High-voltage direct-hanging energy storage equipment energy storage submodule test system and test method

Abstract

The application provides a high-voltage direct-hanging energy storage equipment energy storage submodule test system and test method, comprising: a current generator, which generates test current using a cascaded full-bridge structure and can reduce the harmonic content of the output voltage of the current generator based on carrier phase shift or carrier layering modulation; an energy storage submodule to be tested; a current controller for controlling the current generator to adjust the test current; a submodule controller for controlling the energy storage submodule to be tested to adjust the state of charge and voltage of the submodule; and an energy storage system parameter model for outputting reference signals for current control and state of charge control to the current controller and the submodule controller, respectively. The application can test the energy storage submodule in accordance with the actual system operation condition without building a complete energy storage system and effectively reduces the requirements of the test circuit for the switching frequency of the power semiconductor device, the filter and the direct current power supply.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of energy storage, and particularly relates to an energy storage submodule test system and method for high-voltage direct-hanging energy storage equipment. BACKGROUND

[0002] With the rapid development of renewable energy generation represented by wind power generation and photovoltaic power generation, the volatility, randomness and uncertainty of new energy power generation pose great challenges to the safe and stable operation of power grids. In order to solve this problem, energy storage technology is applied to the power transmission and distribution link to smooth new energy power generation through rapid regulation of power grid voltage and power, thereby realizing the optimal management of power quality. High-voltage direct-hanging large-capacity energy storage systems realize the dispersed placement and management of a large number of batteries by connecting the battery clusters in parallel to the DC capacitor of a chain converter, and have realized relatively mature engineering demonstration applications in China.

[0003] A high-voltage direct-hanging large-capacity energy storage system is generally composed of three-phase cascaded energy storage units and contains a large number of energy storage submodules. For example, the 2MW / 10kV demonstration system of Shenzhen Baqing Energy Storage Station is composed of 3 phases x 20 chain links, i.e. 60 submodules. How to efficiently, accurately and quickly realize the test of the submodules is a difficulty in improving the reliability of the energy storage system.

[0004] For example, through retrieval, it is found that:

[0005] A Chinese utility model patent with the patent number CN209311592U discloses a kind of high-voltage direct-hanging energy storage converter modular test platform and test circuit, which uses three-phase converter and three-phase selector switch, and needs to build complete energy storage system for testing;A Chinese invention patent with the patent number CN115112976A discloses a kind of test system and control method suitable for high-voltage cascaded energy storage converter, which simulates the working characteristics of battery cluster through isolated DC / DC power module, and does not control test current.

[0006] The test system based on working condition simulation can simulate the actual voltage and current of the submodules through a simplified circuit, but since the to-be-tested energy storage submodule usually adopts carrier phase-shifted sinusoidal pulse width modulation in the actual energy storage system, the switching frequency of the single submodule is low, which can cause the working condition simulation test system to have high voltage level, many submodules, increased current ripple, deviate from the actual system current, affect the test precision, and increase the test cost. SUMMARY

[0007] The application aims to provide an energy storage submodule test system and method for high-voltage direct-hanging energy storage equipment, so as to achieve the technical effects of simulating actual operating conditions and performing testing without building a complete system, improving test precision, reducing test cost, and reducing test current ripple.

[0008] According to one aspect of the present application, a high-voltage direct-hanging energy storage sub-module test system is provided, comprising:

[0009] a current generator for generating test current, the current generator comprising at least a cascaded full-bridge circuit and a constant-voltage DC source;

[0010] a to-be-tested energy storage sub-module, the to-be-tested energy storage sub-module comprising at least an H-bridge circuit and a battery cluster, the test system achieving testing by applying current and control signals conforming to actual operating conditions to the to-be-tested energy storage sub-module;

[0011] The test system further comprises:

[0012] a current controller for receiving test current sampling signals output by the current generator and port voltage signals of the to-be-tested energy storage sub-module, and generating control signals of the current generator, so that the output current of the current generator is the same as the actual operating current of the actual energy storage sub-module;

[0013] a sub-module controller for receiving state-of-charge estimation signals output by the to-be-tested energy storage sub-module, generating control signals of the to-be-tested energy storage sub-module, and adjusting the voltage and battery cluster state-of-charge of the to-be-tested energy storage sub-module to be the same as the actual operating voltage and battery cluster state-of-charge of the actual energy storage sub-module.

[0014] Optionally, the cascaded full-bridge circuit of the current generator comprises at least n,

[0015] The DC side of the cascaded full-bridge circuit is connected to n DC voltage sources with output voltage V s , or to n DC ends of a multi-winding transformer after rectification.

[0016] Optionally, the cascaded full-bridge circuit in the current generator adopts carrier phase-shift modulation or carrier layer superposition modulation,

[0017] When carrier phase-shift modulation is adopted, n triangular carriers with adjacent phase angle differences of 2π / n and ranges between -1 and 1 are adopted;

[0018] When carrier layer superposition modulation is adopted, n triangular carriers with the same phase angle and adjacent amplitude differences of 2 / n and ranges between -1 and 1 are adopted.

[0019] Optionally, the maximum output voltage of the current generator is equal to the product of the number of cascaded full-bridge circuits of the current generator and the power supply voltage of the current generator, and is not less than the sum of the filter inductance voltage of the current generator and the port voltage of the to-be-tested energy storage sub-module,

[0020] The maximum port voltage of the to-be-tested energy storage submodule is represented as the sum of the DC component of the parallel capacitor voltage of the to-be-tested energy storage submodule and the maximum voltage ripple.

[0021] Optionally, the test system further comprises:

[0022] An energy storage system parameter model, configured to output a corresponding bridge arm current reference signal to the current controller according to system operation parameters and specifications of the energy storage submodule;

[0023] and further configured to output a state of charge reference signal and a modulation voltage reference signal to the submodule controller.

[0024] Optionally, the current controller is configured to receive the bridge arm current reference signal calculated by the energy storage system parameter model, the test current signal sampled, and the port voltage signal of the to-be-tested energy storage submodule, obtain a modulation voltage through proportional-integral-resonant control, generate a switching signal, and output the switching signal to the cascaded full-bridge circuit in the current generator.

[0025] Optionally, the submodule controller is configured to receive the modulation voltage reference signal and the state of charge reference signal calculated by the energy storage system parameter model, and the state of charge estimation signal output by the to-be-tested energy storage submodule, obtain a modulation voltage through state of charge control, generate a switching signal, and output the switching signal to the H-bridge circuit in the to-be-tested energy storage submodule.

[0026] Optionally, the state of charge control adopted by the submodule controller subtracts the state of charge estimation signal from the state of charge reference signal of the to-be-tested energy storage submodule, and obtains the modulation voltage of the to-be-tested energy storage submodule by superimposing the modulation voltage reference signal through a proportional element,

[0027] The proportional coefficient is adjusted so that the state of charge of the battery cluster of the to-be-tested energy storage submodule is the same as the state of charge reference signal, and thus the internal potential and output voltage of the battery cluster of the to-be-tested energy storage submodule are the same as the internal potential and output voltage of the battery cluster in the actual system.

[0028] Optionally, the energy storage system parameter model is further configured to obtain an operation condition of a target system in which the to-be-tested energy storage submodule is located, and output, to the current controller, a bridge arm current of a phase in which the to-be-tested energy storage submodule is located in the target system as the bridge arm current reference signal;

[0029] Optionally, the energy storage system parameter model is further configured to obtain an operation condition of a target system in which the to-be-tested energy storage submodule is located, and output, to the current controller, a bridge arm current of a phase in which the to-be-tested energy storage submodule is located in the target system as the bridge arm current reference signal;

[0030] According to one aspect of the present application, a test method for a high-voltage direct-coupled energy storage sub-module test system is provided, comprising:

[0031] S1, selecting any one of the actual high-voltage direct-coupled energy storage equipment as the energy storage sub-module to be tested, and the energy storage system parameter model generates the reference bridge arm current i arm_ref , the reference modulation voltage u m_ref of the bridge arm where the energy storage sub-module to be tested is located, and the reference state of charge soc ref of the energy storage sub-module to be tested,

[0032] outputting the reference bridge arm current i arm_ref to the current controller, outputting the reference modulation voltage u m_ref and the reference state of charge soc ref to the sub-module controller through the energy storage system parameter model;

[0033] S2, detecting the test current signal i arm output by the current generator and the port voltage signal u com of the energy storage sub-module to be tested, and outputting to the current controller;

[0034] S3, estimating the state of charge soc of the battery cluster by the battery management system of the energy storage sub-module to be tested, and outputting to the sub-module controller;

[0035] S4, in the current controller, the test current signal i arm and the reference bridge arm current i arm_ref are subtracted, the voltage modulation wave is obtained through proportional integral resonant control, the port voltage signal u com of the energy storage sub-module to be tested is superimposed, and the switching signal for driving the power semiconductor device in the current generator is generated through carrier phase shift modulation or carrier superposition modulation, so that the test current signal i arm is the same as the reference bridge arm current i arm_ref ;

[0036] S5, in the sub-module controller, the state of charge soc of the battery cluster of the energy storage sub-module to be tested and the reference state of charge soc ref are subtracted, the voltage modulation wave is obtained through state of charge control, the reference modulation voltage u m_ref is superimposed, and the switching signal for driving the power semiconductor device in the energy storage sub-module to be tested is generated through the modulation strategy conforming to the target system, so that the voltage of the energy storage sub-module to be tested, the state of charge of the battery cluster are the same as the voltage of the actual energy storage sub-module, and the state of charge of the battery cluster.

[0037] Optionally, each calculation step in S4 and S5 is realized by a chip including a digital signal processor or a field programmable logic gate array, an operation circuit or software.

[0038] Compared with the prior art, the application has the following beneficial effects:

[0039] 1. The energy storage submodule test system of the high-voltage direct-hanging energy storage equipment provided by the application can generate the same submodule current, submodule state of charge and submodule voltage as the actual system operation state according to the current generator, current controller and submodule controller, so as to realize the simulation of the operation condition of any energy storage submodule of the high-voltage direct-hanging large-capacity energy storage system by the to-be-tested energy storage submodule, and the test can be performed without building a complete system, thereby greatly reducing the test cost and having high test precision and high efficiency.

[0040] 2. The current generator with a cascade structure provided by the application can output more levels, so that the test system reduces the demand for filters and switching frequencies under the condition that the size of the test current ripple is unchanged, or reduces the current ripple of the test current under the condition that the demand for filters and switching frequencies is unchanged.

[0041] 3. The current generator with a cascade structure provided by the application can reduce the DC power supply voltage by increasing the number of cascade full bridges, so that the withstand voltage requirement of the power semiconductor devices in the current generator is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0042] The drawings described herein are used to provide further understanding of the application, constitute a part of the application, and the illustrative embodiments of the application and the description thereof are used to explain the application, and do not constitute an improper limitation on the application. In the drawings:

[0043] Figure 1 The energy storage submodule test circuit and its control block diagram of a high-voltage direct-hanging energy storage equipment provided in a preferred embodiment of the application;

[0044] Figure 2 The energy storage submodule test circuit topology schematic diagram of a high-voltage direct-hanging energy storage equipment provided in a preferred embodiment of the application;

[0045] Figure 3 The current controller control block diagram of the energy storage submodule test system of a high-voltage direct-hanging energy storage equipment provided in a preferred embodiment of the application;

[0046] Figure 4 The submodule controller control block diagram of the energy storage submodule test system of a high-voltage direct-hanging energy storage equipment provided in a preferred embodiment of the application.

[0047] In the figure: 1 - current generator; 11 - constant voltage DC source of the current generator; 12 - cascaded full-bridge circuit of the current generator; 13 - filter of the current generator; 2 - to-be-tested energy storage sub-module; 21 - H-bridge circuit of the to-be-tested energy storage sub-module; 22 - buffer and isolation unit of the to-be-tested energy storage sub-module; 23 - battery cluster of the to-be-tested energy storage sub-module; 3 - current controller; 31 - proportional integral resonance control module of the current controller; 32 - modulation module of the current controller; 4 - sub-module controller; 41 - state of charge control module of the sub-module controller; 42 - modulation module of the sub-module controller; 5 - energy storage system parameter model. DETAILED DESCRIPTION

[0048] In order to make the purposes, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0049] As described above, the existing high-voltage direct-hanging large-capacity energy storage test system has problems such as high system voltage level, large number of required sub-modules, inflexible test, high cost, inability to apply voltage and current stress conforming to actual working conditions, and large test current ripple.

[0050] Based on this, the present application proposes an energy storage sub-module test system and test method of high-voltage direct-hanging energy storage equipment to realize simulation of any energy storage sub-module working condition of the to-be-tested sub-module on the high-voltage direct-hanging large-capacity energy storage system, reduce the test system current ripple, and realize efficient and accurate test of the energy storage sub-module operating at a lower switching frequency.

[0051] When the current generator adopts a cascaded structure, the output voltage harmonic is greatly reduced due to the increase of the number of output levels of the current generator, thereby reducing the test system current ripple, which not only improves the test accuracy, but also reduces the requirements for the switching frequency of the current generator, the filter and the DC power supply. At the same time, through the state of charge control of the battery cluster of the to-be-tested energy storage sub-module, the state of charge, internal potential and output voltage of the battery cluster of the to-be-tested energy storage sub-module can be kept consistent with the actual system, thereby realizing simulation of the working condition of the battery cluster of the to-be-tested energy storage sub-module.

[0052] In a preferred embodiment of the present application, as shown in Figure 1 and Figure 2 a kind of energy storage sub-module test system of high-voltage direct-hanging energy storage equipment is proposed, comprising:

[0053] A current generator 1 for generating a test current, the current generator comprising a cascaded full-bridge circuit 12 of the current generator (shown in the figure as a cascaded H-bridge), a constant-voltage DC source 11 of the current generator, and a filter 13 of the current generator. The current generator adopts carrier phase-shift modulation or carrier layer superposition modulation for the converter in the cascaded full-bridge structure, the number of cascaded full-bridges and the filter can be designed according to the current ripple requirement, and based on the carrier phase-shift or carrier layer superposition modulation, the harmonic content of the output voltage of the current generator 1 can be reduced.

[0054] A to-be-tested energy storage sub-module 2, which is an energy storage module actually applied to a high-voltage direct-connection large-capacity energy storage system and operates under carrier phase-shift or carrier layer superposition sinusoidal pulse width modulation, comprises an H-bridge circuit 21 of the to-be-tested energy storage sub-module, a buffer and isolation unit 22 of the to-be-tested energy storage sub-module, a battery cluster 23 of the to-be-tested energy storage sub-module, and a corresponding battery management system. The test system realizes testing by applying a current and a control signal conforming to an actual operating condition to the to-be-tested energy storage sub-module 2. Meanwhile, the H-bridge circuit operates under carrier phase-shift or carrier layer superposition sinusoidal pulse width modulation, and the battery management system can estimate the state of charge of the battery cluster and output the estimated value to the sub-module controller for state of charge control of the battery cluster.

[0055] The test system further comprises:

[0056] A current controller 3 for receiving a test current sampling signal output by the current generator 1 and a port voltage signal of the to-be-tested energy storage sub-module, and generating a control signal of the current generator 1, so as to adjust the output current of the current generator 1, so that the output current of the current generator 1 is the same as the actual operating current of the actual energy storage sub-module.

[0057] A sub-module controller 4 for receiving a state of charge estimation signal output by the to-be-tested energy storage sub-module 2, generating a control signal of the to-be-tested energy storage sub-module 2 through state of charge control, and adjusting the voltage and the state of charge of the battery cluster of the to-be-tested energy storage sub-module 2 to be the same as the actual operating voltage and the state of charge of the battery cluster of the actual energy storage sub-module.

[0058] In an embodiment of the present application, the test system further comprises an energy storage system parameter model 5 for describing the behavior characteristics of the simulated high-voltage direct-connection large-capacity energy storage system, and outputting a corresponding bridge arm current reference signal to the current controller according to system operating parameters and the specifications of the energy storage sub-module; and for outputting a state of charge reference signal and a modulation voltage reference signal to the sub-module controller.

[0059] In a preferred embodiment of the present application, the energy storage system parameter model 5 obtains the working conditions such as voltage and current of the target system by theoretical calculation, simulation analysis or experimental recording on the target system in which the energy storage sub-module to be tested is located, and outputs the bridge arm current of the phase in which the energy storage sub-module 2 to be tested is located in the target system as a bridge arm current reference signal to the current controller 3; and outputs the bridge arm voltage of the phase in which the energy storage sub-module 2 to be tested is located in the target system as a modulation voltage reference signal, and outputs the average value of the state of charge of the battery cluster in which the energy storage sub-module 2 to be tested is located as a state of charge reference signal to the sub-module controller 4.

[0060] Specifically, the energy storage sub-module test system of the high-voltage direct-hanging energy storage equipment provided in a preferred embodiment of the present application has a circuit structure and a control block diagram as shown in the figure. Figure 1 The main circuit of the test circuit includes a current generator 1 in a cascade structure and an energy storage sub-module 2 to be tested. The current generator 1 further includes n cascade full-bridge circuits, n constant-voltage DC sources and a filter 13 of the current generator. In the control system of the test circuit, an energy storage system parameter model 5 generates a current reference value i arm_ref , a modulation voltage reference value u m_ref and a state of charge reference value soc ref , and inputs the reference values to a current controller 3 and a sub-module controller 4 respectively; the current controller 3 receives the current reference value i arm_ref generated by the energy storage system parameter model 5, a test current sampling signal i arm sampled and a port voltage u com of the energy storage sub-module to be tested sampled, and outputs the switching signals required by the cascade full-bridge circuits in the current generator 1; the sub-module controller 4 receives the modulation voltage reference value u m_ref and the state of charge reference value soc ref generated by the energy storage system parameter model 5, and the state of charge soc of the battery cluster 23 of the energy storage sub-module to be tested estimated, and outputs the switching signals required by the full-bridge modules in the energy storage sub-module 2 to be tested.

[0061] The energy storage sub-module test system of the high-voltage direct-hanging energy storage equipment provided in the embodiment can make the energy storage sub-module to be tested simulate the actual working conditions of any energy storage sub-module in a high-voltage direct-hanging large-capacity energy storage system through the current generator and the corresponding current controller and sub-module controller, greatly reducing the test cost, and having high test precision and high efficiency.

[0062] As a preferred embodiment, when the current generator 1 contains n cascade full-bridges and the power supply voltage of a single full-bridge is Vs, the current generator 1 can output a range of -nV s to nV s2n+1 levels. The filter of the current generator is composed of an inductance or a combination of inductance and capacitance, and the more levels reduce the output voltage harmonics of the current generator 1, and further reduce the test current ripple output by the current generator 1.

[0063] In the preferred embodiment described above, the current generator 1 and the to-be-tested energy storage sub-module 2 adopt the circuit topology shown in the figure, which includes but is not limited to Figure 2

[0064] In the preferred embodiment described above, the filter 13 of the current generator is composed of one or more elements such as inductance, capacitance, and resistance, and can adopt circuit topologies including but not limited to pure inductance, resistance-inductance series, LCL filter, etc.

[0065] In the preferred embodiment described above, the relationship between the maximum test current ripple and the switching frequency of the current generator, the filter inductance, and the number of cascaded full-bridge can be expressed as:

[0066]

[0067] Wherein, i ripp l e_max is the maximum test current ripple, V s is the supply voltage of the current generator, f s is the switching frequency of the current generator, L t is the filter inductance of the current generator, and n gen is the number of cascaded full-bridge of the current generator. This relationship shows that the maximum test current ripple is inversely proportional to the product of the switching frequency of the current generator, the filter inductance, and the number of cascaded full-bridge. Therefore, under the condition that the maximum test current ripple remains unchanged, the filter inductance and the switching frequency of the current generator can be reduced by increasing the number of cascaded full-bridge of the current generator.

[0068] In a preferred embodiment of the present application, the maximum output voltage of the current generator is equal to the product of the number of cascaded full-bridge of the current generator and the supply voltage of the current generator, which needs to be at least greater than the sum of the filter inductance voltage of the current generator and the port voltage of the to-be-tested power electronic battery sub-module. The maximum port voltage of the to-be-tested power electronic battery sub-module can be expressed as the sum of the DC component and the maximum voltage ripple of the parallel capacitor voltage of the to-be-tested power electronic battery sub-module, and the supply voltage of the current generator and the number of cascaded full-bridge can be designed according to the above relationship.

[0069] Specifically, in the preferred embodiment described above, the relationship between the output voltage of the current generator, the filter inductance of the current generator, the DC component of the capacitor voltage of the to-be-tested energy storage sub-module, and the switching frequency of the to-be-tested energy storage sub-module can be expressed as: ​

[0070]

[0071] wherein, V gen is the output voltage of the current generator, n gen is the number of full-bridge cascaded in the current generator, V s is the power supply voltage of the current generator, ω is the angular frequency of the power frequency current, L t is the filter inductance value of the current generator, I t is the test current amplitude, V csm is the DC component of the capacitor voltage of the energy storage sub-module to be tested, f sm is the switching frequency of the energy storage sub-module to be tested, C sm is the capacitance value of the parallel capacitor of the energy storage sub-module to be tested. The relationship shows that, under the condition that the output voltage of the current generator is unchanged, the power supply voltage of the current generator can be reduced by increasing the number of full-bridge cascaded in the current generator.

[0072] In the above preferred embodiment, Figure 1 the current controller 3 can adopt the structure as shown in Figure 3 The current controller 3 receives the current reference value i arm_ref generated by the energy storage system parameter model 5, the sampled test current signal i arm , and the sampled port voltage u com of the energy storage sub-module to be tested, and then inputs the difference between i arm_ref and i arm to the proportional-integral-resonant control module 31 of the current controller, and then compensates u com at the output end of the proportional-integral-resonant controller 31 of the current controller, so as to offset the interference of the energy storage sub-module to be tested on the current control loop. Finally, the output modulated voltage u m_i generates the switching signal required by the current generator full-bridge cascaded in the modulation module 32 of the current controller.

[0073] Specifically,

[0074]

[0075] wherein, Δi is the difference between the test current reference value and the sampled value, i arm_ref is the test current reference value, i arm is the test current sampling value, u m_i is the modulated voltage, k p is the proportional control coefficient, k i is the integral control coefficient, ω1 is the fundamental frequency of the current, ω2 is the double frequency of the current, k r1 is the resonant control coefficient of ω1, k r2 is the resonant control coefficient of ω2, ucom The port voltage of the to-be-tested energy storage sub-module is compensated.

[0076] In the preferred embodiment, the modulation module 32 of the current controller adopts carrier phase-shifted modulation or carrier superimposed modulation. Specifically, when the number of cascaded full-bridge circuits 12 of the current generator is n, if carrier phase-shifted modulation is adopted, n triangular carriers with a range of -1 to 1 and a phase angle difference of 2π / n are needed; if carrier superimposed modulation is adopted, n triangular carriers with a range of -1 to 1, the same phase angle and a difference of 2 / n between adjacent amplitudes are needed. In the modulation module 32 of the current controller, the switching signals of the power semiconductor devices in the n full-bridge circuits are obtained by comparing the modulation wave with the above-mentioned triangular carriers.

[0077] In the preferred embodiment, Figure 1 The sub-module controller 4 can adopt the structure as shown in Figure 4 .

[0078] After receiving the modulation voltage reference signal u m_ref , the state-of-charge reference signal soc ref and the state-of-charge estimation signal soc of the to-be-tested energy storage sub-module battery cluster generated by the energy storage system parameter model 5, the sub-module controller inputs the difference between socref and soc into the state-of-charge control module 41 of the sub-module controller, outputs a compensation voltage through calculation, superimposes u m_ref , and obtains the modulation voltage u m_u . Finally, the switching signals required by the full-bridge module 21 of the to-be-tested energy storage sub-module are generated in the modulation module 42 of the sub-module controller.

[0079] The state-of-charge control adopted by the sub-module controller subtracts the state-of-charge reference signal and the estimation signal of the to-be-tested energy storage sub-module, superimposes the modulation voltage reference signal through a proportional link to obtain the modulation voltage of the to-be-tested energy storage sub-module, and adjusts the proportional coefficient to make the state-of-charge of the battery cluster of the to-be-tested energy storage sub-module the same as the state-of-charge reference signal, so as to make the internal potential and output voltage of the battery cluster of the to-be-tested energy storage sub-module the same as the internal potential and output voltage of the battery cluster in the actual system.

[0080] Specifically,

[0081]

[0082] wherein Δsoc is the difference between the state-of-charge reference value and the estimation value of the to-be-tested energy storage sub-module battery cluster, soc ref is the state-of-charge reference value of the sub-module battery cluster, soc is the state-of-charge estimation value of the sub-module battery cluster, u m_u is the modulation voltage, k soc is the proportional control coefficient, and Enom is the rated voltage of the to-be-tested energy storage sub-module battery cluster, ω is the target energy storage system output current angular frequency, is the target energy storage system output current phase angle, u m_ref is the modulation voltage reference signal.

[0083] In the preferred embodiment described above, the sub-module controller modulation module 42 adopts a modulation mode conforming to the target energy storage sub-module, including but not limited to unipolar sine pulse width modulation, bipolar sine pulse width modulation, and unipolar frequency-doubled sine pulse width modulation.

[0084] In the preferred embodiment described above, the estimation method of the battery cluster state of charge of the to-be-tested energy storage sub-module battery management system includes but is not limited to ampere-hour integration, internal resistance, Kalman filtering, and open-circuit voltage. Taking the ampere-hour integration method as an example, the current state of charge of the battery is estimated through the known initial state of charge of the battery and the sampled battery charging and discharging current,

[0085] Specifically,

[0086]

[0087] wherein soc(t) is the battery state of charge estimation value at time t, soc(t0) is the battery state of charge at the initial time t0, C N is the battery rated charge amount, and i(t) is the battery charging and discharging current at time t.

[0088] By adopting the cascade structure current generator, the test circuit can keep the maximum test current ripple unchanged, reduce the demand of the test circuit on the switching frequency of the current generator and the filter in the current generator, or keep the switching frequency of the current generator and the filter in the current generator unchanged, and reduce the maximum test current ripple. By increasing the number of cascaded full bridges in the current generator, the supply voltage can be reduced, so that the withstand voltage requirement of the power semiconductor devices in the current generator is reduced. At the same time, the sub-module state of charge control adopted in the sub-module controller can simulate the state of charge of the sub-module battery cluster in the actual system, so as to accurately control the sub-module voltage and realize the simulation of the operation condition of any energy storage sub-module of the target energy storage system.

[0089] In an embodiment of the present application, a test method of the energy storage sub-module test system of the high-voltage direct-hanging energy storage equipment is also provided, which includes:

[0090] S1, selecting any energy storage sub-module that needs to be simulated in the actual high-voltage direct-hanging energy storage equipment as the to-be-tested energy storage sub-module, and the energy storage system parameter model generates the reference bridge arm current i arm_ref and the reference modulation voltage u of the bridge arm where the to-be-tested energy storage sub-module is locatedm_ref and reference state of charge soc of the bridge arm where the energy storage sub-module under test is located ref ,

[0091] the reference bridge arm current i arm_ref is output to a current controller, and the reference modulation voltage u m_re f and reference state of charge soc ref are output to a sub-module controller;

[0092] S2, a test current signal i arm output by a current generator is detected, and the port voltage signal u com of the energy storage sub-module under test is detected, and output to the current controller;

[0093] S3, the state of charge soc of the battery cluster is estimated by a battery management system of the energy storage sub-module under test, and output to the sub-module controller;

[0094] S4, in the current controller, the test current signal i arm is subtracted from the reference bridge arm current i arm_ref , a voltage modulation wave is obtained by proportional-integral-resonant control, the port voltage signal u com of the energy storage sub-module under test is superimposed, and a switching signal for driving a power semiconductor device in a current generator is generated by carrier phase-shifted modulation or carrier laminated modulation, so that the test current signal i arm is the same as the reference bridge arm current i arm_ref ;

[0095] S5, in the sub-module controller, the state of charge soc of the battery cluster of the energy storage sub-module under test is subtracted from the reference state of charge soc ref , a voltage modulation wave is obtained by state of charge control, the reference modulation voltage u m_re f is superimposed, and a switching signal for driving a power semiconductor device in the energy storage sub-module under test is generated according to a modulation strategy conforming to a target system, so that the voltage of the energy storage sub-module under test and the state of charge of the battery cluster are the same as the voltage of an actual energy storage sub-module and the state of charge of the battery cluster.

[0096] Further, each calculation step in S4 and S5 is implemented by a chip including a digital signal processor or a field programmable logic gate array, an operation circuit, or software.

[0097] It should be noted that the above test method can control the energy storage submodule test system of the high-voltage direct-hanging energy storage equipment provided in the foregoing embodiments, and the related explanations about the test method of the energy storage submodule of the high-voltage direct-hanging energy storage equipment are also applicable to the test system of the energy storage submodule of the high-voltage direct-hanging energy storage equipment, which will not be described here again.

[0098] It should be noted that in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more. It should also be noted that the term "comprise" "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of another identical element in the process, method, article or equipment including the element.

[0099] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "one embodiment", "example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0100] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or changes within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. A test system for energy storage submodules of high-voltage direct-mounted energy storage equipment, characterized in that: include: A current generator, configured to generate a test current, the current generator comprising at least a cascade full-bridge circuit and a constant-voltage DC source; An energy storage submodule to be tested, the energy storage submodule to be tested comprising at least an H-bridge circuit and a battery cluster, the testing system implementing the test by applying a current and a control signal that conform to actual operating conditions to the energy storage submodule to be tested; The test system further comprises: a current controller, configured to receive the test current sampling signal output by the current generator and the voltage signal of the energy storage submodule port to be tested, and generate a control signal for the current generator so that the output current of the current generator is the same as the actual operating current of the actual energy storage submodule; a submodule controller, configured to receive a state-of-charge estimation signal output by the energy storage submodule to be tested, generate a control signal for the energy storage submodule to be tested, and adjust the voltage and battery cluster state-of-charge of the energy storage submodule to be tested to be the same as the actual operating voltage and battery cluster state-of-charge of the actual energy storage submodule; The state of charge control adopted by the submodule controller is to make a difference between the state of charge reference signal of the energy storage submodule to be tested and the estimated signal, and to obtain the modulation voltage of the energy storage submodule to be tested by superimposing the modulation voltage reference signal through a proportional link. By adjusting the proportional coefficient, the state of charge of the energy storage submodule battery cluster to be tested is made the same as the state of charge reference signal, thereby making the internal potential and output voltage of the energy storage submodule battery cluster to be tested the same as the internal potential and output voltage of the battery cluster in the actual system.

2. The test system according to claim 1, wherein: The cascade full-bridge circuit of the current generator includes at least n, The DC side of the cascaded full-bridge circuit has n output voltages V s It is connected to a DC voltage source, or to n DC terminals of a multi-winding transformer after rectification.

3. The test system according to claim 1, wherein: The cascade full-bridge circuit in the current generator adopts carrier phase shift modulation or carrier stacking modulation. When carrier phase shift modulation is used, n adjacent triangular carriers with a phase angle difference of 2π / n between -1 and 1 are used; When carrier stacking modulation is adopted, n triangular carriers are used, which have the same phase angle between -1 and 1 and the adjacent amplitude differences are 2 / n.

4. The test system according to claim 1, wherein: The maximum output voltage of the current generator is equal to the product of the number of cascaded full bridges of the current generator and the supply voltage of the current generator, and is not less than the sum of the voltage of the filter inductor of the current generator and the port voltage of the energy storage submodule to be tested. The maximum voltage value of the port of the energy storage submodule to be tested is represented by the sum of the DC component of the parallel capacitor voltage and the maximum voltage ripple value of the energy storage submodule to be tested.

5. The test system according to claim 1, wherein: The test system further comprises: An energy storage system parameter model, configured to output a corresponding bridge arm current reference signal to the current controller based on system operating parameters and the specifications of the energy storage submodule; It is also used to output a state of charge reference signal and a modulation voltage reference signal to the submodule controller.

6. The test system according to claim 5, characterized in that: The current controller is used to receive the bridge arm current reference signal calculated by the energy storage system parameter model, the sampled test current signal, and the port voltage signal of the energy storage submodule to be tested, obtain a modulation voltage through proportional-integral resonant control, generate a switching signal, and output it to the cascaded full-bridge circuit in the current generator.

7. The test system according to claim 5, characterized in that: The submodule controller is configured to receive a modulation voltage reference signal and a state of charge reference signal calculated by the energy storage system parameter model, as well as a state of charge estimation signal output by the energy storage submodule to be tested, obtain a modulation voltage through state of charge control, generate a switching signal, and output the signal to the H-bridge circuit in the energy storage submodule to be tested.

8. The test system according to claim 5, wherein: The energy storage system parameter model is further used to obtain the operating condition of the target system where the energy storage submodule to be tested is located, and to output the bridge arm current of the phase where the energy storage submodule to be tested is located in the target system as a bridge arm current reference signal to the current controller; The bridge arm voltage of the phase where the energy storage submodule to be tested is located in the target system is used as the modulation voltage reference signal, and the average state of charge of the battery cluster of the phase where the energy storage submodule to be tested is located is used as the state of charge reference signal, which is output to the submodule controller.

9. A method for testing an energy storage submodule test system using the high-voltage direct-mounted energy storage equipment according to any one of claims 1 to 8, characterized in that: include: S1. Select any energy storage submodule that needs to be simulated in the actual high-voltage direct-mounted energy storage equipment as the energy storage submodule to be tested. The energy storage system parameter model generates a reference bridge arm current i corresponding to the energy storage submodule to be tested. arm_ref , the reference modulation voltage u of the bridge arm where the energy storage submodule to be tested is located m_ref And the reference state of charge SOC of the bridge arm where the energy storage submodule to be tested is located ref , The reference bridge arm current i is converted into arm_ref Output to the current controller, the reference modulation voltage u m_ref and reference state of charge soc ref Output to submodule controller; S2, test current signal i output by the detection current generator arm and the voltage signal u of the energy storage submodule port to be tested com , and output to the current controller; S3, using the battery management system of the energy storage submodule to be tested to estimate the state of charge (SOC) of the battery cluster, and output it to the submodule controller; S4, in the current controller, the test current signal i arm and the reference bridge arm current i arm_ref The voltage modulation wave is obtained by proportional integral resonant control and the voltage signal u of the energy storage submodule to be tested is superimposed. com , and then generate a switching signal for the power semiconductor device in the driving current generator through carrier phase shift modulation or carrier stacking modulation, so that the test current signal i arm With the reference bridge arm current i arm_ref same; S5, in the submodule controller, the state of charge (SOC) of the energy storage submodule battery cluster to be tested and the reference state of charge (SOC) ref The voltage modulation wave is obtained by controlling the state of charge and superimposing the reference modulation voltage u m_ref , and then generate a switching signal to drive the power semiconductor device in the energy storage submodule to be tested through a modulation strategy that conforms to the target system, so that the voltage of the energy storage submodule to be tested and the state of charge of the battery cluster are the same as the actual energy storage submodule voltage and the state of charge of the battery cluster.

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