the grid-connected output voltage can be controlled.

[0125] As a preferred embodiment of the above scheme, the control system includes system-level control and inner-loop control, and the coordinated work of the system-level control and the inner-loop control realizes the precise control of the active and reactive power of the power grid by the energy storage converter, specifically:

[0126] System-level control is responsible for performing the main control tasks, including collecting the grid-side angular frequency ω from the power grid. g and grid voltage U g The collected signal is sent to the dual droop controller to calculate the active power P of the grid-connected output o and reactive power Q o Reference value; the energy storage battery pack obtains active power P o and reactive power Q o The reference value signal is generated and controlled through the energy management system (EMS) to achieve the balance and consistency of battery SOC and ensure that the operation of the battery pack meets the control requirements;

[0127] The inner loop control is based on the power reference value signal provided by the system-level control, and is processed using proportional-integral PI control and decoupling control; the processed actual power signal is output to the grid-connected interface model, which converts the output actual power signal into the d-axis and q-axis components of the grid-connected output current of the energy storage inverter, realizing node current injection, thereby allowing the energy storage system to effectively exchange electric energy with the power grid.

[0128] In a further preferred embodiment, the structure of the inner loop control is composed of an inner loop control model and a converter model, which includes a PI controller and a decoupling control link;

[0129] Based on the inner loop control, the d-axis and q-axis currents can quickly track the control targets and achieve the decoupling control targets of active power and reactive power. Specifically:

[0130] By removing the coupling link between the inner loop control and the converter model, further deduction can be made to obtain a control structure where the d and q axes are independent of each other, as shown in Figure 6 As shown;

[0131] It can be further deduced that the transfer functions of the d-axis and q-axis are:

[0132]

[0133] In the formula, i odref and i oqref is the reference value of the d-axis and q-axis components of the grid-connected output current; k pi and k ii is the proportional gain and integral gain of the PI controller; u gd and u gq is the reference value of the d-axis and q-axis components of the grid-side voltage; u zd and u zq The inner loop controls the output d-axis and q-axis components; L f is the virtual reactance; refer to Figure 5 The inner loop control structure;

[0134] Using the zero-pole cancellation method, equation (7) is equivalent to a first-order inertia link, and the differential equation for power is:

[0135]

[0136] Where T1 and T2 are the actual power signal P and Q tracking reference value signal P respectively. o and Q o The inertia time constant

[0137] According to the structure of the designed energy storage converter system, the electromechanical transient model of the dual droop control part in the energy storage converter, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface are constructed;

[0138] Based on the energy storage converter with dual droop control, the electromechanical transient model of the dual droop control part in the energy storage converter is built through the user-defined interface in the PSASP software, specifically:

[0139] Figure 7 The electromechanical transient model of the dual droop control part includes an active frequency droop control module, a reactive voltage droop control d-axis and q-axis module, an abc / dq forward transformation module, a PI control module, a current inner loop control module with inductor current decoupling, a dq / abc inverse transformation module, an output power calculation module, and a power differential equation module. Figure 7 The specific meanings of the temporarily defined variables are shown in Table 1.

[0140] Table 1

[0141]

[0142]

[0143] Each module is composed of a differential-integral box, an algebraic operation box, a basic function operation box, a logic control box, and other boxes in a user-defined interface toolbox.

[0144] Here we take the active frequency droop control module as an example to illustrate the construction process, and other modules are not described in detail.

[0145] The active frequency droop control module corresponds to the electromechanical transient model as follows: Figure 8 As shown, the addition box 42 inputs the active power reference value corresponding to the assignment box 43, minus the output active power po, the inertia boxes 50 and 51 simulate the delay caused by the operation, and the multiplication box 44 and the assignment box 45 represent multiplication by the active frequency droop control coefficient k p , the addition box 46 and the assignment box 47 indicate adding the reference frequency f ref , the dead zone box No. 49 corresponds to the frequency dead zone limitation link, see the formula (9) below for details, the integral box No. 52 corresponds to the integral link 1 / s, where K corresponds to 2π. The active frequency droop control characteristics of the converter are reflected through this module.

[0146] Considering the key parameters and constraints of the energy storage body, the electromechanical transient model of the energy storage body is constructed, specifically:

[0147] The differences in mathematical models of different energy storage entities are reflected in the charging and discharging speed, output power, capacity, etc. In the electromechanical transient time scale of a few seconds to tens of milliseconds, the impact of the change of the state of charge (SOC) on the parameters of the energy storage entity can be ignored. The parameters of the energy storage entity, such as the charging and discharging speed, are fixed, and its external characteristics can be equivalent to a straight line. Then, the electromechanical transient model of the energy storage entity can be equivalent to a combination of a series of parameter restriction links. The key parameters and restriction conditions of the energy storage entity include: SOC calculation, upper and lower limits of capacity, upper and lower limits of charging and discharging speed and power, upper and lower limits of converter capacity, efficiency limit and dead zone limit;

[0148] 1) SOC is defined as the percentage of the current power of the battery to the maximum power, which can accurately reflect the remaining available capacity. Reasonable control of SOC can extend the cycle life of the battery. This patent will use a simple ampere-hour method to estimate SOC. In addition, there are open circuit voltage method, neural network prediction method, Kalman filter method, etc.

[0149] 2) The upper and lower capacity limits are used to prevent the battery from overcharging and over-discharging and achieve reasonable control targets for the battery SOC.

[0150] 3) The upper and lower limits of charging and discharging speed and power refer to the upper and lower limits of energy storage charging and discharging speed and charging and discharging power under the physical constraints of the energy storage body.

[0151] 4) The upper and lower limits of converter capacity refer to the upper and lower limits of output active power and output reactive power due to control.

[0152] 5) The energy storage efficiency limitation in this patent refers to the limitation of the single cell operating efficiency affected by the change of battery SOC, which is specifically manifested as the operating efficiency limitation constant.

[0153] 6) Dead zone limit is a set action boundary used to avoid frequent charging and discharging of the converter due to small disturbances.

[0154] Then the energy storage ontology model and constraints can be derived:

[0155]

[0156] Where: SOC is the real-time state of charge of the battery; SOC0 is the initial state of charge of the battery; T disch is the discharge time constant under rated power; P is the actual active power. When it is greater than zero, it indicates charging, and when it is less than zero, it indicates discharging, which is limited by the charging and discharging power; Q is the actual reactive power, which is limited by the converter capacity; SOC min , SOC max is the lower and upper limits of battery capacity; -P max , P max RD is the lower limit and upper limit of output active power; p , R.U. p The lower limit and upper limit of active power conversion rate; -Q max , Q max RD is the lower limit and upper limit of output reactive power; q , R.U. q is the lower limit and upper limit of reactive power conversion rate; η is the operating efficiency; f min 、f max is the lower limit and upper limit of the frequency; S 2 is the square of the output apparent power; P o It is the active power reference value signal output by the converter.

[0157] like Fig. 9 Shown is the electromechanical transient model of the energy storage body. Fig. 9 The specific meanings of the temporary defined variables are shown in Table 2. Boxes 12 and 13 construct the SOC calculation link, boxes 23, 28, 30, and 33 construct the capacity upper and lower limits link, boxes 22, 27, 29, and 32 construct the charging and discharging speed and power upper and lower limits link, and boxes 34, 35, 36, 37, 38, 39, 40, and 41 construct the converter capacity upper and lower limits link, which determines the output of reactive power control. The operating efficiency limit link and the dead zone limit link have been Figure 7The structure is completed by frames 204, 205, and 49.

[0158] Table 2

[0159]

[0160]

[0161] The construction of the grid-connected interface electromechanical transient model includes:

[0162] The grid-connected interface model is used to convert the output power of the energy storage converter into current and inject it into the grid model, specifically:

[0163] The electromechanical transient model of the energy storage converter constructed in the user-defined interface is embedded in the PSASP main interface model based on the node current injection method, and the real part of the active output current I oR , the imaginary part of the active output current I oI To reflect this, it is necessary to convert the control output active power P and reactive power Q;

[0164] Let the real and imaginary parts of the grid voltage be U gR , U gI , combined with I oR ,I oI Substituting into equation (4), we get equation (10), and based on P and Q, we can deduce I oR ,I oI The calculation expression of is shown in formula (11):

[0165]

[0166] Where P is the actual active power. When it is greater than zero, it indicates charging, and when it is less than zero, it indicates discharging. It is limited by the charging and discharging power. Q is the actual reactive power, which is limited by the converter capacity. U gR , U gI Represent the real and imaginary parts of the grid-side voltage respectively; I oR ,I oI Represent the real and imaginary parts of the output current respectively.

[0167] The corresponding electromechanical transient model is as follows Fig.10 As shown, Fig.10 Where ugR and ugI represent the real and imaginary parts of the grid voltage, respectively. gR , U gI , ioR, ioI represent the real and imaginary parts of the output current, respectively. oR ,I oI ,The grid-connected interface electromechanical transient model is constructed through multiplication boxes, addition boxes, and division boxes, and the converter output power is reflected in the system model in the form of node current injection.

[0168] The electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface are integrated to obtain a complete electromechanical transient model of the energy storage converter control system that can be embedded in the main interface of the PSASP software.

[0169] Through the user-defined interface in the PSASP software, the electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body, and the electromechanical transient model of the grid-connected interface are constructed. These models together form an electromechanical transient model of the energy storage converter control system that can be embedded in the main interface of PSASP. The model uses the node current injection method to reflect the change in converter output power at the access node, thereby visually demonstrating the quantitative impact of the energy storage converter on the grid-connected characteristics and power flow changes of the regional power grid. Using the final complete electromechanical transient model of the energy storage converter control system, the transient process of the energy storage converter system connected to the grid can be analyzed, thereby realizing the characteristic analysis and power flow calculation of the regional power grid system connected to the energy storage converter, providing technical support for the planning and design of the energy storage converter access to the regional power grid.

[0170] The present invention also provides a system for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system, comprising:

[0171] The grid-connected equivalent circuit construction module of the dual-droop control energy storage converter system applies the dual-droop control strategy to the energy storage converter control system, analyzes the regulation principle and grid-connected equivalent external characteristics of the energy storage converter control system, and constructs the grid-connected equivalent circuit of the dual-droop control energy storage converter system based on the analysis results;

[0172] The preliminary design and analysis module of the electromechanical transient model designs the structure of the energy storage converter system based on the grid-connected equivalent circuit of the constructed dual droop control energy storage converter system;

[0173] The sub-model construction module constructs the electromechanical transient model of the dual droop control part in the energy storage converter, the electromechanical transient model of the energy storage body, and the electromechanical transient model of the grid-connected interface according to the structure of the designed energy storage converter system;

[0174] The sub-model integration and electromechanical transient model construction module integrates the electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface to obtain a complete electromechanical transient model of the energy storage converter control system that can be embedded in the main interface of the PSASP software.

[0175] The present invention also provides an electronic device, the electronic device comprising: a processor and a memory;

[0176] The processor is used to execute the steps of the energy storage electromechanical transient model construction method by calling the program or instruction stored in the memory, and the steps include: applying the dual droop control strategy to the energy storage inverter control system, analyzing the regulation principle and grid-connected equivalent external characteristics of the energy storage inverter control system, and constructing the grid-connected equivalent circuit of the dual droop control energy storage inverter system based on the analysis results; designing the structure of the energy storage inverter system based on the constructed grid-connected equivalent circuit of the dual droop control energy storage inverter system; constructing the electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface in the energy storage inverter according to the designed structure of the energy storage inverter system; integrating the electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface to obtain a complete electromechanical transient model of the energy storage inverter control system that can be embedded in the main interface of the PSASP software.

[0177] The present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a program or instruction, and the program or instruction is a step of a computer executing the method for constructing an energy storage electromechanical transient model, which includes: applying a dual droop control strategy to an energy storage inverter control system, analyzing the regulation principle and grid-connected equivalent external characteristics of the energy storage inverter control system, and constructing a grid-connected equivalent circuit of a dual droop control energy storage inverter system based on the analysis results; designing the structure of the energy storage inverter system based on the constructed grid-connected equivalent circuit of the dual droop control energy storage inverter system; constructing an electromechanical transient model of a dual droop control part, an energy storage body electromechanical transient model, and a grid-connected interface electromechanical transient model in the energy storage inverter according to the designed structure of the energy storage inverter system; integrating the electromechanical transient model of the dual droop control part, the energy storage body electromechanical transient model, and the grid-connected interface electromechanical transient model to obtain a complete electromechanical transient model of the energy storage inverter control system that can be embedded in the main interface of the PSASP software.

[0178] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0179] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0180] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0181] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0182] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0183] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system, characterized in that: The following steps are involved: The dual droop control strategy is applied to the energy storage converter control system, and the regulation principle and grid-connected equivalent external characteristics of the energy storage converter control system are analyzed. Based on the analysis results, the grid-connected equivalent circuit of the dual droop control energy storage converter system is constructed. Based on the constructed grid-connected equivalent circuit of the dual droop control energy storage converter system, the structure of the energy storage converter system is designed; According to the structure of the designed energy storage converter system, the electromechanical transient model of the dual droop control part in the energy storage converter, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface are constructed; The electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface are integrated to obtain a complete electromechanical transient model of the energy storage converter control system that can be embedded in the main interface of the PSASP software.

2. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: The dual droop control strategy specifically includes a signal acquisition and power calculation module, an active power / frequency droop control, a reactive power / voltage droop control, a current inner loop controller, an output power calculation equation, a power differential equation and an SPWM module.

3. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: The energy storage converter control system includes an energy storage battery pack, a DC / AC converter, an energy management system, a control system and a filter; Among them, the energy storage battery pack is used for electric energy storage and electric energy absorption; DC / AC converters are used to convert direct current into alternating current suitable for grid connection; The energy management system EMS is used to monitor and control the status of battery cells, ensure the consistency between battery cells, and achieve energy distribution management goals; The control system is used to monitor the voltage and current signals of the power grid and send control signals to the converter to achieve the goal of stable grid-connected operation of the converter and the bidirectional flow of electric energy to meet the power control needs of the power grid; The filter is used to filter out harmonics in the grid-connected output voltage and current.

4. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: The double droop control strategy is applied to the energy storage converter control system, and the regulation principle and grid-connected equivalent external characteristics of the energy storage converter system are analyzed. Specifically: Active power / frequency droop control simulates the speed regulator of the synchronous machine, so that the active power and output frequency show droop control characteristics. The corresponding expression is as follows: f=f ref -k p (p o -p ref ) (1) Where, f is the converter droop control output frequency; f ref is the reference frequency; k p is the active frequency droop control coefficient; p o The active power output of the converter; p ref is the active power reference value; The reactive power / voltage droop control simulates the excitation regulator of the synchronous machine, so that the reactive power and AC output voltage present a droop control characteristic. The corresponding expression is as follows: u gd =u gref -k q (q o -q ref ) (2) In the formula, u gd is the d-axis component of the grid-side voltage output by the converter droop control; u gref is the grid-side voltage reference value; k q is the reactive voltage droop control coefficient; q o The reactive power output of the converter; q ref is the reactive power reference value.

5. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: Based on the analysis results, the grid-connected equivalent circuit of the dual droop control energy storage converter system is constructed, including: Calculate the current output by the energy storage converter to the grid, as shown in formula (3): In the formula, I o is the converter output current; U o ∠δ is the output voltage of the converter; U g ∠0 is the grid-side voltage; R f , L f are virtual resistance and virtual inductance respectively; j is the sign of the imaginary part; ω is the reference angular frequency; Let the virtual resistor R f is zero, making the equivalent impedance from the converter outlet to the grid side purely inductive, thereby realizing active and reactive power decoupling control, and the output apparent power can be deduced as: Where U g is the effective value of the grid-side voltage; U o is the effective value of the converter output voltage; is the reference value of the converter output current; U o ∠-δ is the conjugate of the converter output voltage; δ is the output reference phase angle; U g ∠0 is the grid-side voltage; L f are virtual inductance; P o , Q o Active power and reactive power reference value signals output by the converter; Further reverse calculation can be performed to obtain the output active power and reactive power of the converter: Where P o , Q o is the reference value signal of active power and reactive power output by the converter; δ is the output reference phase angle.

6. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: Based on the constructed grid-connected equivalent circuit of the dual droop control energy storage converter system, the structure of the energy storage converter system is designed as follows: The dual droop control energy storage converter system model is composed of a transformed power differential equation model and a dual droop control model; The electromechanical transient model of the energy storage converter system includes an energy storage battery pack body model, a DC / AC converter control model and a grid-connected interface model; The core component of the energy storage converter system is the DC / AC converter. When the control system changes the control signal, the frequency, amplitude and phase of the grid-connected output voltage can be controlled.

7. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 6, characterized in that: The control system includes system-level control and inner-loop control. The coordinated work of system-level control and inner-loop control realizes the precise control of active and reactive power of the power grid by the energy storage converter, specifically: System-level control is responsible for performing the main control tasks, including collecting the grid-side angular frequency ω from the power grid. g and grid-side voltage U g The collected signal is sent to the dual droop controller to calculate the active power P of the grid-connected output o and reactive power Q o Reference value; the energy storage battery pack obtains active power P o and reactive power Q o The reference value signal is then controlled through the energy management system to achieve battery SOC balance and consistency; The inner loop control is based on the power reference value signal provided by the system-level control, and is processed using proportional-integral PI control and decoupling control; the processed actual power signal is output to the grid-connected interface model, and the grid-connected interface model converts the output actual power signal into the d-axis and q-axis components of the grid-connected output current of the energy storage inverter to achieve node current injection.

8. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 7, characterized in that: The structure of the inner loop control is composed of an inner loop control model and a converter model, which includes a PI controller and a decoupling control link; Based on the inner loop control, the d-axis and q-axis currents can quickly track the control targets and achieve the decoupling control targets of active power and reactive power. Specifically: By removing the coupling link between the inner loop control and the converter model, further deduction can be made to obtain a control structure where the d and q axes are independent of each other, and the transfer functions of the d and q axes are deduced as follows: In the formula, i odref and i oqref is the reference value of the d-axis and q-axis components of the grid-connected output current; k pi and k ii is the proportional gain and integral gain of the PI controller; u gd and u gq is the reference value of the d-axis and q-axis components of the grid-side voltage; u zd and u zq The inner loop controls the output d-axis and q-axis components; L f is the virtual reactance; Using the zero-pole cancellation method, equation (7) is equivalent to a first-order inertia link, and the differential equation for power is: Where T1 and T2 are the actual power signal P and Q tracking reference value signal P respectively. o and Q o The inertia time constant.

9. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: Based on the energy storage converter with dual droop control, the electromechanical transient model of the dual droop control part in the energy storage converter is built through the user-defined interface in the PSASP software, specifically: The electromechanical transient model of the dual droop control part includes an active frequency droop control module, a reactive voltage droop control d-axis and q-axis module, an abc / dq forward transformation module, a PI control module, a current inner loop control module with inductor current decoupling, a dq / abc inverse transformation module, an output power calculation module, and a power differential equation module.

10. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: Considering the key parameters and constraints of the energy storage body, the electromechanical transient model of the energy storage body is constructed, specifically: The key parameters and constraints of the energy storage entity include: SOC calculation, capacity upper and lower limits, charge and discharge speed and power upper and lower limits, converter capacity upper and lower limits, efficiency limits and dead zone limits; Energy storage ontology model and constraints, specifically: Where: SOC is the real-time state of charge of the battery; SOC0 is the initial state of charge of the battery; T disch is the discharge time constant under rated power; P is the actual active power. When it is greater than zero, it indicates charging, and when it is less than zero, it indicates discharging, which is limited by the charging and discharging power; Q is the actual reactive power, which is limited by the converter capacity; SOC min , SOC max is the lower and upper limits of battery capacity; -P max , P max RD is the lower limit and upper limit of output active power; p , R.U. p The lower limit and upper limit of active power conversion rate; -Q max , Q max RD is the lower limit and upper limit of output reactive power; q , R.U. q is the lower limit and upper limit of reactive power conversion rate; η is the operating efficiency; f min 、f max is the lower limit and upper limit of the frequency; S 2 is the square of the output apparent power; P o It is the active power reference value signal output by the converter.

11. The method for constructing an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system according to claim 1, characterized in that: The construction of the grid-connected interface electromechanical transient model includes: The grid-connected interface model is used to convert the output power of the energy storage converter into current and inject it into the grid model, specifically: Convert the control output active power P and reactive power Q; Let the real and imaginary parts of the grid voltage be U gR , U gI , combined with I oR ,I oI Substituting into equation (4), we get equation (10), and based on P and Q, we can deduce I oR ,I oI The calculation expression of is shown in formula (11): Where P is the actual active power. When it is greater than zero, it indicates charging, and when it is less than zero, it indicates discharging. It is limited by the charging and discharging power. Q is the actual reactive power, which is limited by the converter capacity. U gR , U gI Respectively represent the real and imaginary parts of the grid-side voltage; I oR ,I oI Represent the real and imaginary parts of the output current respectively; The grid-connected interface electromechanical transient model is constructed through multiplication boxes, addition boxes, and division boxes, and the converter output power is reflected in the system model in the form of node current injection.

12. A system for building an energy storage electromechanical transient model for analyzing the characteristics of a synchronous control device grid-connected system, characterized in that: include: The dual droop control energy storage converter system model building module applies the dual droop control strategy to the energy storage converter control system, analyzes the regulation principle and grid-connected equivalent external characteristics of the energy storage converter control system, and builds a dual droop control energy storage converter system model based on the analysis results; The preliminary design and analysis module of the electromechanical transient model designs the structure of the energy storage converter system based on the constructed dual droop control energy storage converter system model; The sub-model construction module constructs the electromechanical transient model of the dual droop control part in the energy storage converter, the electromechanical transient model of the energy storage body, and the electromechanical transient model of the grid-connected interface according to the structure of the designed energy storage converter system; The sub-model integration and electromechanical transient model construction module integrates the electromechanical transient model of the dual droop control part, the electromechanical transient model of the energy storage body and the electromechanical transient model of the grid-connected interface to obtain a complete electromechanical transient model of the energy storage converter control system that can be embedded in the main interface of the PSASP software.

13. An electronic device, characterized in that: The electronic device comprises: Processor and memory; The processor is used to execute the steps of the energy storage electromechanical transient model construction method as described in any one of claims 1 to 11 by calling the program or instruction stored in the memory.

14. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program or instruction, and the program or instruction is a step for a computer to execute the method for constructing an energy storage electromechanical transient model as described in any one of claims 1 to 11.

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