Energy storage simulation system and analysis method based on simulation model

Abstract

The invention provides an energy storage simulation system and an analysis method based on a simulation model, and the system comprises a simulation module which builds a simulation model comprising a photovoltaic system and an energy storage device, simulates a power grid adjustment strategy through the simulation model, and outputs a simulation report; the PI D controller is used for controlling the output power of the energy storage device and maintaining the power of the grid-connected point within a set range by compensating a power curve of the photovoltaic system; the oscilloscope is used for collecting voltage, current and power data at the two ends of the photovoltaic system, the energy storage device and the grid-connected point, after the simulation command is executed, a simulation waveform is displayed on an interface of the oscilloscope, the simulation waveform is analyzed, the reliability of the energy storage simulation system in different operation states is evaluated, and a system reliability report is generated; the direct current side protection circuit is used for protecting direct current components of the photovoltaic system and the energy storage device; and the alternating current side protection circuit is used for protecting the alternating current sides of the photovoltaic system and the energy storage device.

Description

Technical Field

[0001] The present invention relates to the technical field of model simulation, and in particular, to an energy storage simulation system and an analysis method based on a simulation model. Background Technique

[0002] With the rapid development of energy storage technology, the capacity of energy storage devices is getting larger and larger. The capacity of energy storage containers has reached up to 6.4 Mwh at most, and the capacity of outdoor energy storage cabinets is also gradually increasing. The larger the capacity, the higher the requirement for the reliability of the product. Whether the energy storage system can meet the requirements of the power grid after being connected to the grid is a test. In addition, with the rapid development of renewable energy technology and the urgent global demand for carbon emission reduction, photovoltaic and energy storage technologies have become important components in the energy field. The photovoltaic system can directly convert solar energy into electrical energy, while the energy storage system can store this electrical energy for emergencies or to balance the electrical energy generated by the photovoltaic system and the grid demand. The capacity and performance of energy storage devices are crucial for ensuring grid stability, improving power quality, and reducing energy waste.

[0003] Currently, energy storage technology is undergoing a transformation from single energy storage products to more complex and integrated energy storage systems. These systems usually include multiple components such as batteries, inverters, and control systems, which need to work together to meet various demands of the power grid. As the capacity of energy storage systems increases, the requirements for their reliability, efficiency, and response speed also increase accordingly. Especially in the application scenario of photovoltaic plus energy storage, how to optimize the system configuration to ensure the dynamic balance of power supply and demand has become an urgent problem to be solved.

[0004] Although the simulation of a single energy storage system can predict the basic performance of the system, it often lacks a comprehensive simulation of the integration of the photovoltaic system and cannot accurately reflect the actual operation of the energy storage system in the photovoltaic plus energy storage environment. In addition, existing simulation technologies often fail to provide detailed model building instructions, parameter setting bases, and specific analyses of simulation results, which limits the application of simulation technologies in the optimization of energy storage systems. Summary of the Invention

[0005] The main object of the present invention is to provide an energy storage simulation system and an analysis method based on a simulation model to solve the problem in the related art that the simulation scheme of a single energy storage system lacks the simulation of the integration of the photovoltaic system, is prone to cause imbalance between power supply and demand, and affects the power supply state.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided an energy storage simulation system, comprising: a simulation module for establishing a simulation model including a photovoltaic system and an energy storage device, simulating a grid regulation strategy by the simulation model, and outputting a simulation report, wherein the grid regulation strategy includes: when the power generated by the photovoltaic system is greater than the power demand on the grid side, controlling the energy storage device to charge to consume the redundant power of the photovoltaic system; when the power generated by the photovoltaic system is less than the power demand on the grid side, controlling the energy storage device to discharge to the grid side to meet the insufficient power demand on the grid side. The simulation report includes the power curve of the photovoltaic system, the power curve of the energy storage device, voltage and current parameters, and the energy storage device is connected to the grid connection point on the grid side; a PID controller for controlling the output power of the energy storage device, maintaining the power at the grid connection point within a set range by compensating the power curve of the photovoltaic system; an oscilloscope for collecting voltage, current and power data at both ends of the photovoltaic system, the energy storage device and the grid connection point, displaying a simulation waveform on the interface of the oscilloscope after executing a simulation command, analyzing the simulation waveform, evaluating the reliability of the energy storage simulation system under different operating states, and generating a system reliability report; a DC side protection circuit for protecting the DC components of the photovoltaic system and the energy storage device; and an AC side protection circuit for protecting the AC side of the photovoltaic system and the energy storage device.

[0007] Optionally, the simulation model further includes: a maximum power point tracking module MPPT for adopting a conductance increment strategy to dynamically adjust the operating voltage of each photovoltaic module in the photovoltaic system to ensure that the photovoltaic system operates at the maximum power point.

[0008] Optionally, it further includes: an AC coupling module for coupling a photovoltaic inverter and an energy storage converter to an AC bus, wherein a DC contactor is configured on the DC side of the energy storage converter, and an AC relay is configured on the AC side of the fuse. The internal architecture of the energy storage converter is a DC / AC two-level four-leg topology.

[0009] Optionally, both the energy storage converter and the photovoltaic system are connected to a busbar copper row.

[0010] Optionally, the AC coupling module includes: a high-pass filter circuit for removing DC components through capacitive coupling, and the high-pass filter circuit is used to connect the photovoltaic system and the energy storage device to meet the grid connection conditions.

[0011] Optionally, when constructing the energy storage device, it includes: establishing a model of the inverter according to the topology of the photovoltaic inverter, and connecting the inverter and the battery system to form the energy storage device.

[0012] Optionally, it further includes: a reverse current prevention circuit, including a plurality of relays and a plurality of circuit breakers, for monitoring the real-time power generated by the photovoltaic system, using a digital signal processor (DSP) to compare the real-time power generated by the photovoltaic system with the required power on the user side. When the comparison result indicates that the power generated by the photovoltaic system exceeds the required power on the user side, it determines that there is a risk of reverse current, and controls the relay / circuit breaker to cut off the circuit to prevent reverse current.

[0013] Optionally, the DC side protection circuit includes: a transient voltage suppressor (TVS) and a preset capacitor. Among them, the preset capacitor is an element for storing charge, and the transient voltage suppressor (TVS) is used to absorb overvoltage when the voltage in the DC side protection circuit of the photovoltaic system exceeds the set threshold of the TVS diode, so as to protect other elements in the circuit.

[0014] Optionally, the AC side protection circuit includes: a varistor, a gas discharge tube, and a Y capacitor. Among them, the varistor is used to protect electrical equipment to prevent continuous current from being generated when the gas discharge tube discharges, and the Y capacitor is a three-terminal capacitor.

[0015] According to another aspect of the present invention, an analysis method based on a simulation model is provided, including: setting system parameters of a photovoltaic system and an energy storage device in the simulation model. Among them, the simulation model includes: a photovoltaic system sub-model, an energy storage device sub-model, and a power grid simulation sub-model. The energy storage device is connected to the grid connection point on the grid side, and the system parameters include a power curve, battery capacity, voltage, and current; connecting the photovoltaic system sub-model and the energy storage device sub-model through a universal bridge module and accessing the power grid simulation sub-model; applying a PID controller to control the output power of the energy storage device, and by compensating the power curve of the photovoltaic system, maintaining the power at the grid connection point within a set range; executing a simulation start command, simulating a grid regulation strategy, and collecting simulation data. Among them, the grid regulation strategy includes: when the power generated by the photovoltaic system is greater than the required power on the grid side, controlling the energy storage device to charge to consume the redundant power of the photovoltaic system; when the power generated by the photovoltaic system is less than the required power on the grid side, controlling the energy storage device to discharge to the grid side to meet the insufficient power demand on the grid side. Among them, the simulation data includes the power curve of the photovoltaic system, the power curve of the energy storage device, voltage, and current parameters; controlling an oscilloscope to collect waveforms at both ends of the photovoltaic system, the energy storage device, and the grid connection point to obtain simulation waveforms; based on the simulation waveforms and the simulation data, evaluating the grid connection performance and resource utilization rate of the energy storage simulation system, and outputting a simulation report.

[0016] Applying the technical solution of the present invention, the energy storage simulation system integrates the simulation models of the photovoltaic system and the energy storage device at the same time to realize photovoltaic energy storage simulation. And through the grid regulation strategy, the regulation of power supply and demand can be realized, the power curve of the photovoltaic can be compensated, and the photovoltaic curve at the grid connection point can be maintained within a constant power range. In addition, the voltage and current of the energy storage system and the voltage on the grid side can be collected through the PID controller, and the power difference on the grid side can be obtained through calculation. Through the real-time scheduling of the PID loop, the power can be supplemented into the grid to achieve balanced power supply, thus solving the problem in the related art that the simulation scheme of a single energy storage system lacks the simulation of the integration of the photovoltaic system, is prone to power supply and demand imbalance, and affects the power supply state. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 is a schematic diagram of an optional energy storage simulation system according to the present invention; and

[0019] Figure 2 is a schematic diagram of an optional energy storage simulation model according to an embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of an optional bidirectional energy storage inverter circuit according to an embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of an optional design circuit of a photovoltaic and energy storage system according to an embodiment of the present invention;

[0022] Figure 5 is a flowchart of an optional analysis method based on a simulation model according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment is actually only illustrative and in no way restrictive of the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangements of the components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationship. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0026] In this embodiment, the photovoltaic system and the energy storage device can be jointly simulated and optimized, and the simulation optimization system can be carried out in advance, which can save the system design cost and accurately calculate how much capacity of energy storage is required.

[0027] Figure 1 It is a schematic diagram of an optional energy storage simulation system according to the present invention, as Figure 1 shown, the energy storage simulation system includes: a simulation module 101, a PID controller 102, an oscilloscope 103, a DC side protection circuit 104, and an AC side protection circuit 105.

[0028] Among them, the simulation module 101 is used to establish a simulation model including a photovoltaic system and an energy storage device, simulate the grid regulation strategy by the simulation model, and output a simulation report. Among them, the grid regulation strategy includes: when the power generated by the photovoltaic system is greater than the power demand on the grid side, controlling the energy storage device to charge to consume the redundant power of the photovoltaic system; when the power generated by the photovoltaic system is less than the power demand on the grid side, controlling the energy storage device to discharge to the grid side to meet the insufficient power demand on the grid side. The simulation report includes the power curve of the photovoltaic system, the power curve of the energy storage device, voltage and current parameters, and the energy storage device is connected to the grid connection point on the grid side.

[0029] The simulation module in this embodiment can establish a simulation model, which correspondingly includes a model of a photovoltaic system connected to an energy storage device. The RMS (Monotonic Rate Scheduling Algorithm, which schedules based on task priorities) is used in the simulation module to perform power scheduling for the entire system.

[0030] Specifically, a sub-model corresponding to the energy storage device is constructed and set according to the cell model and system voltage. For example, the cell used in the outdoor cabinet is 314 Ah and the rated voltage is 768 V. A model of the inverter is established according to the topology of the inverter, and the inverter and the battery system are connected to form an energy storage system.

[0031] When constructing the sub-model corresponding to the photovoltaic system, the parameters of the photovoltaic sub-model are set by selecting the switching voltage and the number of series-connected strings of the photovoltaic system.

[0032] It should be noted that in this embodiment, the energy storage device is connected to the grid at the connection point. The open-circuit voltage, short-circuit current, component efficiency, temperature coefficient, series connection method, etc. of the photovoltaic are set for the photovoltaic module, and data such as voltage, capacity, and current are set for the energy storage battery.

[0033] When performing simulation, the simulation idea includes: when the power generated by the photovoltaic is greater than the demand on the grid side, at this time the energy storage device charges to help consume the redundant power of the photovoltaic; when the power generated by the photovoltaic is less than the demand on the grid side, the energy storage system discharges to meet the demand on the grid side.

[0034] Optionally, in this embodiment, the energy storage system and the photovoltaic system in the simulation software can be connected in the simulation model, so that the energy storage system and the photovoltaic system can work together. There are many VPN (Virtual Private Network, a technology that establishes an encrypted channel through a public network (such as the Internet) to enable users to securely access private networks or Internet resources) and IPN modules (Intelligent Personal Network, an intelligent personal network system that intelligently manages network connections according to the user's behavior patterns and habits to improve user experience and network performance) in the simulation diagram responsible for collecting voltage and current information and working in combination with an oscilloscope. Clicking on the oscilloscope module in the diagram can monitor the voltage and current of the system.

[0035] The PID controller 102 is used to control the output power of the energy storage device, and by compensating the power curve of the photovoltaic system, the power at the connection point is maintained within the set range.

[0036] The PID controller is a feedback control algorithm used in industrial control systems. The proportional term (P) generates a control quantity proportional to the current error based on the magnitude of the current error. The integral term (I) accumulates historical errors to eliminate steady-state errors. The derivative term (D) predicts future errors based on the error change rate.

[0037] By binding the energy storage device to the PID loop control, the power curve of the photovoltaic can be compensated, and the photovoltaic curve at the grid connection point can be maintained within a constant power range. The PID loop control collects the voltage and current of the energy storage system and the voltage on the grid side, calculates the power difference on the grid side, and performs real-time scheduling through the PID loop control to supplement the power into the grid.

[0038] The oscilloscope 103 is used to collect voltage, current, and power data at both ends of the photovoltaic system, energy storage device, and grid connection point. After executing the simulation command, the simulation waveform is displayed on the interface of the oscilloscope, the simulation waveform is analyzed, the reliability of the energy storage simulation system in different operating states is evaluated, and a system reliability report is generated.

[0039] For example, an oscilloscope is added to the output end of the photovoltaic system, an oscilloscope is added to the output end of the energy storage system, and an oscilloscope is added to both ends of the grid connection point. The oscilloscope collects voltage, current, and power data at each output end. By executing the simulation start command, waveforms will be displayed on the oscilloscope, and the simulation will automatically stop according to the set simulation time. The reliability analysis of the system can be carried out by analyzing the simulation waveforms.

[0040] Voltage and current data are collected through the oscilloscope. For example, if the voltage of the energy storage system is 768V, whether the voltage waveform displayed on the oscilloscope is 768V or whether the amplitude differs greatly. When the system is running, the models will affect each other, and the harmonics may increase. Start the entire simulation system and click on the THL harmonic analysis (Total Harmonic Distortion Level, which is an index used to measure the total amount of harmonic components contained in a signal in harmonic analysis. Usually, the THL value is expressed in percentage or decibel to evaluate the purity and distortion degree of the signal. The lower the THL value, the smaller the distortion degree of the signal) in the simulation software to automatically generate data.

[0041] The DC side protection circuit 104 is used to protect the DC components of the photovoltaic system and the energy storage device.

[0042] The AC side protection circuit 105 is used to protect the AC side of the photovoltaic system and the energy storage device.

[0043] The above energy storage simulation system can establish a simulation model including a photovoltaic system and an energy storage device through the simulation module 101. The simulation model simulates the grid regulation strategy, outputs a simulation report, controls the output power of the energy storage device through the PID controller 102, compensates for the power curve of the photovoltaic system, and maintains the power at the grid connection point within a set range. The oscilloscope 103 collects the voltage, current, and power data of the photovoltaic system, the energy storage device, and both ends of the grid connection point. After executing the simulation command, the simulation waveform is displayed on the interface of the oscilloscope, the simulation waveform is analyzed, the reliability of the energy storage simulation system in different operating states is evaluated, and a system reliability report is generated. At the same time, the DC components of the photovoltaic system and the energy storage device are protected by the DC side protection circuit 104, and the AC side of the photovoltaic system and the energy storage device are protected by the AC side protection circuit 105. In this embodiment, the energy storage simulation system integrates the simulation models of the photovoltaic system and the energy storage device at the same time, realizes the photovoltaic energy storage simulation, and realizes the regulation of power supply and demand through the grid regulation strategy. It can compensate for the power curve of the photovoltaic system, keep the photovoltaic curve at the grid connection point within a constant power range. In addition, it can also collect the voltage and current of the energy storage system and the voltage of the grid side through the PID controller, calculate the power difference on the grid side, and supplement the power to the grid in real time through the PID loop to achieve balanced power supply, thus solving the problem that the simulation scheme of a single energy storage system in the related technology lacks the simulation of the integration of the photovoltaic system, is prone to power supply and demand imbalance, and affects the power supply state.

[0044] Optionally, the simulation model further includes: a maximum power point tracking module MPPT, which is used to adopt a conductance increment strategy to dynamically adjust the operating voltage of each photovoltaic component in the photovoltaic system to ensure that the photovoltaic system operates at the maximum power point.

[0045] The working principle of the MPPT model is that the photovoltaic module changes with the operating voltage. Among them, the I-V curve is that the current decreases as the voltage increases, and the P-V curve is that the power first increases and then decreases as the voltage increases. There is a maximum power point (MPP). The core task of MPPT is to dynamically adjust the operating voltage of the photovoltaic module so that it operates near the MPP. The algorithm of MPPT adopts the conductance increment method, and the principle is to judge the working point position by comparing the conductance increment instantaneous conductance.

[0046] In this embodiment, by establishing an MPPT module associated with the photovoltaic system, the power of the photovoltaic is processed so that the photovoltaic always operates at the maximum power.

[0047] Figure 2 is a schematic diagram of an optional energy storage simulation model according to an embodiment of the present invention, as Figure 2As shown, the energy storage simulation model includes: a photovoltaic system (including the output current of the photovoltaic panel, the output current of the photovoltaic panel, MPPT (the conductance gain method is adopted for the algorithm), duty cycle calculation, PWM regulation, photovoltaic panel temperature setting, signal transmission device), an electrical energy graphical interface, a triode (Mosfet), a diode, a universal bridge, and the DC bus voltage output by the photovoltaic. The energy storage system (including the current strategy part, the voltage measurement part, the voltage and current measurement part of the photovoltaic and energy storage, and the voltage and current data after RMS regulation).

[0048] Optionally, the energy storage simulation system further includes: an AC coupling module for coupling the photovoltaic inverter and the energy storage converter to the AC bus. Among them, a DC contactor is configured on the DC side of the energy storage converter, and an AC relay is configured on the AC side of the fuse. The internal architecture of the energy storage converter is a DC / AC two-level four-arm topology.

[0049] It should be noted that for the photovoltaic converter and the energy storage converter in the energy storage and photovoltaic grid-connected simulation model, the simulation is actually carried out according to the topological structure of the specific product. For example, the parameters of the main component MOSFET (field effect transistor) in the converter are set. The on-resistance (Rds(on)) affects the conduction loss and efficiency, and the size of the internal diode inductance. The parameters of the series RLC load are set, including the rated voltage (nominal voltage vn) and the active power. Additionally, it should be noted that Figure 2 in [the figure], the PV Array is that the solar photovoltaic panel is converted into alternating current through the photovoltaic converter, and the Battery is that the lithium battery energy storage is converted into alternating current through the energy storage converter. The alternating current of the photovoltaic system and the alternating current of the energy storage device are merged into the grid together through the universal bridge.

[0050] Figure 2 The output current (or voltage) of the photovoltaic module (the system module composed of each photovoltaic panel) in [the figure] adjusts the working voltage of each photovoltaic module in the photovoltaic system through the MPPT module to ensure that the photovoltaic system operates at the maximum power point. Then the duty cycle is calculated and modulated through the PWM modulation module, and then DC / AC (direct current to alternating current) conversion is performed through the photovoltaic converter to adjust the waveform of the output current. At the same time, the Battery of the energy storage system is converted into alternating current through the energy storage converter, and then the alternating current of the photovoltaic system and the alternating current of the energy storage device are merged into the grid together through the universal bridge (such as Figure 2 the grid voltage shown, which is located at 311V). During the grid connection process, the alternating current converted by the energy storage converter will be detected through the signal transmission device, and the DC bus voltage value of the energy storage current will be output.

[0051] It should be noted that the bi-directional energy storage inverter (a key device of the energy storage device) in this embodiment does not contain a transformer, has a three-phase four-wire output, with an output side of 380 / 400V, and can be directly connected to the low-voltage power grid, and can be well matched with photovoltaic power. The matching method is the AC coupling method. AC coupling means connecting both the photovoltaic inverter (a key device of the photovoltaic system) and the energy storage converter (a key device of the energy storage device) to the AC bus. It is simple to operate and each operates independently. In addition, the energy storage system can be off-grid and can withdraw from the power grid as a backup power source in case of an emergency. It should be noted that the communication method between the modules in this embodiment can be RS485 or network cable.

[0052] In addition, it should be noted that adding a DC contactor on the DC side of the energy storage converter and adding an AC relay on the AC side of the fuse can well protect the system. A pre-charge resistor is added to the DC side of the converter. When multiple PCSs are connected in parallel, the circulating current can be reduced.

[0053] In addition, it should be noted that the internal architecture of the energy storage converter in this embodiment is a DC / AC two-level four-arm topology, which can be used in outdoor cabinets within 1000V.

[0054] Furthermore, the energy storage system in this embodiment has its own BMS (Battery Management System, a system for managing the charging and discharging process of the batteries in the energy storage system, monitoring the battery status, and protecting the battery safety) and EMS (Energy Management System, a system for monitoring, controlling, and optimizing the overall operation of the energy storage system. According to factors such as grid demand and energy price, it intelligently manages the charging and discharging process of the energy storage system to achieve the optimal operation of the energy storage system). The BMS is responsible for collecting battery information and uploading it to the EMS, and the EMS communicates with the grid side for unified scheduling by the grid. The energy storage converter can be grid-connected or off-grid.

[0055] Figure 3 is an optional circuit diagram of a bi-directional energy storage inverter according to an embodiment of the present invention, as Figure 3 shown, including: BAT+, DC Filter, fuse, LCL Filter, AC Relays, AC Filter.

[0056] Among them, the DC Filter is a DC filter, whose function is to filter out harmonics in the DC circuit, reduce the impact of harmonics on the power system, and stabilize the DC signal. The LCL Filter is an LCL filter, and its main function is to reduce high-frequency harmonics and electromagnetic interference (EMI) in the inverter output. The AC Relays are AC relays, and their functions include: 1. Controlling the charging and discharging of the PCS; 2. Protecting function. When the system detects overcurrent or overvoltage, the AC relay can quickly cut off the circuit; 3. Electrical isolation. The AC Filter is an AC filter, and its function is to filter out harmonics of specific frequencies to make the current and voltage close to the ideal sine wave. Optionally, both the energy storage converter and the photovoltaic system are connected to the 380V busbar copper row.

[0057] Optionally, the AC coupling module includes: a high-pass filter circuit (for example, an RC high-pass filter circuit, a circuit for filtering out low-frequency signals, such as removing DC bias signals or low-frequency noise), which is coupled through a DC-blocking capacitor to remove the DC component. The high-pass filter circuit is used to connect the photovoltaic system and the energy storage device for circuit connection to meet the grid connection conditions.

[0058] It should be noted that in the photovoltaic system: the output of the photovoltaic panel is DC electricity, but the grid-connected or hybrid system needs to be converted into AC electricity. If it is directly coupled, the DC component may cause saturation, efficiency reduction or damage of equipment (such as transformers). The characteristics of the energy storage device are: the battery charges and discharges in DC, but the energy storage inverter is connected to the AC bus. If the DC component flows into the AC side, it may interfere with the control circuit or cause harmonic problems.

[0059] To ensure the purity of the AC bus, in the AC coupling architecture, both the photovoltaic inverter and the energy storage inverter need to be connected to the same AC bus. In this embodiment, the DC-blocking capacitor is used to ensure that the bus only transmits AC energy, avoiding DC interference and system control chaos (such as power scheduling, voltage and frequency synchronization). To better realize the circuit connection between the photovoltaic system and the energy storage device, the DC component in the DC-blocking capacitor is cleared to meet the grid connection conditions.

[0060] Optionally, when constructing the energy storage device, it includes: establishing a model of the inverter according to the topological structure of the photovoltaic inverter, and connecting the inverter and the battery system to form the energy storage device.

[0061] Optionally, the energy storage simulation system can also include: a reverse current prevention circuit, which includes multiple relays and multiple circuit breakers, and is used to monitor the real-time power generated by the photovoltaic system. The digital signal processor DSP is used to compare the real-time power generated by the photovoltaic system with the power demand of the user side. When the comparison result indicates that the power generated by the photovoltaic system exceeds the power demand of the user side, it is determined that there is a risk of reverse current, and the relay / circuit breaker is controlled to cut off the circuit to prevent reverse current.

[0062] Figure 4It is an optional circuit design diagram of a photovoltaic and energy storage system according to an embodiment of the present invention. As Figure 4 shown, it includes: a contactor K1, a high-pass filter circuit, an AC-side protection circuit, an anti-backflow circuit, an MPPT module, an inverter (connected to a circuit breaker), a circuit breaker (including QF1 / QF2 / QF3 / QF4), a DC-side protection circuit, and an energy storage system (connected to the inverter) connected by an AC bus.

[0063] As Figure 4 shown, the anti-backflow circuits K1, K2, K3, and K4 are relays, and QF1 and QF2 are circuit breakers. The anti-backflow circuit is controlled by a digital signal processor (DSP). If it is detected that the power flows from the user side to the grid, the control logic is activated, and the relay / circuit breaker directly cuts off the circuit to prevent backflow.

[0064] In addition, it should be noted that the core components of the anti-backflow circuit are current and voltage transformers. Among them, the current transformer is used to detect the current direction and magnitude in the circuit, convert the high current into a low current signal for the ammeter to process, and the voltage transformer is used to measure the circuit voltage, combine with the current signal to calculate the power direction, and analyze the current and voltage signals in real time through the control unit to judge the power flow direction (forward or reverse). When backflow (reverse power) is detected, the control logic is triggered to control the relay to directly disconnect the circuit connection to prevent backflow.

[0065] As Figure 4 shown, QF1 and QF2 are circuit breakers for power cables, K1 and K2 are relays controlled by voltage signals, and K3 and K4 are current signal relays. When the control unit collects current and voltage signals through current and voltage transformers, when there is backflow, the relays receive signals to control the circuit breakers QF1 and QF2 to disconnect.

[0066] Optionally, the DC-side protection circuit includes: a transient voltage suppressor TVS and a preset capacitor. Among them, the preset capacitor is an element for storing charge, and the transient voltage suppressor TVS is used to absorb overvoltage when the voltage in the DC-side protection circuit of the photovoltaic system exceeds the set threshold of the TVS diode to protect other elements in the circuit.

[0067] For example, the DC-side protection circuit of the photovoltaic system adopts a combination of a transient voltage suppressor and a DC-LINK capacitor. The DC-LINK capacitor is an element for storing charge, and its functions are to smooth the current, filter noise, and improve the power quality. The function of the transient voltage suppressor TVS is that when the voltage in the circuit exceeds the set threshold of the TVS diode, it will quickly change from a high-resistance state to a low-resistance state, quickly absorb the overvoltage and convert it into heat energy, thereby protecting other elements in the circuit.

[0068] It should be noted that the current photovoltaic inverter is an inverter with MPPT. The function of MPPT is as follows: due to the influence of external factors such as light intensity and environment on the solar cell, its output power is variable. The more electricity is generated under stronger light intensity. The photovoltaic inverter with MPPT maximum power tracking is to make full use of the solar cell and operate it at the maximum power point. That is to say, under the condition of unchanged solar radiation, the output power after having MPPT will be higher than that before having MPPT. The solar photovoltaic array first passes through the DC side protection circuit.

[0069] Optionally, the AC side protection circuit includes: a varistor, a gas discharge tube and a Y capacitor. Among them, the varistor is used to protect electrical equipment and prevent the generation of continuous current when the gas discharge tube discharges. The Y capacitor is a three-terminal capacitor.

[0070] In this embodiment, the AC side protection circuit is protected in the form of a varistor combined with a gas discharge tube in parallel with a Y capacitor. The varistor has many advantages such as fast response speed, good non-linear characteristics, and large current-carrying capacity, and can protect electrical equipment in time, effectively eliminating the problem of continuous current when the gas discharge tube discharges. The Y capacitor is a three-terminal capacitor, usually composed of two capacitors connected in opposite directions with a grounding terminal in the middle. It can improve impedance matching and reduce noise in a parallel circuit.

[0071] Figure 5 It is a flowchart of an optional analysis method based on a simulation model according to an embodiment of the present invention. As Figure 5 shown, the analysis method based on the simulation model includes:

[0072] Step S501, set the system parameters of the photovoltaic system and the energy storage device in the simulation model. Among them, the simulation model includes: a photovoltaic system sub-model, an energy storage device sub-model and a power grid simulation sub-model. The energy storage device is connected to the grid connection point on the grid side. The system parameters include a power curve, battery capacity, voltage, and current.

[0073] Step S502, connect the photovoltaic system sub-model and the energy storage device sub-model through a universal bridge module and connect them to the power grid simulation sub-model.

[0074] Step S503: Apply a PID controller to control the output power of the energy storage device. By compensating the power curve of the photovoltaic system, maintain the power at the grid connection point within the set range; execute the simulation start command, simulate the grid regulation strategy, and collect simulation data. The grid regulation strategy includes: when the power generated by the photovoltaic system is greater than the power demand on the grid side, control the energy storage device to charge to consume the redundant power of the photovoltaic system; when the power generated by the photovoltaic system is less than the power demand on the grid side, control the energy storage device to discharge to the grid side to meet the insufficient power demand on the grid side. The simulation data includes the power curve of the photovoltaic system, the power curve of the energy storage device, voltage and current parameters.

[0075] Step S504: Control the oscilloscope to collect the waveforms at both ends of the photovoltaic system, the energy storage device, and the grid connection point to obtain the simulation waveforms.

[0076] Step S505: Based on the simulation waveforms and simulation data, evaluate the grid connection performance and resource utilization rate of the energy storage simulation system, and output a simulation report.

[0077] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: The energy storage simulation system integrates the simulation models of the photovoltaic system and the energy storage device at the same time, realizes the photovoltaic energy storage simulation, and realizes the regulation of power supply and demand through the grid regulation strategy, which can compensate the power curve of the photovoltaic system and keep the photovoltaic curve at the grid connection point within a constant power range. In addition, the voltage and current of the energy storage system and the voltage on the grid side can be controlled by a PID controller, and the power difference on the grid side can be calculated through calculation. The power is supplemented to the grid in real time through the PID loop control to achieve balanced power supply, thus solving the problem in the related art that the simulation scheme of a single energy storage system lacks the simulation of the integration of the photovoltaic system, is prone to power supply and demand imbalance, and affects the power supply state.

[0078] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary explanation, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as a limitation on the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0079] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0080] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A energy storage simulation system, characterized in that, Including: A simulation module, which is used to establish a simulation model including a photovoltaic system and an energy storage device, simulate a grid regulation strategy by the simulation model, and output a simulation report. Wherein, the grid regulation strategy includes: when the power generated by the photovoltaic system is greater than the power demand on the grid side, controlling the energy storage device to charge to consume the redundant power of the photovoltaic system; when the power generated by the photovoltaic system is less than the power demand on the grid side, controlling the energy storage device to discharge to the grid side to meet the insufficient power demand on the grid side. The simulation report includes the power curve of the photovoltaic system, the power curve of the energy storage device, voltage and current parameters, and the energy storage device is connected to the grid connection point on the grid side; A PID controller, which is used to control the output power of the energy storage device and maintain the power at the grid connection point within a set range by compensating the power curve of the photovoltaic system; An oscilloscope, which is used to collect voltage, current and power data at both ends of the photovoltaic system, the energy storage device and the grid connection point, display a simulation waveform on the interface of the oscilloscope after executing a simulation command, analyze the simulation waveform, evaluate the reliability of the energy storage simulation system under different operating states, and generate a system reliability report; A DC-side protection circuit, which is used to protect the DC components of the photovoltaic system and the energy storage device; An AC-side protection circuit, which is used to protect the AC side of the photovoltaic system and the energy storage device.

2. The energy storage simulation system according to claim 1, wherein The simulation model further includes: A maximum power point tracking module MPPT, which is used to adopt a conductance gain strategy to dynamically adjust the operating voltage of each photovoltaic component in the photovoltaic system to ensure that the photovoltaic system operates at the maximum power point.

3. The energy storage simulation system according to claim 1, wherein It further includes: An AC coupling module, which is used to couple a photovoltaic inverter and an energy storage converter to an AC bus. Wherein, a DC contactor is configured on the DC side of the energy storage converter, and an AC relay is configured on the AC side of the fuse. The internal architecture of the energy storage converter is a DC / AC two-level four-arm topology.

4. The energy storage simulation system according to claim 3, wherein Both the energy storage converter and the photovoltaic system are connected to the busbar copper row.

5. The energy storage simulation system according to claim 3, wherein The AC coupling module includes: A high-pass filter circuit, which removes DC components through capacitive coupling. The high-pass filter circuit is used to connect the photovoltaic system and the energy storage device to meet the grid connection conditions.

6. The energy storage simulation system according to claim 1, wherein When constructing the energy storage device, it includes: Establishing a model of the inverter according to the topology of the photovoltaic inverter, and connecting the inverter and the battery system to form the energy storage device.

7. The energy storage simulation system according to claim 1, wherein It further includes: An anti-counterflow circuit, which includes a plurality of relays and a plurality of circuit breakers, is used to monitor the real-time power generated by the photovoltaic system, compare the real-time power generated by the photovoltaic system with the power demand on the user side by using a digital signal processor DSP. When the comparison result indicates that the power generated by the photovoltaic system exceeds the power demand on the user side, it is determined that there is a risk of counterflow of current, and the relay / circuit breaker is controlled to cut off the circuit to prevent counterflow.

8. The energy storage simulation system according to claim 1, wherein The DC-side protection circuit includes: Transient voltage suppressor TVS and a preset capacitor, wherein the preset capacitor is a component for storing charges, and the transient voltage suppressor TVS is used to absorb overvoltage when the voltage in the protection circuit on the DC side of the photovoltaic system exceeds the set threshold of the TVS diode, so as to protect other components in the circuit.

9. The energy storage simulation system according to claim 1, wherein The protection circuit on the AC side includes: A varistor, a gas discharge tube and a Y capacitor, wherein the varistor is used to protect electrical equipment and prevent continuous current from being generated when the gas discharge tube discharges, and the Y capacitor is a three-terminal capacitor.

10. An analysis method based on a simulation model, characterized in that, It includes: Set the system parameters of the photovoltaic system and the energy storage device in the simulation model, wherein the simulation model includes: a photovoltaic system sub-model, an energy storage device sub-model and a power grid simulation sub-model, the energy storage device is connected to the grid connection point on the grid side, and the system parameters include a power curve, battery capacity, voltage, current; Connect the photovoltaic system sub-model and the energy storage device sub-model through a universal bridge module and connect them to the power grid simulation sub-model; Apply a PID controller to control the output power of the energy storage device, and maintain the power at the grid connection point within a set range by compensating the power curve of the photovoltaic system; Execute the simulation start command, simulate the grid regulation strategy, and collect simulation data, wherein the grid regulation strategy includes: when the power generated by the photovoltaic system is greater than the power demand on the grid side, control the energy storage device to charge to consume the redundant power of the photovoltaic system, and when the power generated by the photovoltaic system is less than the power demand on the grid side, control the energy storage device to discharge to the grid side to meet the insufficient power demand on the grid side, wherein the simulation data includes the power curve of the photovoltaic system, the power curve of the energy storage device, voltage and current parameters; Control an oscilloscope to collect the waveforms at both ends of the photovoltaic system, the energy storage device and the grid connection point to obtain simulation waveforms; Based on the simulation waveforms and the simulation data, evaluate the grid connection performance and resource utilization rate of the energy storage simulation system, and output a simulation report.

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