Overload control protection method, system, equipment and medium for network construction type energy storage device

Abstract

The invention relates to a network construction type energy storage device overload control protection method, system, equipment and medium, and the method comprises the steps: switching an energy storage converter to an overload mode after receiving a short-time overload instruction of a power grid, and determining whether the current short-time power is within a preset maximum limit or not; if yes, the highest starting temperature of the energy storage converter and the battery in the corresponding overload scene is obtained, whether the real-time temperature is lower than the temperature or not is compared, and whether the SOC of the battery is appropriate or not is checked. And after the condition is met, injecting or absorbing power into the power grid according to the overload multiple. And monitoring the temperature and duration of the converter during overload, executing a protection strategy if the maximum allowable value or time is exceeded, otherwise, ending overload response, and returning to a normal mode. According to the method, the overall stability of the power grid and the operation safety of the energy storage equipment are improved, and especially in a weak power grid environment, frequency and voltage fluctuation caused by external disturbance is effectively dealt with.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-type energy storage, and in particular to an overload control protection method, system, equipment and medium for a grid-type energy storage device. Background Art

[0002] In the current power system, with the increase in the proportion of renewable energy generation, especially the widespread application of renewable energy such as wind power and photovoltaics, the power grid is facing many new challenges and demands. Traditional synchronous generators play a key role in stabilizing voltage and frequency in the power grid due to their inherent inertia and damping characteristics. However, renewable energy generation mostly relies on power electronic equipment such as converters to be connected to the power grid. These devices usually lack sufficient inertia and damping, which may have an adverse effect on the stability and reliability of the power system.

[0003] Higher requirements are placed on the environmental friendliness and efficient operation of power systems. This requires new power system solutions to adapt to a high proportion of renewable energy and power electronic equipment. Among them, grid-connected energy storage technology has emerged, providing new ideas and solutions to solve the problems existing in traditional power systems.

[0004] Grid-forming (GFM) converters can provide necessary grid support functions by simulating the characteristics of synchronous generators, such as providing virtual inertia and damping, and improving voltage and frequency support characteristics. This technology enables new energy generation equipment that originally did not have inertia to play a more active role in the grid and maintain the stability of the grid by providing necessary dynamic support.

[0005] However, grid-connected energy storage systems face a series of technical challenges in practical applications, especially in terms of short-term overload response, temperature rise control and protection strategies. These challenges require that related equipment not only be able to cope with grid demand under normal operating conditions, but also be able to safely and reliably handle sudden grid disturbances and overload conditions. For example, energy storage converters and batteries may suffer performance degradation or even damage due to excessive temperature rise when operating under overload. Summary of the invention

[0006] The present invention provides an overload control protection method, system, equipment and medium for a grid-type energy storage device, the purpose of which is to solve the problem of how to quickly respond to the disturbance of the frequency and its change rate of the power grid when the grid-type energy storage device actively supports the power grid to maintain the stable operation of the system, and to protect the energy storage battery and energy storage converter from short-term overload power response.

[0007] To achieve the above object, the first aspect of the present invention provides an overload control protection method for a grid-type energy storage device, comprising the following steps:

[0008] After receiving a short-term overload instruction from the power grid, the energy storage converter is switched from normal mode to overload mode, and the current overload scenario is determined;

[0009] Determine whether the short-term power of the current overload scenario is less than or equal to the preset maximum overload power limit;

[0010] If it is confirmed that the short-time power is within the allowable range, the maximum starting temperature of the energy storage converter and the energy storage battery under the overload scenario is obtained;

[0011] Compare the real-time temperatures of the energy storage converter and the energy storage battery to see if they are lower than their respective maximum starting temperatures, and check if the SOC of the energy storage battery is within the allowable range of the overload scenario;

[0012] If all the above conditions are met, the corresponding overload power is injected into or absorbed into the grid according to the overload multiple of the short-term overload instruction;

[0013] During the overload execution, monitor the real-time temperature and overload duration of the energy storage converter;

[0014] If the real-time temperature exceeds the maximum allowable value, or the overload duration exceeds the specified value, the corresponding protection strategy is adopted according to the current overload scenario;

[0015] If the real-time temperature does not exceed the maximum allowable value and the overload duration does not exceed the specified value, a short-term overload response is completed, the overload mode is turned off, and the energy storage converter is switched back to normal mode.

[0016] Furthermore, the short-term power in the current overload scenario needs to be less than or equal to three times the rated power of the energy storage converter.

[0017] Furthermore, the corresponding protection strategies adopted according to the current overload scenario include:

[0018] Overload scenario 1: power limiting operation to rated current and rated power;

[0019] Overload scenario 2: Block pulses and prohibit charging and discharging operations to the grid;

[0020] Overload scenario three: Disconnect the DC side contactor for shutdown protection.

[0021] Furthermore, after receiving a short-term overload instruction from the power grid, the energy storage inverter is switched from the normal mode to the overload mode, and the method for determining the current overload scenario includes: after receiving the short-term overload instruction from the power grid, the energy storage inverter receives and parses the short-term overload instruction, and after confirming that it is a valid short-term overload instruction, it automatically switches from the normal mode to the overload mode, and by analyzing the received short-term overload instruction, determines that the current overload scenario is any one of overload scenario one, overload scenario two or overload scenario three.

[0022] Further, according to the overload multiple of the short-term overload instruction, injecting or absorbing the corresponding overload power into the power grid includes: calculating the overload power according to the overload multiple multiplied by the rated power of the energy storage converter.

[0023] Furthermore, the method for obtaining the maximum starting temperature includes predetermining it through type testing of the energy storage inverter and the energy storage battery.

[0024] To achieve the above-mentioned purpose, the second aspect of the present invention provides an overload control and protection system for a grid-type energy storage device. The system comprises:

[0025] Energy storage unit, which includes energy storage battery, BMS and energy storage converter;

[0026] The acquisition server is configured with a data interface for receiving real-time data from the BMS and energy storage converter of the energy storage unit, wherein the real-time data includes the SOC value, current, voltage and temperature information of the energy storage battery, and performing preliminary processing on the real-time data;

[0027] The data server is connected to the acquisition server through the network and is used to store and manage the real-time data transmitted from the acquisition server;

[0028] The timing server is connected to the energy storage coordination control system through the network, and is responsible for receiving Beidou and GPS satellite timing signals and providing timing signals;

[0029] The energy storage coordination control system is connected to the collection server and data server through the network, and is equipped with a sampling module for the grid-connected point of the cooperative control equipment, a real-time monitoring module for the energy storage battery and the energy storage converter, a network-type cooperative control power algorithm module, an overload scenario and protection setting module, an energy storage device power limit output module, a pulse blocking and shutdown command module. It calculates and issues overload power commands based on the received real-time data, and sends them to the energy storage converter through the GOOSE communication protocol.

[0030] The monitoring server is connected to the energy storage coordination control system through the network, and is used for graphic and report display, event recording and alarm status display and query, while displaying the overload status and protection measures of the energy storage system.

[0031] Furthermore, the grid-connected point sampling module of the cooperative control device is responsible for collecting the current parameters, voltage parameters, power parameters, and frequency parameters of the grid-connected point, and transmitting the current parameters, voltage parameters, power parameters, and frequency parameters to the networking cooperative control power algorithm module in real time for analysis and processing;

[0032] The energy storage battery and energy storage converter real-time monitoring module receives the real-time data of the energy storage battery and the energy storage converter transmitted from the acquisition server, and monitors the real-time working status of the energy storage unit based on the real-time data to adjust the overload response in real time;

[0033] The grid-forming cooperative power control algorithm module calculates the required additional power according to the frequency and frequency change rate of the power grid and the received grid connection point parameters, and uniformly sends the overload power instruction to the energy storage converter through the GOOSE communication protocol;

[0034] The overload scenario and protection setting module and the energy storage device power output limiting module, pulse blocking and shutdown instruction module set different overload scenarios and corresponding protection strategies according to the size of the additional power instruction. The protection strategy includes power output limiting, pulse blocking, charging and discharging prohibition and shutdown instructions;

[0035] The monitoring server is used to display relevant graphics, alarm signals and event records to the operator based on the alarm and operation status information received from the energy storage coordinated control system.

[0036] To achieve the above-mentioned purpose, the third aspect of the present invention provides an electronic device, including a processor and a memory, wherein the processor is used to implement the steps of the overload control protection method of the grid-type energy storage device when executing a computer program stored in the memory.

[0037] To achieve the above-mentioned purpose, the fourth aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the overload control protection method of the grid-type energy storage device are executed.

[0038] Beneficial effects of the present invention:

[0039] Compared with the prior art, the present invention provides a method, system, device and medium for overload control and protection of a grid-connected energy storage device. By quickly collecting the frequency and voltage of the grid connection point, the actual power increase instruction is calculated, and based on the virtual synchronous machine control technology and the GOOSE communication control protocol, the output consistency of multiple energy storage converters and the rapid support of the frequency are achieved; and by comprehensively considering whether the overload start-up temperature of the energy storage converter, the overload start-up temperature of the energy storage battery and the SOC of the energy storage battery are over the limit, whether the energy storage system has the short-term overload capacity is identified, and preventive protection of the energy storage battery and the converter is achieved; by real-time monitoring whether the converter temperature and overload time are over the limit, based on the three constructed overload scenarios, responding to the short-term overload instruction of the power grid, a three-level protection strategy for the cooperation of the BMS and the energy storage converter is proposed, and the energy storage converter is limited in power, pulsed and prohibited from charging and discharging, and shut down and disconnected from the DC side contactor, so as to achieve real-time protection of the energy storage battery and the converter during short-term overload operation, improve the system reliability and life, reduce safety hazards, and support the stable operation of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0041] Figure 1 It is a framework diagram of an overload control and protection system for a grid-type energy storage device disclosed in an embodiment of the present invention.

[0042] Figure 2 It is a flow chart of an overload control protection method for a grid-type energy storage device disclosed in an embodiment of the present invention.

[0043] Figure 3 It is a two-time response diagram of a short-time power overload instruction disclosed in an embodiment of the present invention.

[0044] Figure 4 It is an output power diagram of a converter when the overload time exceeds a limit under different overload scenarios disclosed in an embodiment of the present invention.

[0045] Figure numerals: 1. Energy storage unit; 2. Timing server; 3. Workstation; 4. Data server; 5. Collection server; 6. Energy storage coordination control system. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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 only 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 should fall within the scope of protection of the present invention.

[0047] The present invention provides an overload control and protection system for a grid-type energy storage device. Figure 1 The topology diagram of the overload control and protection system for the networked energy storage device is mainly composed of: energy storage unit 1, monitoring server, time synchronization server 2, workstation 3, data server 4, acquisition server 5 and energy storage coordination control system 6.

[0048] Among them, the energy storage unit 1 mainly includes energy storage batteries, BMS, energy storage inverters and isolated step-up transformers, which are connected to the collector and connected to the power grid through the main transformer; the timing server 2 is connected to the energy storage coordination control system 6 through the network, responsible for receiving Beidou and GPS satellite timing signals, providing the system timing signals, and ensuring high-precision and high-stability time reliability; the workstation 3 is used for graphic and report display, event recording and alarm status display and query, and displays, alarms and records short-term overload status; the data server is connected to the acquisition server 5 through the network, which is used for data storage and read-write center; the acquisition server 5 is used for data collection, analysis and processing of all BMS and energy storage inverters of the subordinate energy storage unit 1; the energy storage coordination control system 6 is the core of the network-type control, and is configured with dual-machine redundancy to coordinate the overload power distribution of the networked energy storage unit.

[0049] In order to achieve rapid response to short-term power overload, the energy storage coordination control system 6 proposed in the present invention includes the following modules: a sampling module for the grid-connected point of the cooperative control equipment, a real-time monitoring module for the energy storage battery and the energy storage converter, a network-type cooperative control power algorithm module, an overload scenario and protection setting module, an energy storage device power limiting output module, and a pulse blocking and shutdown instruction module.

[0050] Coordination control equipment grid connection point sampling module: The coordination controller integrates the function of fast frequency device, which can collect line or bus current, voltage, power, frequency, etc., and can meet the high-precision and high-speed sampling control requirements of short-term overload for grid support; Energy storage battery and energy storage inverter real-time monitoring module: By obtaining the data of subordinate energy storage unit BMS and PCS collected by the acquisition server on the data network, including the real-time temperature of the energy storage battery, SOC value and real-time temperature of the energy storage inverter; Networking cooperative control power algorithm module: It integrates the networking control strategy of the virtual synchronous generator. It can determine the power to be increased according to the grid frequency and frequency change rate. When crossing the dead zone range, it can determine the power to be increased according to the deviation between the target power and the actual power, and send it to the energy storage inverter through the GOOSE communication protocol. Especially in the case of multiple energy storage inverters, it can improve the accuracy and consistency of short-term overload response, and realize fast and stable support for the power grid.

[0051] Specifically, the grid-connected point sampling module of the cooperative control device is responsible for collecting the current parameters, voltage parameters, power parameters, and frequency parameters of the grid-connected point, and transmitting the current parameters, voltage parameters, power parameters, and frequency parameters to the networking cooperative control power algorithm module in real time for analysis and processing;

[0052] The energy storage battery and energy storage converter real-time monitoring module receives the real-time data of the energy storage battery and the energy storage converter transmitted from the acquisition server 5, and monitors the real-time working state of the energy storage unit 1 based on the real-time data to adjust the overload response in real time;

[0053] The grid-forming cooperative power control algorithm module calculates the required additional power according to the frequency and frequency change rate of the power grid and the received grid connection point parameters, and uniformly sends the overload power instruction to the energy storage converter through the GOOSE communication protocol;

[0054] The overload scenario and protection setting module and the energy storage device power output limiting module, pulse blocking and shutdown instruction module set different overload scenarios and corresponding protection strategies according to the size of the additional power instruction. The protection strategy includes power output limiting, pulse blocking, charging and discharging prohibition and shutdown instructions;

[0055] The monitoring server is used to display relevant graphics, alarm signals and event records to the operator based on the alarm and operation status information received from the energy storage coordination control system 6.

[0056] Overload scenario and protection setting module: According to the size of the additional power instruction, the overload scenario is judged, which is divided into overload scenario 1: the energy storage unit executes a 1.2-fold short-term power overload response instruction; overload scenario 2: the energy storage unit executes a 1.5-fold short-term power overload response instruction; overload scenario 3: the energy storage unit executes a 3.0-fold short-term power overload response instruction, and at the same time sets the protection threshold before responding to the overload instruction and the real-time overload response; energy storage unit power output limit module, pulse blocking and shutdown instruction module: according to the overload scenario and protection threshold, the energy storage unit responds to the overload instruction and performs power output limit, pulse blocking, charging and discharging prohibition, and shutdown protection strategies respectively. The battery management system BMS cooperates with the energy storage inverter, and the energy storage inverter responds to the BMS status through CAN communication to achieve protection. The specific execution adopts a three-level protection strategy and is equipped with a hysteresis mechanism: three-level protection fault alarm, the second-level protection fault sends the inverter charging and discharging prohibition instruction, the first-level protection fault notifies the inverter to shut down, the normally closed dry node is tripped, and the energy storage DC side circuit is disconnected.

[0057] According to an embodiment of the present invention, it should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the following production method, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0058] like Figure 2 As shown, the present invention also provides an overload control protection method for a grid-type energy storage device. When a disturbance occurs in the power grid and causes a change in the grid frequency, the high-precision fast frequency acquisition function of the coordinated control device is used to collect parameters such as the frequency, voltage, and current of the grid connection point, receive real-time data of the energy storage unit BMS and PCS under the acquisition server, and use a grid-type cooperative power control algorithm to uniformly issue an overload power instruction to the energy storage converter in response to the overload. Different protection strategies are set for different overload scenarios to protect the grid-type energy storage device. The specific method includes the following steps:

[0059] Step S100: after receiving a short-term overload instruction from the power grid, switch the energy storage converter from the normal mode to the overload mode, and determine the current overload scenario;

[0060] Step S200, determining whether the short-term power of the current overload scenario is less than or equal to the preset maximum overload power limit;

[0061] Step S300: If it is confirmed that the short-time power is within the allowable range, the maximum starting temperature of the energy storage converter and the energy storage battery in the overload scenario is obtained;

[0062] Step S400, comparing whether the real-time temperatures of the energy storage converter and the energy storage battery are lower than their respective maximum starting temperatures, and checking whether the SOC of the energy storage battery is within the allowable range of the overload scenario;

[0063] Step S500: If all the above conditions are met, inject or absorb corresponding overload power into the power grid according to the overload multiple of the short-term overload instruction;

[0064] Step S600: During the overload execution period, monitor the real-time temperature and overload duration of the energy storage converter;

[0065] Step S700: If the real-time temperature exceeds the maximum allowable value, or the overload duration exceeds the specified value, a corresponding protection strategy is adopted according to the current overload scenario;

[0066] Step S800: If the real-time temperature does not exceed the maximum allowable value and the overload duration does not exceed the specified value, a short-term overload response is completed, the overload mode is turned off, and the energy storage converter is switched back to the normal mode.

[0067] In this embodiment, as described in the above steps S100 to S800, when the frequency of the large power grid changes due to external disturbances or load changes, and the grid-connected energy storage converter needs to instantly increase power to support the grid, the grid-connected energy storage converter receives a short-term overload instruction and switches from normal mode to overload mode. According to the size of the overload power instruction, the current overload scenario is identified and the response is ≤3P N Overload power command.

[0068] The first thing to consider is the temperature rise constraint of the energy storage converter itself. When a short-term overload is executed, the IGBT device in the energy storage converter will flow through a short-term large current, and its switching loss and conduction loss will increase, which will cause heat accumulation. When the temperature rise reaches a certain level, the device will be forced to derate, affecting the stable operation of the system. PCS is the real-time temperature of the energy storage converter detected, T PCS_MAX It is the maximum temperature allowed during the operation of the energy storage converter. If the detected real-time temperature is greater than its maximum value, the energy storage converter will shut down immediately. In the current overload scenario, it should be pointed out that before the energy storage converter responds to the overload power command, it is necessary to compare the real-time temperature T of the energy storage converter. PCS The maximum temperature T allowed by the preset overload scenario PCS_i_MAX , where T PCS_i_MAX The temperature rise of IGBT device ΔT when the converter performs the corresponding overload multiple obtained in advance PCS and not exceeding T PCS_MAX , that is, T PCS_i_MAX +ΔT PCS ≤T PCS_MAX , which can be obtained through type testing of the energy storage converter.

[0069] The second thing to consider is the temperature rise constraint of the energy storage battery. When a short-term overload is executed, the instantaneous discharge rate of the lithium-ion battery increases. The large discharge current will cause a sharp increase in the heat generated in the battery cell, especially when responding to short-term overload conditions at a high frequency. This will not only affect the battery activity and cause lithium precipitation, but also seriously affect the battery life and bring safety hazards such as fire. Battery is the real-time temperature of the energy storage battery, T Battery_MAX is the maximum temperature allowed. If the detected real-time temperature is greater than its maximum value, the energy storage converter will immediately shut down and disconnect the DC side circuit. In the current overload scenario, it should be pointed out that before the energy storage converter responds to the overload power command, it is necessary to compare the real-time temperature T of the energy storage battery. Battery The maximum temperature T allowed by the preset overload scenario Battery_i_MAX , where T Battery_i_MAX When the energy storage battery is charged and discharged with the corresponding overload multiples, T Battery_i_MAX and the temperature rise of the energy storage battery ΔT Battery and not exceeding T Battery_MAX , that is, TBattery_i_MAX +ΔT Battery ≤T Battery_MAX , which can be obtained through type testing of energy storage batteries.

[0070] Before the energy storage inverter executes the overload instruction again, it is determined whether the energy storage inverter response overload start temperature, the energy storage battery response overload start temperature and the energy storage battery SOC are out of limit. That is, before the energy storage inverter executes a short-term power overload, it is identified whether the energy storage inverter temperature rise, energy storage battery temperature rise and SOC constraints are met, thereby achieving preventive protection for the energy storage battery and the inverter.

[0071] Finally, before the energy storage converter responds to the overload instruction, the energy storage battery SOC constraint needs to be pointed out: when the energy storage converter performs 1.2 times, 1.5 times and 3 times short-term overload discharge output, the upper limit of the energy storage battery discharge is 100%, but the lower limit of the energy storage battery discharge, especially considering the end effect, needs to be set to ensure that the active power can be continuously output; when the energy storage converter performs 1.2 times, 1.5 times and 3 times short-term overload charging, considering the end effect, the lower limit of the energy storage battery charge is 10%, but the upper limit of the energy storage battery charge needs to be set to avoid overcharging in consideration of high-power charging; combined with actual engineering experience, a SOC threshold under short-term overload protection conditions is defined, as shown in Table 1:

[0072] Table 1 Short-time overload energy storage battery SOC threshold

[0073] Serial number Working conditions Charging SOC threshold allocation Discharge SOC threshold allocation 1 <![CDATA[1.2P N Overload]]> 10％-90％ 10％-100％ 2 <![CDATA[1.5P N Overload]]> 10％-85％ 20％-100％ 3 <![CDATA[3.0P N Overload]]> 10％-75％ 35％-100％

[0074] When the temperature and SOC constraints of the energy storage converter and the DC side energy storage battery are met in the current overload scenario, the energy storage converter injects or absorbs the overload power k1*P into the grid according to the received charge and discharge instructions. N , P N is the rated power of the energy storage converter, and k1 is the overload multiple.

[0075] The energy storage inverter executes the overload instruction and performs short-term overload power output. By real-time monitoring whether the temperature of the energy storage inverter exceeds the limit and whether the overload time exceeds the specified maximum allowable time, when the temperature rise of the inverter exceeds the limit and the overload time exceeds the limit, the overload scenario protection action is executed to achieve operation protection of the energy storage battery and inverter during short-term overload.

[0076] For overload scenario 1, respond to the grid power requirements according to the issued overload multiple and time constraints to actively support the grid. run >t set_i , output an alarm signal, and at the same time limit the power of the converter to rated current and rated power, thereby protecting the energy storage battery and energy storage converter.

[0077] For overload scenario 2, the grid power requirement is responded to according to the issued overload multiple and time constraints to actively support the grid. When the operation time is t run >t set_i , output a signal that prohibits charging and discharging, and at the same time, the energy storage converter seals the pulse, prohibiting charging and discharging to the grid, thereby protecting the energy storage battery and converter.

[0078] For overload scenario 3, the grid is actively supported according to the overload multiple and time constraints issued by the grid power response. run >t set_i , output the shutdown signal and disconnect the dry node signal at the same time, the energy storage converter shuts down and disconnects the DC side contactor to protect the energy storage battery and converter.

[0079] Among them, t run is the overload operation time, t set_i is the maximum overload operation time of the energy storage converter under the corresponding overload scenario; and, t set_i According to the Grid-connected Energy Storage System Grid Test Specification, the energy storage converter responds to 1.2P N , 1.5P N and 3P N When the power is increased, the overload time is set to 120s, 60s and 10s respectively, which is the maximum short-term overload time corresponding to the overload multiple operation.

[0080] For the overload scenario status judgment condition, the actual software logic program judgment is not necessarily directly 1.2P N , 1.5P N or 3P N , which may be a certain intermediate overload multiple situation, is defined in combination with the cluster current value collected by the BMS and the protection execution strategy, as shown in Table 2.

[0081] Table 2 Overload scenario status judgment conditions

[0082] Serial number Overload scenario Judgment conditions Protection strategy 1 Overload scenario 1 <![CDATA[1.1I N <I≤1.2I N ]]> Three-level protection strategy 2 Overload scenario 2 <![CDATA[1.2I N <I≤1.5I N ]]> Secondary protection strategy 3 Overload scenario 3 <![CDATA[1.5I N <I≤3.0I N ]]> Primary protection strategy

[0083] The priority of the protection strategy is: first-level protection strategy > second-level protection strategy > third-level protection strategy.

[0084] The specific technical solutions of the present invention are as follows:

[0085] Step S1: The grid-connected energy storage converter receives the transmitted short-term overload instruction, switches from normal mode to overload mode, and identifies the current overload scenario. The current short-term overload response power is ≤3P N If yes, go to step S2, otherwise go to step S7;

[0086] Step S2: When the energy storage system responds to the grid overload instruction, the maximum starting temperature T corresponding to the energy storage converter and the energy storage battery in the current overload scenario is obtained. PCS_i_MAX , T Battery_i_MAX , then go to step S3;

[0087] Step S3: Determine whether the energy storage converter response overload start temperature is appropriate. If the real-time temperature T PCS Less than the maximum starting temperature T of the energy storage converter under the corresponding overload scenario i PCS_i_MAX If yes, go to step S4, otherwise go to step S7;

[0088] Step S4: Determine whether the energy storage battery overload response start temperature is appropriate. If the energy storage battery real-time temperature T Battery Less than the maximum starting temperature T of the energy storage battery under the corresponding overload scenario i Battery_i_MAX If yes, go to step S5, otherwise go to step S7;

[0089] Step S5: Determine whether the energy storage battery SOC exceeds the SOC limit i_min <SOC i <SOC i_max If yes, go to step S6, otherwise go to step S7;

[0090] Step S6: The converter executes the overload instruction and injects or absorbs the overload power k1*P into the grid according to the charge and discharge instructions. N , then go to step S8;

[0091] Step S7: The energy storage converter does not have the short-term overload capacity for the overload scenario, and is limited to the rated current and power output;

[0092] Step S8: Real-time detection of whether the temperature of the energy storage converter exceeds the limit T PCS >T PCS_MAX If the limit is not exceeded, go to step S9; if the limit is exceeded, go to step S13;

[0093] Step S9: Real-time detection of whether the overload time exceeds the specified time t run >t set_i If yes, go to step S10, otherwise go to step S14;

[0094] Step S10: according to the energy storage converter overload scenario i, go to steps S11, S12 and S13 respectively;

[0095] Step S11: for overload scenario 1, an alarm is issued and a power limiting signal is issued at the same time, the energy storage converter is limited to the rated current and rated power output, and then the process goes to step S14;

[0096] Step S12: For overload scenario 2, the BMS outputs a charge-discharge prohibition signal to the energy storage converter, and the energy storage converter blocks pulses, prohibiting charging and discharging to the grid, and then proceeds to step S14;

[0097] Step S13: For overload scenario three, output a shutdown signal to the energy storage converter, the normally closed dry node is tripped, the energy storage converter disconnects the DC contactor, and shuts down to protect the energy storage battery and converter from overload, and then goes to step S14;

[0098] Step S14: After a short-term overload is completed, the overload mode is turned off, the mode is switched to the normal mode, and the number of short-term overloads in each scenario is counted.

[0099] like Figure 3 As shown, two short 3P N For example, the energy storage converter follows the 3P N After responding to the grid overload command for 8s, the rated power P N After 2 minutes, when the temperature of the energy storage converter, the temperature of the energy storage battery and the SOC do not exceed the limit, it responds to the 3P N The short-time overload command is 6s, which realizes two responses of the same overload command with different overload times, actively supporting the grid frequency.

[0100] like Figure 4 As shown in the figure, the power changes and protection conditions of the grid-connected converter in response to short-term overload in the above-mentioned overload scenarios are compared. Overload scenario 1: The energy storage converter is operated at 1.2P N Short-term overload power operation, current limiting is performed after more than 2 minutes, and the active power is limited to the rated power P N Output; Overload scenario 2: Energy storage converter at 1.5P N Short-term overload power operation, after more than 1 minute, a charge and discharge prohibition instruction is issued, and the active power of the converter is reduced to zero. Overload scenario three: Energy storage converter 3P N In case of short-term overload operation, the machine will shut down after more than 10 seconds and the active power of the converter will drop to zero.

[0101] The present invention mainly aims at the adverse effects on the safe operation of energy storage batteries and converters caused by the grid-building energy storage system when maintaining the stability of the power system and responding to the short-term overload output of the power grid. The present invention realizes rapid active support of the power grid through the grid-building energy storage overload power coordination control algorithm, and can identify whether the energy storage system has the grid-building overload capacity before the short-term overload. At the same time, a three-level protection strategy is adopted in the short-term overload, which can realize real-time protection of energy storage batteries and converters, improve the system reliability and life, reduce the safety hazards of battery thermal runaway and energy storage converter explosion caused by short-term overload, and effectively support the power grid.

[0102] According to another aspect of an embodiment of the present application, there is further provided an electronic device, including a processor and a memory, wherein the processor is configured to implement the steps of the method when executing a computer program stored in the memory.

[0103] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0104] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0105] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0106] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0107] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for overload control and protection of a grid-type energy storage device, characterized in that: The steps include: After receiving a short-term overload instruction from the power grid, the energy storage converter is switched from normal mode to overload mode, and the current overload scenario is determined; Determine whether the short-term power of the current overload scenario is less than or equal to the preset maximum overload power limit; If it is confirmed that the short-time power is within the allowable range, the maximum starting temperature of the energy storage converter and the energy storage battery under the overload scenario is obtained; Compare the real-time temperatures of the energy storage converter and the energy storage battery to see if they are lower than their respective maximum starting temperatures, and check if the SOC of the energy storage battery is within the allowable range of the overload scenario; If all the above conditions are met, the corresponding overload power is injected into or absorbed into the grid according to the overload multiple of the short-term overload instruction; During the overload execution, monitor the real-time temperature and overload duration of the energy storage converter; If the real-time temperature exceeds the maximum allowable value, or the overload duration exceeds the specified value, the corresponding protection strategy is adopted according to the current overload scenario; If the real-time temperature does not exceed the maximum allowable value and the overload duration does not exceed the specified value, a short-term overload response is completed, the overload mode is turned off, and the energy storage converter is switched back to normal mode.

2. The overload control and protection method for a grid-type energy storage device according to claim 1, characterized in that: The short-term power in the current overload scenario needs to be less than or equal to three times the rated power of the energy storage converter.

3. The overload control and protection method for a grid-type energy storage device according to claim 1, characterized in that: The corresponding protection strategies adopted according to the current overload scenario include: Overload scenario 1: power limiting operation to rated current and rated power; Overload scenario 2: Block pulses and prohibit charging and discharging operations to the grid; Overload scenario three: Disconnect the DC side contactor for shutdown protection.

4. The overload control and protection method for a grid-type energy storage device according to claim 3, characterized in that: After receiving a short-term overload instruction from the power grid, the energy storage converter is switched from the normal mode to the overload mode, and the method for determining the current overload scenario includes: after receiving the short-term overload instruction from the power grid, the energy storage converter receives and parses the short-term overload instruction, and after confirming that it is a valid short-term overload instruction, it automatically switches from the normal mode to the overload mode, and by analyzing the received short-term overload instruction, determines that the current overload scenario is any one of overload scenario one, overload scenario two or overload scenario three.

5. The overload control and protection method for a grid-type energy storage device according to claim 1, characterized in that: Injecting or absorbing corresponding overload power into the power grid according to the overload multiple of the short-time overload instruction includes: calculating the overload power according to the overload multiple multiplied by the rated power of the energy storage converter.

6. The overload control and protection method for a grid-type energy storage device according to claim 1, characterized in that: The method for obtaining the maximum starting temperature includes predetermining the maximum starting temperature through type tests of the energy storage converter and the energy storage battery.

7. A grid-type energy storage device overload control protection system, characterized in that: include: Energy storage unit, which includes energy storage battery, BMS and energy storage converter; The acquisition server is configured with a data interface for receiving real-time data from the BMS and energy storage converter of the energy storage unit, wherein the real-time data includes the SOC value, current, voltage and temperature information of the energy storage battery, and performing preliminary processing on the real-time data; The data server is connected to the acquisition server through the network and is used to store and manage the real-time data transmitted from the acquisition server; The timing server is connected to the energy storage coordination control system through the network, and is responsible for receiving Beidou and GPS satellite timing signals and providing timing signals; The energy storage coordination control system is connected to the collection server and data server through the network, and is equipped with a sampling module for the grid-connected point of the cooperative control equipment, a real-time monitoring module for the energy storage battery and the energy storage converter, a network-type cooperative control power algorithm module, an overload scenario and protection setting module, an energy storage device power limit output module, a pulse blocking and shutdown command module. It calculates and issues overload power commands based on the received real-time data, and sends them to the energy storage converter through the GOOSE communication protocol. The monitoring server is connected to the energy storage coordination control system through the network, and is used for graphic and report display, event recording and alarm status display and query, while displaying the overload status and protection measures of the energy storage system.

8. The overload control and protection system for a grid-type energy storage device according to claim 7, characterized in that: in: The grid-connected point sampling module of the cooperative control equipment is responsible for collecting the current parameters, voltage parameters, power parameters and frequency parameters of the grid-connected point, and transmitting the current parameters, voltage parameters, power parameters and frequency parameters to the grid-connected cooperative control power algorithm module in real time for analysis and processing; The energy storage battery and energy storage converter real-time monitoring module receives the real-time data of the energy storage battery and the energy storage converter transmitted from the acquisition server, and monitors the real-time working status of the energy storage unit based on the real-time data to adjust the overload response in real time; The grid-forming cooperative power control algorithm module calculates the required additional power according to the frequency and frequency change rate of the power grid and the received grid connection point parameters, and uniformly sends the overload power instruction to the energy storage converter through the GOOSE communication protocol; The overload scenario and protection setting module and the energy storage device power output limiting module, pulse blocking and shutdown instruction module set different overload scenarios and corresponding protection strategies according to the size of the additional power instruction. The protection strategy includes power output limiting, pulse blocking, charging and discharging prohibition and shutdown instructions; The monitoring server is used to display relevant graphics, alarm signals and event records to the operator based on the alarm and operation status information received from the energy storage coordinated control system.

9. An electronic device, characterized in that: It comprises a processor and a memory, wherein the processor is used to implement the steps of the overload control protection method of the grid-type energy storage device as claimed in any one of claims 1 to 6 when executing the computer program stored in the memory.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the overload control protection method for a grid-type energy storage device according to any one of claims 1 to 6 are executed.

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