DC micro-grid control method and device, electronic equipment and storage medium

Abstract

The invention provides a control method and device of a direct-current micro-grid, electronic equipment and a storage medium. The control mode comprises the following steps: acquiring a state value of any hybrid energy storage system at the current moment and a state value of any hybrid energy storage system at the last moment; and when the difference value between the state values of the current moment and the last moment of any hybrid energy storage system is greater than a preset value delta, adjusting the voltage, the current and the virtual resistance of all the hybrid energy storage systems. Therefore, all hybrid energy storage systems can be effectively coordinated, and the stability of the DC micro-grid is maintained.

Description

Technical Field

[0001] The present invention relates to the field of new energy technologies, and in particular to a control method, device, electronic equipment and storage medium for a direct current microgrid. Background Art

[0002] With the development of renewable energy technology and the modernization of power systems, DC microgrids are gaining more and more attention due to their high efficiency and simplified power conversion process. Figure 1 As shown, a DC microgrid generally includes energy management of multiple hybrid energy storage systems (HESS), which generally include: batteries or supercapacitors, each of which is connected to the DC bus through a DC-DC converter. In addition, photovoltaic panels, wind power generation equipment, and DC loads can also be electrically connected to the DC bus.

[0003] In a DC microgrid, effective coordination between multiple hybrid energy storage systems is required because the DC microgrid must be able to respond quickly to load changes and source changes to maintain the stability of the grid. Summary of the invention

[0004] The object of the present invention is to provide a control method, device, electronic equipment and storage medium for a DC microgrid.

[0005] In order to achieve one of the above-mentioned objects of the invention, an embodiment of the present invention provides a control method for a DC microgrid, wherein the DC microgrid includes Num hybrid energy storage systems HESS1, HESS2, ..., HESS Num , and DC bus, in any hybrid energy storage system HESS i Each HESS system includes a battery or a super capacitor, and the battery or super capacitor is electrically connected to the DC bus through a DC-DC converter. i can directly communicate with the other hybrid energy storage systems; wherein i is a natural number, 1≤i≤Num; comprising the following steps: obtaining any hybrid energy storage system HESS i The state value x at the current time t i (t), and the state value x at the previous moment i (t-1); calculate f i (t)=||x i (t)-x i (t-1)|| 2 -δ, when any f i When (t)>0, the hybrid energy storage system HESS i Voltage Hybrid Energy Storage System HESSi The current value of the voltage I i Increase Among them, a ij and b ij are control coefficients, N i It is a hybrid energy storage system HESS i The set of hybrid energy storage systems with direct communication links, δ is a constant, |||| is the norm, δ>0; adjust the hybrid energy storage system HESS i The virtual resistance R vi , so that Among them, V ref is the preset reference voltage.

[0006] As a further improvement of an embodiment of the present invention, the state value x i (t)Including voltage.

[0007] As a further improvement of an embodiment of the present invention, the state value x i (t) includes current.

[0008] The embodiment of the present invention further provides a control device for a DC microgrid, wherein the DC microgrid includes Num hybrid energy storage systems HESS1, HESS2, ..., HESS Num , and DC bus, in any hybrid energy storage system HESS i Each HESS system includes a battery or a super capacitor, and the battery or super capacitor is electrically connected to the DC bus through a DC-DC converter. i can directly communicate with other hybrid energy storage systems; where i is a natural number, 1≤i≤Num; includes the following modules: an information acquisition module, used to obtain any hybrid energy storage system HESS i The state value x at the current time t i (t), and the state value x at the previous moment i (t-1); processing module, used to calculate f i (t)=||x i (t)-x i (t-1)|| 2 -δ, when any f i When (t)>0, the hybrid energy storage system HESS i Voltage Hybrid Energy Storage System HESS i The current value of the voltage I i Increase Among them, a ij and b ij are control coefficients, N iIt is a hybrid energy storage system HESS i The set of hybrid energy storage systems with direct communication links, δ is a constant, |||| is the norm, δ>0; adjust the hybrid energy storage system HESS i The virtual resistance R vi , so that Among them, V ref is the preset reference voltage.

[0009] As a further improvement of an embodiment of the present invention, the state value x i (t)Including voltage.

[0010] As a further improvement of an embodiment of the present invention, the state value x i (t) includes current.

[0011] An embodiment of the present invention further provides an electronic device, comprising: a memory for storing executable instructions; and a processor for implementing the above-mentioned control method when executing the executable instructions stored in the memory.

[0012] The embodiment of the present invention further provides a storage medium storing executable instructions for causing a processor to execute the above control method.

[0013] Compared with the prior art, the technical effect of the present invention is that: the embodiment of the present invention provides a control method, device, electronic device and storage medium of a DC microgrid, and the control method includes the following steps: obtaining the state value of any hybrid energy storage system at the current moment and the state value at the last moment; when the difference between the state value of any hybrid energy storage system at the current moment and the last moment is greater than the preset value δ, adjusting the voltage, current and virtual resistance of all hybrid energy storage systems. Thus, all hybrid energy storage systems can be effectively coordinated to maintain the stability of the DC microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a structural diagram of a DC microgrid in an embodiment of the present invention;

[0015] Figure 2 It is a flow chart of a control method of a DC microgrid in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below in conjunction with the various embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0017] As used herein, terms indicating spatial relative positions such as "upper," "above," "lower," and "below" are used for the purpose of convenience to describe the relationship of one unit or feature relative to another unit or feature as shown in the accompanying drawings. Terms of spatial relative position may be intended to include different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if the device in the figure is turned over, units described as being "below" or "beneath" other units or features will be located "above" the other units or features. Thus, the exemplary term "below" can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein interpreted accordingly.

[0018] Embodiment 1 of the present invention provides a control method for a DC microgrid, wherein the DC microgrid includes Num hybrid energy storage systems HESS1, HESS2, ..., HESS Num , and DC bus, in any hybrid energy storage system HESS i Each HESS system includes a battery or a super capacitor, and the battery or super capacitor is electrically connected to the DC bus through a DC (Direct Current)-DC converter. i They can all establish direct communication links with the remaining hybrid energy storage systems; where i is a natural number, 1≤i≤Num; here, the battery is mainly responsible for storing and providing a large capacity of electrical energy, the battery can continuously supply power for a long time, and the battery type can be lead-acid battery, lithium-ion battery, etc. Supercapacitor is an energy storage element, mainly used for fast charging and discharging. It is characterized by high power density, the ability to quickly respond to load changes, and provide instantaneous large current. Supercapacitors are usually used to smooth power fluctuations and handle short-term high power demands. In addition, photovoltaic panels, wind power generation equipment, etc. can also be set in the DC microgrid, and photovoltaic panels and wind power generation equipment are also electrically connected to the DC bus through a DC-DC converter.

[0019] In the power system, a dynamic balance is achieved between the power to be supplied and the power consumed. For DC microgrids, power balance includes the following meanings: (1) The balance between the power supply and the power demand, that is, the balance between the power provided by batteries and supercapacitors and the power consumed by the load; (2) At any time, batteries and supercapacitors must be able to provide enough power to meet the load demand. If the power supply is insufficient, the voltage will drop and may even cause a power outage; if the power supply is excessive, the voltage will rise and may damage the load; (3) Batteries and supercapacitors can store energy when there is excess power and release energy when there is insufficient power to maintain power balance. In addition, batteries have a high energy density and are suitable for long-term energy storage and release, but their response speed is relatively slow; batteries are mainly responsible for providing power for the basic load to ensure long-term power balance. Supercapacitors have a high power density and can respond quickly to load changes. They are suitable for handling instantaneous power demand and short-term energy storage; supercapacitors are mainly used to smooth load fluctuations, respond quickly to power mutations, and ensure instantaneous power balance. The purpose of this control method is to achieve a dynamic balance between the power supplied and the power consumed by the DC microgrid.

[0020] Here, each hybrid energy storage system HESS i can establish direct communication links with a number of hybrid energy storage systems. It can be understood that Num hybrid energy storage systems HESS1, HESS2, ..., HESS Num Constitute a sparse communication network. A sparse communication network is a communication network structure in which the communication connections between nodes (i.e., hybrid energy storage systems) are limited and selective, rather than comprehensive and dense. Specifically, in a sparse communication network, each node communicates only with a limited number of other nodes, rather than maintaining connections with all other nodes. Characteristics of sparse communication networks: (1) Limited connections. Each node only communicates directly with a small number of other nodes, rather than with all nodes in the network. This limited connection structure greatly reduces the communication burden and complexity; (2) Efficiency. Due to the reduction in the number of communication connections, the communication efficiency in the network is higher, and the communication delay and bandwidth occupancy are also significantly reduced; (3) Scalability. Sparse communication networks are easier to expand because adding new nodes only requires establishing a limited number of connections, which will not significantly increase the complexity of the network; (4) Robustness. Even if some connections fail, the sparse communication network can still maintain the communication function of most nodes, improving the robustness and reliability of the system.

[0021] like Figure 2 As shown, the following steps are included:

[0022] Step 201: Obtain any hybrid energy storage system HESS i The state value x at the current time t i (t), and the state value x at the previous moment i (t-1); Here, all hybrid energy storage systems HESS1, HESS2, ..., HESS can be obtained at a preset time interval. Num The state value x i (t); state value x i (t) can be multiple specific states, such as voltage and current.

[0023] Step 202: Calculate f i (t)=||x i (t)-x i (t-1)|| 2 -δ, when any f i When (t)>0, the hybrid energy storage system HESS i Voltage Hybrid Energy Storage System HESS i The current value of the voltage I i Increase Among them, a ij and b ij are control coefficients, N i It is a hybrid energy storage system HESS i The set of hybrid energy storage systems with direct communication links, δ is a constant, |||| is the norm, δ>0; adjust the hybrid energy storage system HESS i The virtual resistance R vi , so that Among them, V ref is the preset reference voltage.

[0024] Here, when the load suddenly changes (for example, the load suddenly increases or decreases), or when the output of photovoltaic panels or wind power generation equipment changes significantly, or when other equipment fails, it will cause f i (t)>0.

[0025] Here, virtual resistance is a method of simulating resistance characteristics through control algorithms. It is widely used in the control of power systems, especially microgrids. It is not an actual physical resistance, but a parameter simulated by software or controllers to adjust the voltage and current relationship of the system. The main functions of virtual resistance are: (1) regulating power distribution. By adjusting the size of virtual resistance, the power distribution between different energy storage units can be controlled, making the energy management of the entire system more optimized; (2) stabilizing system operation. Virtual resistance can help alleviate voltage and current fluctuations in the system and improve system stability.

[0026] Here, in order to ensure the stability and power balance of the entire system, it is necessary to use a distributed control algorithm to adjust the voltages of each hybrid energy storage system so that they tend to be consistent, thereby avoiding excessive voltage deviations. The output current of each unit can be dynamically allocated to achieve optimized power distribution.

[0027] In a DC microgrid, each hybrid energy storage system (including batteries and supercapacitors) is connected to the DC bus through a DC-DC converter. The sparse communication network communicates with each hybrid energy storage system to adjust its output voltage and current.

[0028] Based on Lyapunov stability theory, the event-triggered control strategy is designed to trigger when specific conditions are met. Among them, ∈ is a positive constant, and V(x) is a Lyapunov function, which is used to measure the stability of the system state x. The Lyapunov function is usually a positive definite function, that is, V(x) ≥ 0, and at the equilibrium point x = 0, V(x) = 0. represents the rate of change of the Lyapunov function over time. The sign of can be used to determine the stability of the system. Then the Lyapunov function V(x) will decrease over time, indicating that the system tends to a stable state. x is the state vector of the system at the current moment, including the system voltage V i 、Current I i And other parameters. last is the state vector of the system at the last control and communication update. The parameter ∈ is a positive constant used to adjust the sensitivity of the trigger condition. Usually, the value of ∈ is small to ensure that the control update is triggered only when the change in the system state is significant enough.

[0029] Trigger condition formula: ∥xx last ∥ 2 Indicates the current state x and the last updated state xlast The difference between Less than -∈∥xx last ∥ 2 , triggers control update.

[0030] In this embodiment, the state value x i (t) Specifically includes: voltage or current.

[0031] In the invention practice of the inventor, the following experiments were conducted:

[0032] An islanded DC microgrid model containing multiple hybrid energy storage systems is constructed. Each HESS includes a battery and a supercapacitor, which are connected to the DC bus through a power electronic converter. The overall configuration of the microgrid is as follows: (1) Reference voltage V ref : 220V; (2) Line resistance R line : Set to 0.10, 0.12, 0.14Ω respectively; (3) Virtual resistance Rv: Dynamically adjusted based on battery SOC.

[0033] Simulation Example

[0034] (1) Basic operation and control verification: At the beginning of the simulation, the initial SOC of the three groups of HESS were set to simulate different starting energy states. By setting the droop control and distributed control layer parameters, the simulation operation simulated the load mutation and PV output fluctuation.

[0035] (2) Event-triggered control implementation: The event-triggered threshold δ is set to determine when to update the control signal and communicate. The changes in the HESS output voltage and current are monitored in the simulation to verify the responsiveness and accuracy of the control strategy.

[0036] Specific simulation observations

[0037] (1) Load change response: At 1 second, the simulation reduces the initial load by 50%, and the system can quickly adjust the output of each HESS to maintain the bus voltage stability. At this time, event-triggered control effectively reduces the number of communications because the control signal is updated only when necessary.

[0038] (2) Power balance test: At 4 seconds and 7 seconds, the load was added and removed, respectively. It was observed that all HESSs could quickly redistribute power to adapt to load changes based on the set virtual resistance and regulation strategy. Event-triggered control ensured the communication efficiency of this process and reduced unnecessary system burden.

[0039] (2) System stability verification: Throughout the entire simulation process, the system bus voltage and the output of each HESS always remain within the set safety range, which proves the effectiveness and stability of the adopted control strategy and event triggering mechanism.

[0040] Embodiment 2 of the present invention provides a control device for a DC microgrid, wherein the DC microgrid includes Num hybrid energy storage systems HESS1, HESS2, ..., HESS Num , and DC bus, in any hybrid energy storage system HESS i Each HESS system includes a battery or a super capacitor, and the battery or super capacitor is electrically connected to the DC bus through a DC-DC converter. i can directly communicate with other hybrid energy storage systems; where i is a natural number, 1≤i≤Num; includes the following modules: an information acquisition module, used to obtain any hybrid energy storage system HESS i The state value x at the current time t i (t), and the state value x at the previous moment i (t-1); processing module, used to calculate f i (t)=||x i (t)-x i (t-1)|| 2 -δ, when any f i When (t)>0, the hybrid energy storage system HESS i Voltage Hybrid Energy Storage System HESS i The current value of the voltage I i Increase Among them, a ij and b ij are control coefficients, N i It is a hybrid energy storage system HESS i The set of hybrid energy storage systems with direct communication links, δ is a constant, |||| is the norm, δ>0; adjust the hybrid energy storage system HESS i The virtual resistance R vi , so that Among them, V ref is the preset reference voltage.

[0041] In this embodiment, the state value x i (t)Including voltage.

[0042] In this embodiment, the state value x i (t) includes current.

[0043] A third embodiment of the present invention provides an electronic device, comprising: a memory for storing executable instructions; and a processor for implementing the control method in the first embodiment when executing the executable instructions stored in the memory.

[0044] Embodiment 4 of the present invention provides a storage medium storing executable instructions for causing a processor to execute and implement the control method in embodiment 1.

[0045] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0046] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A control method for a DC microgrid, wherein the DC microgrid comprises Num hybrid energy storage systems HESS1, HESS2, ..., HESS Num , and DC bus, in any hybrid energy storage system HESS i Each HESS system includes a battery or a super capacitor, and the battery or super capacitor is electrically connected to the DC bus through a DC-DC converter. i can establish direct communication links with other hybrid energy storage systems; among them, i is a natural number, 1≤i≤Num; it is characterized by comprising the following steps: Get any hybrid energy storage system HESS i The state value x at the current time t i (t), and the state value x at the previous moment i (t-1); Calculate f i (t)=||x i (t)-x i (t-1)|| 2 -δ, when any f i When (t)>0, the hybrid energy storage system HESS i Voltage Hybrid Energy Storage System HESS i The current value of the voltage I i Increase Among them, a ij and b ij are control coefficients, N i It is a hybrid energy storage system HESS i The set of hybrid energy storage systems with direct communication links, δ is a constant, || || is the norm, δ>0; adjust the hybrid energy storage system HESS i The virtual resistance R vi , so that Among them, V ref is the preset reference voltage.

2. The control method according to claim 1, characterized in that: The state value x i (t)Including voltage.

3. The control method according to claim 1, characterized in that: The state value x i (t) includes current.

4. A control device for a DC microgrid, the DC microgrid comprising Num hybrid energy storage systems HESS1, HESS2, ..., HESS Num , and DC bus, in any hybrid energy storage system HESS i Each HESS system includes a battery or a super capacitor, and the battery or super capacitor is electrically connected to the DC bus through a DC-DC converter. i can establish direct communication links with other hybrid energy storage systems; among them, i is a natural number, 1≤i≤Num; it is characterized by comprising the following modules: Information acquisition module, used to obtain any hybrid energy storage system HESS i The state value x at the current time t i (t), and the state value x at the previous moment i (t-1); Processing module, used to calculate f i (t)=||x i (t)-x i (t-1)|| 2 -δ, when any f i When (t)>0, the hybrid energy storage system HESS i Voltage Hybrid Energy Storage System HESS i The current value of the voltage I i Increase Among them, a ij and b ij are control coefficients, N i It is a hybrid energy storage system HESS i The set of hybrid energy storage systems with direct communication links, δ is a constant, || || is the norm, δ>0; adjust the hybrid energy storage system HESS i The virtual resistance R vi , so that Among them, V ref is the preset reference voltage.

5. The control device according to claim 4, characterized in that: The state value x i (t)Including voltage.

6. The control device according to claim 4, characterized in that: The state value x i (t) includes current.

7. An electronic device, characterized in that: include: A memory for storing executable instructions; A processor, configured to implement the control method according to any one of claims 1 to 3 when executing the executable instructions stored in the memory.

8. A storage medium, characterized in that: Executable instructions are stored, which are used to cause the processor to execute and implement the control method described in any one of claims 1 to 3.

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