Power grid new energy unit and energy storage coordinated switching control method

Abstract

The invention discloses a power grid new energy unit and energy storage coordinated switching control method, and belongs to the technical field of power system operation and control, and the method comprises the steps: detecting the dynamic voltage of each bus in a power grid through a two-stage hierarchical control structure based on a multi-agent system and built in the power grid in advance; calculating a moving average value of each bus voltage based on the detected dynamic voltage; calculating the difference percentage between the actual voltage and the moving average value through the moving average value and the actual voltage measured in advance; calculating a voltage stability risk index based on the difference percentage between the actual voltage and the moving average value; according to the method, renewable energy sources can be utilized to the maximum extent to provide high-quality electric power so as to meet the requirement for safe operation of the system, an energy storage system is effectively utilized to overcome the defect of insufficient electric power, and the energy storage system can be used for providing high-quality electric power to meet the requirement for safe operation of the system. And the economic benefit of operation is effectively ensured.

Description

Technical Field

[0001] The invention relates to a method for coordinated switching control of a new energy generator set and energy storage in a power grid, belonging to the technical field of power system operation and control. Background Art

[0002] In recent years, green and low-carbon energy construction has received widespread attention worldwide. At the same time, the drawbacks of traditional power supply modes have also been exposed. Therefore, there is a lot of room for the use of power grids that adopt renewable energy power generation technology. The power grid generally consists of a group of loads, energy storage devices, and some multi-power sources. Since the power grid contains multiple types of power generation components and energy storage devices, the terminals of the system are much more complex than traditional power grids, and the interactions between them usually reflect more complex hybrid dynamic behaviors. Since the output power of power sources including photovoltaics and wind power is highly dependent on the random natural environment, they often provide intermittent and random power delivery. Therefore, it is very necessary for the power grid to provide flexible and reliable control strategies. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for coordinated switching control of new energy units and energy storage in a power grid, so as to maximize the use of renewable energy to provide high-quality electricity to meet the needs of safe operation of the system, effectively utilize the energy storage system to fill the power shortage defect, and effectively ensure the economic benefits of its operation.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0005] In a first aspect, the present invention provides a method for coordinated switching control of a new energy generating unit and energy storage in a power grid, comprising:

[0006] Through the two-level hierarchical control structure based on the multi-agent system pre-built in the power grid, the dynamic voltage of each bus in the power grid is detected;

[0007] Based on the detected dynamic voltage, a moving average value of each bus voltage is calculated;

[0008] Calculate the difference percentage between the actual voltage and the moving average value by using the moving average value and the actual voltage measured in advance;

[0009] Calculate the voltage stability risk index based on the percentage difference between the actual voltage and the moving average;

[0010] Whether the voltage is stable is determined according to the voltage stability risk indicator, and if the voltage is unstable, a coordinated switching control instruction is triggered.

[0011] Furthermore, the power grid includes different types of power sources and various energy storage devices, wherein the energy storage devices include batteries for long-term energy, supercapacitors and flywheels for rapid dynamic power regulation, and the power sources and energy storage devices are capable of operating in different modes according to the climate conditions they constrain or the power changes required by the system.

[0012] Furthermore, the two-level hierarchical control structure includes an upper-level coordination control layer of the power grid and a lower-level unit control layer. The upper-level coordination control layer includes a power grid central controller, which is used to generate discrete instructions according to unstable areas of the power grid voltage and send them to the lower-level unit control layer. The lower-level unit control layer includes a power supply intelligent agent, an energy storage intelligent agent, a public power grid intelligent agent and a load intelligent agent, which are used to switch modes according to the discrete instructions of the upper-level coordination control layer.

[0013] Furthermore, the moving average value of each bus voltage is calculated based on the detected dynamic voltage, including:

[0014] The dynamic voltage of the i-th bus in the power grid To test, the formula is as follows: (1); in, is the voltage of the i-th node at the n-th moment, T represents the matrix transposition operation;

[0015] Calculate the moving average of the N available measurements obtained by the i-th node at the j-th time The formula is as follows:

[0016] (2);

[0017] in, is the voltage of the ith node at the kth moment, and N and M are the number of available measurements.

[0018] Furthermore, the voltage stability risk index is calculated based on the difference percentage between the actual voltage and the moving average value, including:

[0019] Calculate the percentage difference between the actual voltage measured at node i and the moving average at the jth moment The formula is as follows:

[0020] (3);

[0021] in, is the actual voltage of the i-th node at the j-th moment;

[0022] Calculate the i-th bus voltage stability risk index at time j by using the difference percentage , the formula is as follows:

[0023] (4);

[0024] in, / The percentage difference between the measured voltage at node i and the moving average at time k / k+1.

[0025] Further, judging whether the voltage is stable according to the voltage stability risk indicator includes: setting a safe voltage threshold as ,like , the voltage is unstable; if , the voltage is stable.

[0026] Furthermore, the lower unit control layer includes a new energy wind power unit, a photovoltaic unit unit, and an energy storage unit, and the new energy wind power unit, the photovoltaic unit unit, and the energy storage unit are established through a fuzzy Petri net model.

[0027] Furthermore, the coordinated switching control instruction includes:

[0028] Instruction 1: Switch the energy storage unit to charging mode and stop the previous discharging mode;

[0029] Instruction 2: Switch the energy storage unit to discharge mode;

[0030] Instruction 3: Switch the supercapacitor and flywheel to charging mode;

[0031] Instruction 4: Switch the supercapacitor and flywheel to discharge mode;

[0032] Instruction 5: Request the fuel cell to switch to the start mode;

[0033] Instruction 6: Request the fuel cell to switch to standby mode;

[0034] Instruction 7: Force non-critical load units to switch to load shedding mode;

[0035] Directive 8: Requires grid agents to operate in island mode;

[0036] Instruction 9: Request the grid agent to access the main grid.

[0037] Furthermore, the method further comprises:

[0038] When the upper coordination control layer detects a fault in the upper power grid close to the alarm value, the central controller of the power grid starts the decoupling mode token and controls the inverters of the lower units that inject power into the power grid in sequence. The control instructions of the upper coordination control layer are based on the voltage stability domain of all nodes. Energy management is determined by system power balance. The formula is as follows:

[0039] (9);

[0040] in, and are wind power and photovoltaic power respectively. is the power required by the local load, Indicates the amount of load, is the discharge power of the energy storage, is the fuel cell power, It is the signal of the working mode of the energy storage unit. If it is equal to 0, the discharge mode is activated, otherwise, the charging mode is activated;

[0041] When the public power grid fluctuates, the system operates stably, and the grid control center monitors whether the frequency and voltage of the grid are equal to the mains grid, and then sends instructions to it9;

[0042] When the upper coordination control layer detects that the power grid is approaching the threshold, it sends instructions to the lower unit control layer 8. The control inputs of each stage are as follows:

[0043] (10);

[0044] (11);

[0045] (12);

[0046] (13);

[0047] in, It is the control input when the power provided by the power system is greater than the power required by the local load. It is the control input when the power provided by the power system is less than the power required by the local load. It is the control input when the power provided by the power system and the battery is less than the power required by the local load. It is the control input when the power provided by the power system and energy storage device is less than the power required by the local load. For the power system control input, and The power provided by the power system and the power required by the local load are respectively, For battery control input, is the battery power, It is the control input of the energy storage device. It is the fuel cell control input;

[0048] In the fuzzy Petri net model, the new energy wind power unit and photovoltaic unit are operated in the maximum power point tracking mode. At this time, the control input of the wind power and photovoltaic inverters are connected to the grid bus, and the power source agent transfers energy to the energy storage agent.

[0049] The upper coordination control layer determines that the grid output power satisfies formula (11), and then sends instruction 1 to the energy storage agent, making it equal to 1. The priority of energy storage depends on the following formula:

[0050] (14);

[0051] in, , is the state of charge of the energy storage at time m and i, n2 is the number of moments, is the ratio of the current energy storage state to all states. The larger the ratio, The higher the value;

[0052] If the additional power from wind and photovoltaic power exceeds the battery capacity The upper coordination control layer sends instruction 3 to the supercapacitor and flywheel and instruction 2 to the energy storage agent according to the condition that the output power of wind power and photovoltaic power reaches formula (12). The multi-agent system Set to 0 to activate the fuzzy Petri net model, and the following two situations occur:

[0053] (a) , is the discharge power of the energy storage at time k, and the upper coordination control layer sends instruction 1 to the energy storage agent at the minimum value;

[0054] (b) , which is the critical state of formula (13). The upper coordination control layer sends instructions 4 and 6 to the relevant agents according to the priority. Through formula (14), if the power shortage persists or reaches the warning value, the next token will be activated. Finally, the multi-agent system switches the standby mode of the fuel cell to the start-up mode;

[0055] When the output power of all generators meets the load consumption, they are switched to the pause output mode in sequence according to the priority of instructions 6, 3 and 1;

[0056] when Exceed , the grid output power cannot meet the load demand, the system When the safety threshold is exceeded and the grid cannot carry all the loads, the upper coordination control layer will send instructions 7 to the non-critical load agents to adapt the critical loads to operate in the normal operation mode;

[0057] When the power grid becomes stable, the multi-agent system detects the information and receives the quotation from the lower unit control layer, the power grid reaccepts the non-critical load that was previously cut off, and then sends instructions 9 to the local agent to reconnect it to the grid as a load.

[0058] In a second aspect, the present invention provides a coordinated switching control device for a power grid new energy unit and energy storage, comprising:

[0059] A detection module is used to detect the dynamic voltage of each bus in the power grid through a two-level hierarchical control structure based on a multi-agent system pre-built in the power grid;

[0060] A first calculation module, used for calculating a moving average value of each bus voltage based on the detected dynamic voltage;

[0061] A second calculation module, used for calculating the difference percentage between the actual voltage and the moving average value by using the moving average value and the actual voltage measured in advance;

[0062] a third calculation module, for calculating a voltage stability risk index based on a difference percentage between the actual voltage and the moving average value;

[0063] The switching control module is used to determine whether the voltage is stable according to the voltage stability risk indicator, and trigger a coordinated switching control instruction if the voltage is not stable.

[0064] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the aforementioned methods.

[0065] In a fourth aspect, the present invention provides a computer device, comprising:

[0066] Memory, for storing computer programs / instructions;

[0067] A processor is used to execute the computer program / instructions to implement the steps of any of the aforementioned methods.

[0068] In a fifth aspect, the present invention provides a computer program product, comprising a computer program / instruction, which implements the steps of any of the aforementioned methods when executed by a processor.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] (1) The two-level hierarchical control architecture based on a multi-agent system proposed in this invention can effectively solve the complex switching control problems of various operating modes of power supply and energy storage systems.

[0071] (2) The present invention develops a voltage safety assessment index that can well characterize the impact of different power supply units on the voltage in the power quality when they are connected to the power grid, so as to support the implementation of coordinated control instructions.

[0072] (3) The present invention proposes an energy management strategy for switching the operating modes of each unit to cope with the uncertainty and emergency situations of the power grid operating environment, effectively ensuring the safety of system operation and providing an efficient and safe power source for local loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 It is a flow chart of a method for coordinated switching control of a power grid new energy unit and energy storage provided by an embodiment of the present invention;

[0074] Figure 2 is a two-level hierarchical control structure diagram based on a multi-agent system provided by an embodiment of the present invention;

[0075] Figure 3 It is a basic structure diagram of a power grid provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0076] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0077] Embodiment 1: This embodiment introduces a method for coordinated switching control of a new energy generating unit and energy storage in a power grid, including:

[0078] Through the two-level hierarchical control structure based on the multi-agent system pre-built in the power grid, the dynamic voltage of each bus in the power grid is detected;

[0079] Based on the detected dynamic voltage, a moving average value of each bus voltage is calculated;

[0080] Calculate the difference percentage between the actual voltage and the moving average value by using the moving average value and the actual voltage measured in advance;

[0081] Calculate the voltage stability risk index based on the percentage difference between the actual voltage and the moving average;

[0082] Whether the voltage is stable is determined according to the voltage stability risk indicator, and if the voltage is unstable, a coordinated switching control instruction is triggered.

[0083] like Figure 1 As shown, the application process of the coordinated switching control method between the new energy generating set and the energy storage provided in this embodiment specifically involves the following steps:

[0084] (1) Build a two-level hierarchical control structure based on a multi-agent system;

[0085] (2) Develop voltage safety assessment indicators to support the implementation of coordinated switching instructions;

[0086] (3) Propose an energy management strategy for switching the operating modes of each unit to cope with the uncertainty and emergency situations of the power grid operating environment.

[0087] The specific steps include:

[0088] Step 1: Build a two-level hierarchical control structure based on a multi-agent system. In this embodiment, Figure 2 The two-level hierarchical control structure diagram based on the multi-agent system shown in Figure 3 The basic structure diagram of the power grid shown in the figure, the control architecture involves the upper coordination control layer and the lower unit control layer of the power grid, wherein the power grid includes different types of power sources and various energy storage devices, the energy storage devices include batteries for long-term energy, supercapacitors and flywheels for fast dynamic power regulation, the power sources and energy storage devices can operate in different modes according to the climatic conditions they restrict or the power changes required by the system, the control interface of the load and the micro source is responsible for controlling the corresponding units according to the instructions of the upper coordination control layer to meet the power balance requirements; the power grid central controller belongs to the upper coordination control layer, it can switch the discrete mode of the lower unit according to the unstable area of ​​the power grid voltage, the lower unit control layer can control the component units to provide the required heat and electricity for local users, wherein the lower unit control layer includes power source intelligent body, energy storage intelligent body, public grid intelligent body and load intelligent body, it can formulate continuous control strategy according to the discrete instruction switching mode of the upper coordination control layer.

[0089] Step 2: Develop voltage safety assessment indicators to support the implementation of coordinated switching instructions;

[0090] First, by calculating the dynamic voltage of the i-th bus in the power grid Carry out the test, as follows:

[0091] (1);

[0092] in, is the voltage of the i-th node at the n-th moment, T represents the matrix transposition operation;

[0093] Calculate the moving average of the N available measurements obtained by the i-th node at the j-th time It can be described as:

[0094] (2);

[0095] in, is the voltage of the ith node at the kth moment, N, M are the available measurement numbers;

[0096] Then, the percentage difference between the voltage and the moving average at the jth moment is measured for:

[0097] (3);

[0098] in, is the actual voltage of the i-th node at the j-th moment;

[0099] The i-th bus voltage stability risk index at time j It can be expressed as the area under the percent diversity curve divided by N:

[0100] (4);

[0101] in, / The percentage difference between the measured voltage of node i and the moving average at the k / k+1th moment;

[0102] If the environment changes suddenly, the power grid will be greatly disturbed, and the voltage may exceed the warning value. The safety voltage threshold is defined as ,like , the voltage is unstable; if , the voltage is stable.

[0103] Step 3: Propose an energy management strategy for switching the operating modes of each unit to cope with the uncertainty and emergency situations of the power grid operating environment;

[0104] After a large disturbance occurs, logical coordination control commands are executed according to the voltage stability risk index. Based on multi-agent system technology, the upper coordination control layer detects all busbars in real time and makes appropriate judgments or switching instructions when a certain point approaches the critical value, and then sends control commands to the lower unit control layer, thereby achieving the best balance between supply and demand and maintaining stable system operation.

[0105] Among them, the lower unit control layer mainly includes new energy wind power, photovoltaic units, energy storage and other units. The smooth switching model between their discrete states is established by fuzzy Petri nets. Based on the fuzzy Petri net theory, each discrete node represents the state of the agent. In the fuzzy Petri net model of each unit, the token is used to represent the working state of the place. Once the threshold of a token meets the critical condition, the next token will be activated.

[0106] Since the wind power and photovoltaic units of the power grid are susceptible to the serious impact of random and intermittent environments, they always operate in the maximum power point tracking mode when they start working. In this mode, the power required by the power grid is tracked mainly by adjusting the output voltage and current of the new energy units added to the system. Here, a two-power system is used as an example. Based on Kirchhoff's voltage and current laws, its differential equations are as follows:

[0107] (6);

[0108] (7);

[0109] Where d is the differential symbol, and are the currents of the power system and unit j respectively, and denote the inductance and capacitance of unit j respectively, is the voltage of cell j, is the loss of the inverter of unit j, and denote the voltages of the power system and unit j respectively;

[0110] It is then converted into the state equation as shown below:

[0111] (8);

[0112] in, , represents the state matrix, represents the input matrix, , represents the output matrix, represents the feedforward matrix, represents the capacitance and in the power system j, , represents the state vector of unit j, is the current of unit n, represents the control input of unit j, Output vector for unit j; however, considering the operating cost of the new energy unit, fuel cells and energy storage units are used to supplement it. Therefore, the multi-agent system mainly switches the operating mode of the energy storage device according to the load change. The specific design of the control instructions of the lower-level energy storage intelligent unit is as follows:

[0113] Instruction 1: Switch the energy storage unit to charging mode to save extra energy and stop the previous discharging mode;

[0114] Instruction 2: Switch the energy storage unit to discharge mode to provide the missing power and increase its power output;

[0115] Instruction 3: Switch the supercapacitor and flywheel to charging mode to save a lot of power beyond the supercapacitor ;

[0116] Instruction 4: Switch the supercapacitor and flywheel to discharge mode to prevent the battery from over- ;

[0117] Directive 5: Requires the fuel cell to switch to start-up mode to provide the insufficient power of the power supply and energy storage device;

[0118] Instruction 6: Request the fuel cell to switch to standby mode;

[0119] Directive 7: Force non-critical load units to switch to load shedding mode to maintain normal operation of critical loads;

[0120] Directive 8: Requires grid agents to operate in island mode;

[0121] Directive 9: Requires the grid agent to access the main grid;

[0122] In summary, in order to more effectively manage the operation of the power grid, the following energy coordination management strategy is formulated. Specifically:

[0123] When the upper coordination control layer detects a fault in the upper power grid close to the alarm value, the central controller of the power grid starts the decoupling mode token. The lower unit inverter controls the power injected into the power grid in sequence. The control instructions of the upper coordination control layer are based on the voltage stability domain of all nodes. Energy management is mainly judged by system power balance:

[0124] (9);

[0125] in, and are wind power and photovoltaic power respectively. is the power required by the local load, Indicates the amount of load, is the discharge power of the energy storage, is the fuel cell power, It is the signal of the working mode of the energy storage unit. If it is equal to 0, the discharge mode is activated, otherwise, the charging mode is activated;

[0126] 1) When the public power grid fluctuates, the system operates stably. The power grid control center monitors whether the frequency and voltage of the power grid are equal to the mains power grid, and then sends instructions 9 to it. At this time, the power grid is connected to the public grid and operates as a load. The power required by the local load is mainly provided by the power grid;

[0127] 2) When the upper coordination control layer detects that the power grid is close to the threshold, it will send instructions 8 to the lower-level intelligent agents. The power required by the local load can be provided by the power grid alone. During the power supply interval, the energy storage device can fill the gap. The control inputs of each stage are as follows:

[0128] (10);

[0129] (11);

[0130] (12);

[0131] (13);

[0132] in, It is the control input when the power provided by the power system is greater than the power required by the local load. It is the control input when the power provided by the power system is less than the power required by the local load. It is the control input when the power provided by the power system and the battery is less than the power required by the local load. It is the control input when the power provided by the power system and energy storage device is less than the power required by the local load. For the power system control input, and The power provided by the power system and the power required by the local load are respectively, For battery control input, is the battery power, It is the control input of the energy storage device. It is the fuel cell control input;

[0133] In the fuzzy Petri net model, wind power and photovoltaic units are fully operated in maximum power point tracking mode. At this time, the control input of wind power and photovoltaic inverters is connected to the grid bus. Since the output power of wind power and photovoltaic is not controlled, the power source agent transfers energy to the energy storage agent.

[0134] The upper coordination control layer determines that the grid output power satisfies equation (11), and then sends command 1 to the energy storage agent, making it equal to 1. The priority of energy storage depends on the following equation:

[0135] (14);

[0136] in, , is the state of charge of the energy storage at time m and i, n2 is the number of moments, is the ratio of the current energy storage state to all states. The larger the ratio, The higher the value, When the value is low, you should charge it first to extend its life;

[0137] If the additional power from wind and photovoltaic power exceeds the battery capacity , the upper coordination control layer will send command 3 to the supercapacitor and flywheel and command 2 to the energy storage agent based on the information that the output power of wind power and photovoltaic power reaches condition (12). The multi-agent system will Set to 0 to activate the fuzzy Petri net model. Due to the limited discharge capacity of the energy storage unit, its output power can only reach 20% of the total cost, so there will be the following two situations:

[0138] (a) , is the discharge power of the energy storage at time k, and the upper coordination control layer sends command 1 to the energy storage agent at the minimum value;

[0139] (b) , which is the critical state of (13). The upper coordination control layer sends instructions 4 and 6 to the relevant agents according to the priority, such as the supercapacitor agent controlled by the input and the flywheel agent powered by the power supply. Through (14), if the power shortage persists and even reaches the warning value, the next token will be activated. Finally, the multi-agent system switches the standby mode of the fuel cell to the start-up mode;

[0140] When the output power of all generators meets the load consumption, the operation modes of fuel cells, supercapacitors and flywheel units have a polluting effect on gas emissions, service life and cost, so they are switched to the pause output mode in order according to the priority of commands 6, 3 and 1;

[0141] However, as the peak load increases, many power loads need to be powered, which will overload the system and enter a warning state. In order to ensure the safety of the system as much as possible, all generators will be used during the big shock, regardless of other factors;

[0142] when Exceed , the grid output power cannot meet the load demand, the system When the safety threshold is exceeded and the grid cannot carry all the loads, the upper coordination control layer will send instructions 7 to the non-critical load agents to adapt the critical loads to operate in the normal operation mode;

[0143] 3) When the power grid becomes stable and the crisis is over, the multi-agent system detects the information and receives the quotes from the subordinate agents. The power grid can reaccept the non-critical loads that were previously cut off, and then send instructions 9 to the local agents to reconnect them to the grid as loads.

[0144] Embodiment 2: This embodiment provides a coordinated switching control device for a power grid new energy unit and energy storage, including:

[0145] A detection module is used to detect the dynamic voltage of each bus in the power grid through a two-level hierarchical control structure based on a multi-agent system pre-built in the power grid;

[0146] A first calculation module, used for calculating a moving average value of each bus voltage based on the detected dynamic voltage;

[0147] A second calculation module, used for calculating the difference percentage between the actual voltage and the moving average value by using the moving average value and the actual voltage measured in advance;

[0148] a third calculation module, for calculating a voltage stability risk index based on a difference percentage between the actual voltage and the moving average value;

[0149] The switching control module is used to determine whether the voltage is stable according to the voltage stability risk indicator, and trigger a coordinated switching control instruction if the voltage is not stable.

[0150] The specific functional implementation of each of the above modules can be found in the relevant contents of the method in Example 1 and will not be elaborated here.

[0151] Embodiment 3, this embodiment provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of any one of the methods described in Embodiment 1 are implemented.

[0152] Embodiment 4: This embodiment provides a computer device, including:

[0153] Memory, for storing computer programs / instructions;

[0154] A processor, configured to execute the computer program / instructions to implement the steps of any one of the methods described in Example 1.

[0155] Embodiment 5: This embodiment provides a computer program product, including a computer program / instruction, which implements the steps of any method described in Embodiment 1 when executed by a processor.

[0156] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0157] It should be understood by those skilled in the art that the embodiments of the present disclosure may be provided as methods, systems or computer program products. Therefore, the present disclosure may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present disclosure may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0158] The present disclosure is described with reference to flowcharts and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the present disclosure. It should be understood that each process and / or block in the flowchart and / or block diagram and the combination of processes and / or blocks in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0159] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0160] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure rather than to limit its protection scope. Although the present disclosure has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present disclosure, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the disclosed claims to be approved.

Claims

1. A method for coordinated switching control of new energy generating units and energy storage in a power grid, characterized in that: include: Through the two-level hierarchical control structure based on the multi-agent system pre-built in the power grid, the dynamic voltage of each bus in the power grid is detected; Based on the detected dynamic voltage, a moving average value of each bus voltage is calculated; Calculate the difference percentage between the actual voltage and the moving average value by using the moving average value and the actual voltage measured in advance; Calculate the voltage stability risk index based on the percentage difference between the actual voltage and the moving average; Whether the voltage is stable is determined according to the voltage stability risk indicator, and if the voltage is unstable, a coordinated switching control instruction is triggered.

2. The method for coordinated switching control of power grid new energy units and energy storage according to claim 1 is characterized in that: The grid includes different types of power sources and various energy storage devices, including batteries for long-term energy, supercapacitors and flywheels for fast dynamic power regulation. The power sources and energy storage devices can operate in different modes according to the climatic conditions they are subject to or the power changes required by the system.

3. The method for coordinated switching control of power grid new energy units and energy storage according to claim 2 is characterized in that: The two-level hierarchical control structure includes an upper-level coordination control layer of the power grid and a lower-level unit control layer. The upper-level coordination control layer includes a power grid central controller, which is used to generate discrete instructions according to unstable areas of the power grid voltage and send them to the lower-level unit control layer. The lower-level unit control layer includes a power supply intelligent agent, an energy storage intelligent agent, a public power grid intelligent agent and a load intelligent agent, which are used to switch modes according to the discrete instructions of the upper-level coordination control layer.

4. The method for coordinated switching control of power grid new energy units and energy storage according to claim 3 is characterized in that: The step of calculating the moving average of each bus voltage based on the detected dynamic voltage includes: The dynamic voltage of the i-th bus in the power grid To perform the test, the formula is as follows: （1）； in, is the voltage of the ith node at the nth moment, T represents the matrix transposition operation; Calculate the moving average of the N available measurements obtained by the i-th node at the j-th time The formula is as follows: （2）； in, is the voltage of the ith node at the kth moment, and N and M are the number of available measurements.

5. The method for coordinated switching control of power grid new energy units and energy storage according to claim 4 is characterized in that: The voltage stability risk index is calculated based on the difference percentage between the actual voltage and the moving average value, including: Calculate the percentage difference between the actual voltage measured at node i and the moving average at the jth moment The formula is as follows: （3）； in, is the actual voltage of the i-th node at the j-th moment; Calculate the i-th bus voltage stability risk index at time j by using the difference percentage , the formula is as follows: （4）； in, / The percentage difference between the measured voltage at node i and the moving average at time k / k+1.

6. The method for coordinated switching control of power grid new energy units and energy storage according to claim 5 is characterized in that: The step of judging whether the voltage is stable according to the voltage stability risk indicator includes: setting a safe voltage threshold as ,like , the voltage is unstable; if , the voltage is stable.

7. The method for coordinated switching control of power grid new energy units and energy storage according to claim 6 is characterized in that: The lower unit control layer includes a new energy wind power unit, a photovoltaic unit unit, and an energy storage unit, and the new energy wind power unit, the photovoltaic unit unit, and the energy storage unit are established through a fuzzy Petri net model.

8. The method for coordinated switching control of power grid new energy units and energy storage according to claim 7 is characterized in that: The coordinated switching control instruction includes: Instruction 1: Switch the energy storage unit to charging mode and stop the previous discharging mode; Instruction 2: Switch the energy storage unit to discharge mode; Instruction 3: Switch the supercapacitor and flywheel to charging mode; Instruction 4: Switch the supercapacitor and flywheel to discharge mode; Instruction 5: Request the fuel cell to switch to the start mode; Instruction 6: Request the fuel cell to switch to standby mode; Instruction 7: Force non-critical load units to switch to load shedding mode; Directive 8: Requires grid agents to operate in island mode; Instruction 9: Request the grid agent to access the main grid.

9. The method for coordinated switching control of power grid new energy units and energy storage according to claim 8, characterized in that: The method further comprises: When the upper coordination control layer detects a fault in the upper power grid close to the alarm value, the central controller of the power grid starts the decoupling mode token and controls the inverters of the lower units that inject power into the power grid in sequence. The control instructions of the upper coordination control layer are based on the voltage stability domain of all nodes. Energy management is determined by system power balance. The formula is as follows: （9）； in, and are wind power and photovoltaic power respectively. is the power required by the local load, Indicates the amount of load, is the discharge power of the energy storage, is the fuel cell power, It is the signal of the working mode of the energy storage unit. If it is equal to 0, the discharge mode is activated, otherwise, the charging mode is activated; When the public power grid fluctuates, the system operates stably, and the grid control center monitors whether the frequency and voltage of the grid are equal to the mains grid, and then sends instructions to it9; When the upper coordination control layer detects that the power grid is approaching the threshold, it sends instructions to the lower unit control layer 8. The control inputs of each stage are as follows: （10）； （11）； （12）； （13）； in, It is the control input when the power provided by the power system is greater than the power required by the local load. It is the control input when the power provided by the power system is less than the power required by the local load. It is the control input when the power provided by the power system and the battery is less than the power required by the local load. It is the control input when the power provided by the power system and energy storage device is less than the power required by the local load. For the power system control input, and The power provided by the power system and the power required by the local load are respectively, For battery control input, is the battery power, It is the control input of the energy storage device. It is the fuel cell control input; In the fuzzy Petri net model, the new energy wind power unit and photovoltaic unit are operated in the maximum power point tracking mode. At this time, the control input of the wind power and photovoltaic inverters are connected to the grid bus, and the power source agent transfers energy to the energy storage agent. The upper coordination control layer determines that the grid output power satisfies formula (11), and then sends instruction 1 to the energy storage agent, making it equal to 1. The priority of energy storage depends on the following formula: （14）； in, , is the state of charge of the energy storage at time m and i, n2 is the number of moments, is the ratio of the current energy storage state to all states. The larger the ratio, The higher the value; If the additional power from wind and photovoltaic power exceeds the battery capacity The upper coordination control layer sends instruction 3 to the supercapacitor and flywheel and instruction 2 to the energy storage agent according to the condition that the output power of wind power and photovoltaic power reaches formula (12). The multi-agent system Set to 0 to activate the fuzzy Petri net model, and the following two situations occur: (a) , is the discharge power of the energy storage at time k, and the upper coordination control layer sends instruction 1 to the energy storage agent at the minimum value; (b) , which is the critical state of formula (13). The upper coordination control layer sends instructions 4 and 6 to the relevant agents according to the priority. Through formula (14), if the power shortage persists or reaches the warning value, the next token will be activated. Finally, the multi-agent system switches the standby mode of the fuel cell to the start-up mode; When the output power of all generators meets the load consumption, they are switched to the pause output mode in sequence according to the priority of instructions 6, 3 and 1; when Exceed , the grid output power cannot meet the load demand, the system When the safety threshold is exceeded and the grid cannot carry all the loads, the upper coordination control layer will send instructions 7 to the non-critical load agents to adapt the critical loads to operate in the normal operation mode; When the power grid becomes stable, the multi-agent system detects the information and receives the quotation from the lower unit control layer, the power grid reaccepts the non-critical load that was previously cut off, and then sends instructions 9 to the local agent to reconnect it to the grid as a load.

10. A coordinated switching control device for a power grid new energy unit and energy storage, characterized in that: include: A detection module is used to detect the dynamic voltage of each bus in the power grid through a two-level hierarchical control structure based on a multi-agent system pre-built in the power grid; A first calculation module, used for calculating a moving average value of each bus voltage based on the detected dynamic voltage; A second calculation module, used for calculating the difference percentage between the actual voltage and the moving average value by using the moving average value and the actual voltage measured in advance; a third calculation module, for calculating a voltage stability risk index based on a difference percentage between the actual voltage and the moving average value; The switching control module is used to determine whether the voltage is stable according to the voltage stability risk indicator, and trigger a coordinated switching control instruction if the voltage is not stable.

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