Isolated network multi-node voltage control method, device and equipment and storage medium

Abstract

The application discloses a kind of isolated network multi-node voltage control method, device and equipment and storage medium, it is related to voltage control technical field, the isolated network multi-node voltage control method includes: real-time acquisition of the absolute value of reactive power output of network type energy storage unit;Based on preset voltage boundary, reactive power output absolute value iteratively updates the voltage instruction value of each new energy power generation unit in isolated network, wherein, the direction of each iteration update is the direction of making the absolute value of reactive power output of network type energy storage unit decrease;The voltage instruction value of each iteration update is issued to the new energy control unit corresponding to new energy power generation unit, to adjust the absolute value of reactive power output of network type energy storage unit;When the deviation of the current voltage value of each new energy power generation unit and last iteration voltage value meets preset convergence condition, iteration update is terminated.The application can improve the stability of isolated network under voltage disturbance.

Description

Technical Field

[0001] This application relates to the field of voltage control technology, and in particular to a method, apparatus, device, and storage medium for controlling the voltage of multiple nodes in an isolated grid. Background Technology

[0002] In isolated grids, grid-connected energy storage devices have long undertaken the primary task of voltage regulation, resulting in a continuous compression of their reactive power regulation margin and a decline in the system's dynamic support capability to cope with subsequent disturbances. Furthermore, in traditional control methods, the coordinating controller in an isolated grid issues reactive power commands to the grid-connected energy storage devices and various renewable energy generation units to indirectly regulate the voltage at the collection point. However, in multi-node scenarios, if the issued reactive power commands are not configured properly, it can lead to excessive or insufficient reactive power at local nodes, causing problems such as excessive node voltage deviation and resulting in equipment damage. Therefore, improving the stability of isolated grids under voltage disturbances remains a problem that needs to be addressed. Summary of the Invention

[0003] The main objective of this application is to provide a method, apparatus, device, and storage medium for controlling the voltage of multiple nodes in an isolated network, aiming to solve the technical problem of how to improve the stability of an isolated network under voltage disturbances.

[0004] To achieve the above objectives, this application proposes a method for controlling the voltage of multiple nodes in an isolated grid. The method includes: real-time acquisition of the absolute value of reactive power output of a grid-type energy storage unit; iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on a preset voltage boundary and the absolute value of reactive power output, wherein the direction of each iteration update is the direction that reduces the absolute value of reactive power output of the grid-type energy storage unit; sending the voltage command value updated in each iteration to the new energy control unit corresponding to the new energy power generation unit to adjust the absolute value of reactive power output of the grid-type energy storage unit; and terminating the iterative update when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets a preset convergence condition.

[0005] In one embodiment, the step of iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on a preset voltage boundary and the absolute value of the reactive power output includes: obtaining the current absolute value of the reactive power output of the grid-type energy storage unit according to the current voltage command value of the new energy power generation unit in the current iteration cycle; calculating the disturbance absolute value of the reactive power output of the grid-type energy storage unit according to the current voltage command value and a preset disturbance value; and iteratively updating the voltage command value of each new energy power generation unit in the isolated grid according to the current absolute value of the reactive power output, the disturbance absolute value of the reactive power output, and the preset voltage boundary.

[0006] In one embodiment, the step of iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on the current absolute value of reactive power output, the absolute value of disturbance reactive power output, and a preset voltage boundary includes: determining the voltage adjustment direction based on the current absolute value of reactive power output and the absolute value of disturbance reactive power output; calculating candidate voltage command values ​​based on the voltage adjustment direction, the preset iteration step size, and the current voltage command value; and limiting the candidate voltage command values ​​within the preset voltage boundary to obtain the voltage command value updated in this iteration.

[0007] In one embodiment, the step of calculating the absolute value of the disturbance reactive power output of the grid-type energy storage unit based on the current voltage command value and the preset disturbance value includes: superimposing the preset disturbance value onto the current voltage command value to obtain the disturbance voltage command value; performing power flow calculation based on the disturbance voltage command value to obtain the disturbance reactive power output value corresponding to the grid-type energy storage unit; and taking the absolute value of the disturbance reactive power output value to obtain the absolute value of the disturbance reactive power output.

[0008] In one embodiment, the step of terminating the iterative update when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets the preset convergence condition includes: calculating the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration; summing the deviation values ​​of all new energy power generation units to obtain the total voltage deviation; and determining that the preset convergence condition is met and terminating the iterative update when the total voltage deviation is less than or equal to the preset convergence threshold.

[0009] In one embodiment, before the step of real-time acquisition of the absolute value of reactive power output of the grid-type energy storage unit, the method further includes: obtaining the target voltage command value of the convergence point; sending the target voltage command value to the grid-type energy storage unit, and using the target voltage command value as the current voltage command value during the first iteration of the new energy power generation unit.

[0010] In one embodiment, after the steps of iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on the preset voltage boundary and the absolute value of the reactive power output, the method further includes: determining whether a target voltage update command for the collection point is received from the energy management system; when the target voltage update command for the collection point is received, restarting the iterative update of the voltage command value of each new energy power generation unit in the isolated grid according to the target voltage update command for the collection point.

[0011] Furthermore, to achieve the above objectives, this application also proposes a control device for the voltage of multiple nodes in an isolated network. This device includes: a data acquisition module, an iteration module, a data transmission module, and a termination module. Specifically, The acquisition module is used to acquire the absolute value of reactive power output of the grid-type energy storage unit in real time; The iterative module is used to iteratively update the voltage command value of each new energy power generation unit in the isolated grid based on the preset voltage boundary and the absolute value of the reactive power output. The direction of each iteration update is the direction that reduces the absolute value of the reactive power output of the grid-type energy storage unit. The distribution module is used to distribute the voltage command value updated in each iteration to the new energy control unit corresponding to the new energy power generation unit, so as to adjust the absolute value of the reactive power output of the above-mentioned grid-type energy storage unit. The termination module is used to terminate the iterative update when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets the preset convergence condition.

[0012] In addition, to achieve the above objectives, this application also proposes a control device for the voltage of multiple nodes in an isolated grid. The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The computer program is configured to implement the steps of the control method for the voltage of multiple nodes in an isolated grid as described above.

[0013] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the islanded multi-node voltage control method described above.

[0014] In addition, to achieve the above objectives, this application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the islanded multi-node voltage control method described above.

[0015] One or more technical solutions proposed in this application have at least the following technical effects: This application collects the absolute value of reactive power output of the grid-type energy storage unit in real time, which can provide accurate control target feedback for subsequent iterative updates; then, based on the preset voltage boundary and the above-mentioned absolute value of reactive power output, iteratively updates the voltage command value of each new energy power generation unit in the isolated grid, wherein the direction of each iteration update is the direction that reduces the absolute value of reactive power output of the above-mentioned grid-type energy storage unit. By reducing the absolute value of reactive power output of the energy storage, the voltage regulation burden borne by the energy storage can be gradually transferred to the new energy power generation unit, thereby releasing the reactive power capacity occupied in the energy storage unit, so that the energy storage unit... The system provides sufficient reactive power regulation margin under voltage disturbances and constrains the iteratively updated voltage command values ​​within preset voltage boundaries to prevent local voltage exceedances. Each iteratively updated voltage command value is sent to the corresponding renewable energy control unit of the renewable energy generation unit to adjust the absolute value of the reactive power output of the aforementioned grid-connected energy storage unit. Since voltage command values ​​are sent instead of reactive power command values, communication overhead is reduced. Iterative updates terminate when the deviation between the current voltage value of each renewable energy generation unit and the previous iteration's voltage value meets preset convergence conditions. Automatic termination of iteration when the voltage deviation converges to a preset range avoids continuous ineffective adjustments. Ultimately, this improves the stability of the isolated grid under voltage disturbances. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A typical circuit diagram of an islanded multi-node voltage control method provided in the embodiments of this application; Figure 2 A schematic diagram of the overall flow of the islanded network multi-node voltage control method provided in the embodiments of this application; Figure 3 A partial flowchart illustrating the islanded network multi-node voltage control method provided in this application embodiment; Figure 4 A simplified flowchart illustrating the islanded network multi-node voltage control method provided in this application embodiment; Figure 5 A schematic diagram of the module structure of the islanded network multi-node voltage control method provided in the embodiments of this application; Figure 6 A schematic diagram of the device structure of the hardware operating environment for the islanded multi-node voltage control method provided in the embodiments of this application. Detailed Implementation

[0018] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0019] An isolated grid refers to a power grid system that operates independently from the main grid. (See also: [reference needed]) Figure 1 , Figure 1 This is a typical circuit diagram for a multi-node isolated network. Figure 1 This demonstrates a typical multi-node power grid topology operating in islanded mode. The system uses the Point of Common Coupling (PCC) as its core bus, integrating grid-type energy storage devices and multiple renewable energy generation units. Each renewable energy generation unit corresponds to a renewable energy control unit, forming an independently powered microgrid system. The PCC serves as the islanded grid's aggregation point, with the grid-type energy storage devices directly connected to the PCC bus. As the core of voltage and frequency support for the islanded system, it possesses rapid reactive / active / voltage regulation capabilities, providing a stable voltage reference and inertial support for the system.

[0020] New energy power generation unit: The photovoltaic power generation unit and the wind turbine power generation unit are stepped up by a box-type transformer (box-type substation) and then connected to the collection point of the isolated grid via the collection line. The control position of the new energy is generally set on the low-voltage side of the box-type substation. Here, the low-voltage side of the box-type substation is defined as the sub-point of common coupling (SubPCC). This point is the control position of each power generation unit. The sub-PCC can connect multiple power generation units to achieve hierarchical current collection and electrical isolation of each power generation unit. This embodiment takes photovoltaic power generation and wind turbine power generation as examples, but it is not limited to the use of a combination of the two. A single power generation method or other new energy power generation methods can also be used.

[0021] New energy control unit: refers to a control entity that takes SubPCC as the control node and is composed of one or more new energy power generation equipment, inverters / converters, local measurement and control devices and their auxiliary power distribution circuits, and can independently participate in voltage and power regulation.

[0022] Load connection: The load is directly connected to the PCC bus, serving as the main active / reactive demand side of the system, and together with new energy sources and energy storage, it forms an islanded power balance system.

[0023] Network structure: Multiple collector lines connect photovoltaic and wind turbine clusters and PCC respectively, forming a multi-branch radial topology, which can realize independent control and coordinated voltage regulation of each power generation unit.

[0024] In isolated grids, grid-connected energy storage devices have long undertaken the primary task of voltage regulation, resulting in a continuous compression of their reactive power regulation margin and a decline in the system's dynamic support capability to cope with subsequent disturbances. Furthermore, in traditional control methods, the coordinating controller in an isolated grid issues reactive power commands to the grid-connected energy storage devices and various renewable energy generation units to indirectly regulate the voltage at the collection point. However, in multi-node scenarios, if the issued reactive power commands are not configured properly, it can lead to excessive or insufficient reactive power at local nodes, causing problems such as excessive node voltage deviation and resulting in equipment damage. Therefore, improving the stability of isolated grids under voltage disturbances remains a problem that needs to be addressed.

[0025] Therefore, this application provides a method for controlling the voltage of multiple nodes in an isolated grid. By iteratively updating the voltage command value of each new energy power generation unit in the isolated grid, the absolute value of reactive power output of the grid-type energy storage unit is reduced, so that the grid-type energy storage unit has sufficient reactive power regulation margin under voltage disturbances, thereby improving the stability of the isolated grid under voltage disturbances.

[0026] The executing entity in this application embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device capable of performing the above functions, such as a coordination controller for multi-node voltage in an isolated network. The following description uses a coordination controller as an example to illustrate this embodiment and the subsequent embodiments.

[0027] Reference Figure 2 The islanded network multi-node voltage control method provided in Embodiment 1 of this application includes steps S10~S40: Step S10: Real-time acquisition of the absolute value of reactive power output of the grid-type energy storage unit.

[0028] In this embodiment, the grid-type energy storage unit in the isolated grid adopts a voltage / frequency control mode, which can establish its own voltage and frequency references, providing voltage support and inertia response for the isolated grid. Therefore, this embodiment is applicable to isolated grid scenarios, i.e., the system operates in an independent state detached from the main grid, and the system contains at least one grid-type energy storage unit, multiple distributed renewable energy generation units, and corresponding loads. Reactive power output refers to the current reactive power output value of the grid-type energy storage unit. Since reactive power is directional, a positive value indicates that the energy storage sends reactive power to the grid, and a negative value indicates that the energy storage absorbs reactive power from the grid. Therefore, in order to uniformly measure the reactive power regulation burden currently borne by the grid-type energy storage unit, the absolute value of the current reactive power output value is taken to obtain the absolute value of the reactive power output of the grid-type energy storage unit. The magnitude of the absolute value of reactive power output reflects the reactive power regulation cost currently borne by the grid-type energy storage unit to maintain the voltage stability of the collection point, and is the core basis for subsequent iterative updates of the voltage command value of the renewable energy generation units.

[0029] In one feasible approach, before the step of real-time acquisition of the absolute value of reactive power output of the aforementioned grid-type energy storage unit, the method further includes: obtaining the target voltage command value of the convergence point; sending the target voltage command value to the grid-type energy storage unit; and using the target voltage command value as the current voltage command value during the first iteration of the new energy power generation unit.

[0030] Specifically, the convergence point is the point of common coupling. The target voltage command value for the convergence point can be issued by the Energy Management System (EMS). The target voltage command value refers to the voltage value that the convergence point should maintain, calculated by the EMS. Therefore, the target voltage command value is the core objective of regulation. The obtained target voltage command value for the convergence point can then be sent to the grid-type energy storage unit. After receiving the target voltage command, the grid-type energy storage unit will automatically adjust its reactive power output to maintain the convergence point voltage consistent with the target voltage command value. Furthermore, since the current voltage command value of the renewable energy generation unit is generated iteratively, each generation is based on the result of the previous iteration. This necessitates an initial value for the first calculation. Therefore, the target voltage command value can be used as the current voltage command value for the renewable energy generation unit in the first iteration, ensuring that the iteration starting point is consistent with the system's regulation objective.

[0031] Step S20: Iteratively update the voltage command value of each new energy power generation unit in the isolated grid based on the preset voltage boundary and the absolute value of reactive power output. The direction of each iteration update is the direction that reduces the absolute value of reactive power output of the grid-type energy storage unit.

[0032] Specifically, the preset voltage boundary refers to the pre-defined allowable voltage range for each new energy power generation unit, including an upper and lower voltage limit. The preset voltage boundary is used to control the voltage command of the new energy power generation unit to ensure it does not exceed the safe operating range of the equipment. Reducing the absolute value of reactive power output of the grid-connected energy storage unit is the optimization goal of each iteration. In each iteration, adjustments are made based on the current voltage command value, and the impact of this adjustment on the absolute value of reactive power output of the grid-connected energy storage unit is evaluated through power flow calculations. If the absolute value of reactive power output decreases after adjustment, the adjustment direction is correct, and adjustments continue in that direction; otherwise, adjustments are made in the opposite direction. The updated voltage command value generated in each iteration is limited to the preset allowable voltage range to ensure it does not exceed the safe operating range of the equipment. Through multiple iterations, the voltage command value of each new energy power generation unit is continuously optimized, while the absolute value of reactive power output of the grid-connected energy storage unit is gradually reduced until the iteration is complete.

[0033] In one feasible approach, after the step of iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on the preset voltage boundary and the absolute value of reactive power output, the method further includes: determining whether a target voltage update command for the collection point has been received from the energy management system; when a target voltage update command for the collection point is received, restarting the iterative update of the voltage command value of each new energy power generation unit in the isolated grid according to the target voltage update command for the collection point.

[0034] Specifically, after each iteration update, it is also possible to check whether the EMS has issued a new collection point target voltage command. This is because when there is a significant change in the islanded grid operation status, such as during heavy load switching, the EMS recalculates and issues an updated collection point target voltage value. When a collection point target voltage update command is received, the current iteration update process needs to be interrupted, the updated collection point target voltage value is used as the new control target, and the iteration update is restarted with the updated collection point target voltage value as the initial value.

[0035] Step S30: Send the updated voltage command value for each iteration to the new energy control unit corresponding to the new energy power generation unit to adjust the absolute value of reactive power output of the grid-type energy storage unit; Specifically, after each iteration and update to obtain the voltage command value, the obtained voltage command value of the new energy power generation unit is sent to the corresponding new energy control unit, such as the photovoltaic inverter and wind turbine converter, through the communication interface. Upon receiving the voltage command value, the new energy power generation unit adjusts its reactive power output to ensure that the actual voltage matches the voltage command value. The change in the reactive power output of the new energy power generation unit affects the reactive power output required by the grid-type energy storage unit to maintain the voltage at the collection point, thus causing the absolute value of the reactive power output of the grid-type energy storage unit to decrease. This embodiment uses the voltage command value instead of the reactive power command value, which eliminates the reactive power closed-loop feedback link and effectively reduces communication channel occupancy and data interaction overhead.

[0036] Step S40: When the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets the preset convergence condition, the iterative update is terminated.

[0037] Specifically, after each iteration, it is necessary to determine whether the iteration termination condition is met. This can be done by calculating the deviation between the current voltage value of the new energy power generation unit and the voltage value of the previous iteration, and determining whether each deviation meets a preset convergence condition. For example, it can be checked whether the sum of all deviations is less than a preset threshold. If it is less, the system is considered to have converged to a stable state, meaning that the voltage of each node has not changed significantly between adjacent iterations, and the iteration can be terminated. If the sum of voltage deviations is greater than the preset convergence threshold, the next iteration continues. Alternatively, a threshold can be set individually for each node, and the condition for terminating the iteration can be determined based on the comparison between each deviation and the corresponding threshold.

[0038] In one feasible approach, when the deviation between the current voltage value of each new energy control unit and the voltage value of the previous iteration meets a preset convergence condition, the step of terminating the iterative update includes: calculating the deviation between the current voltage value of each new energy control unit and the voltage value of the previous iteration; summing the deviation values ​​of all new energy control units to obtain the total voltage deviation; and determining that the preset convergence condition is met and terminating the iterative update when the total voltage deviation is less than or equal to a preset convergence threshold.

[0039] Specifically, this embodiment uses the voltage deviation between two consecutive samples from each renewable energy node as the criterion. The adjustment process terminates when the sum of the absolute values ​​of the voltage deviations of all renewable energy nodes is less than a preset threshold. The voltage deviation calculation formula is:

[0040] Where i is the new energy node number; The voltage value (current value) of the i-th renewable energy node sampled at the k-th time. For the i-th new energy node, the k-th... Voltage value of the first sample (previous value); For voltage deviation and threshold.

[0041] During this process, after receiving the voltage reference command, the grid-type energy storage system will automatically adjust its reactive power output, participate in the voltage support of the collection point, and work with other voltage regulating devices to achieve the voltage regulation target.

[0042] Finally, when the voltage at the collection point stabilizes within the target range and all control units are operating normally, this voltage coordination control process ends.

[0043] This embodiment collects the absolute value of reactive power output of the grid-type energy storage unit in real time; iteratively updates the voltage command value of each renewable energy generation unit in the isolated grid based on a preset voltage boundary and the absolute value of reactive power output, wherein the direction of each iteration update is to reduce the absolute value of reactive power output of the grid-type energy storage unit; the voltage command value updated in each iteration is sent to the renewable energy control unit corresponding to the renewable energy generation unit to adjust the absolute value of reactive power output of the grid-type energy storage unit; the iteration update terminates when the deviation between the current voltage value of each renewable energy control unit and the voltage value of the previous iteration meets a preset convergence condition. This embodiment reduces the absolute value of reactive power output of the grid-type energy storage unit by iteratively updating the voltage command value of each renewable energy generation unit in the isolated grid, thereby enabling the grid-type energy storage unit to have sufficient reactive power regulation margin under voltage disturbances and improving the stability of the isolated grid under voltage disturbances.

[0044] Combination Figure 2 Please refer to Figure 3 In the islanded multi-node voltage control method provided in Embodiment 2 of this application, step S20 above further includes steps S201 to S203: Step S201: Obtain the current absolute value of reactive power output of the grid-type energy storage unit based on the current voltage command value of the new energy power generation unit in the current iteration cycle.

[0045] Specifically, during the iteration process, the voltage of the new energy power generation unit i in the current iteration cycle (the kth iteration) can be set to the current voltage command value. Under this operating condition, the corresponding reactive power output value can be directly obtained from the grid-type energy storage unit. The absolute value of the reactive power output is taken to obtain the current absolute value of the reactive power output of the grid-type energy storage unit.

[0046] Step S202: Calculate the absolute value of the disturbance reactive power output of the grid-type energy storage unit based on the current voltage command value and the preset disturbance value.

[0047] Specifically, during iterative updates, it's also necessary to consider that the iteration direction should be the direction that reduces the absolute value of the reactive power output of the grid-type energy storage unit. To meet this requirement, the current voltage command value of the new energy generation unit i can be... A preset small disturbance value δ is superimposed to obtain the disturbed voltage command value. The preset value of the small disturbance δ must be selected to meet the requirement that it does not affect the stable operation of the system, but can accurately reflect the impact of voltage changes on the reactive power output of energy storage.

[0048] Subsequently, the voltage of the new energy power generation unit i is set to the perturbed voltage command value. Under the premise that the voltage of other new energy power generation units remains unchanged and the voltage at the collection point remains unchanged at the target voltage value, power flow calculations can be performed to obtain the reactive power output value of the grid-type energy storage unit under disturbance conditions. The absolute value of the reactive power output after disturbance is taken to obtain the absolute value of the disturbance reactive power output of the grid-type energy storage unit.

[0049] In one feasible approach, the step of calculating the absolute value of the disturbance reactive power output of a grid-type energy storage unit based on the current voltage command value and a preset disturbance value includes: superimposing the preset disturbance value onto the current voltage command value to obtain the disturbance voltage command value; performing power flow calculation based on the disturbance voltage command value to obtain the disturbance reactive power output value corresponding to the grid-type energy storage unit; and taking the absolute value of the disturbance reactive power output value to obtain the absolute value of the disturbance reactive power output.

[0050] Specifically, the current voltage command value of new energy power generation unit i By superimposing a preset small disturbance value δ, the disturbance voltage command value can be obtained. The voltage command value of the new energy power generation unit i is temporarily set to the disturbance voltage command value. The voltages of other new energy power generation units are kept at their current voltage command values ​​(i.e., the values ​​from the k-th iteration), and the PCC voltage is kept constant at the target voltage value. Under these boundary conditions, the power flow calculation module can be called to numerically solve the power flow of the isolated network. Power flow calculation is a fundamental numerical method in power system analysis used to determine the steady-state operation of the power grid. Given the network topology, impedance parameters of each branch, and power injection or voltage setpoints of each node, a set of nonlinear algebraic equations (i.e., power flow equations) is solved to obtain the voltage amplitude and phase angle of each node in the power grid, and then the power distribution of each branch and each power source is calculated. The power grid structure parameters required for power flow calculation in an isolated network, including collector line impedance, box-type transformer parameters, and load power, are pre-stored in the storage unit of the coordinating controller.

[0051] Power flow calculations can yield the voltage and power distribution of the entire isolated grid under the current disturbance voltage command value, from which the disturbance reactive power output value corresponding to the grid-type energy storage unit can be extracted. This value can be positive, indicating that the energy storage generates reactive power, or negative, indicating that the energy storage absorbs reactive power. It depends on the direction of reactive power regulation that the energy storage unit needs to undertake to maintain the stability of the collection point voltage under the current operating conditions. Therefore, the absolute value can be taken.

[0052] Step S203: Iteratively update the voltage command value of each new energy power generation unit in the isolated grid based on the current absolute value of reactive power output, the absolute value of disturbance reactive power output, and the preset voltage boundary.

[0053] Specifically, by comparing the absolute value of the current reactive power output with the absolute value of the disturbed reactive power output, it can be determined whether the voltage command value is more appropriate after increasing the disturbance value, thereby determining whether the current voltage command value needs to be increased. This process essentially determines the direction of change. Furthermore, it quantifies and assesses the specific impact of small changes in the voltage command value on the reactive power burden of energy storage, thus iteratively updating the next voltage command value.

[0054] In one feasible approach, the step of iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on the current absolute value of reactive power output, the absolute value of disturbance reactive power output, and a preset voltage boundary includes: determining the voltage adjustment direction based on the current absolute value of reactive power output and the absolute value of disturbance reactive power output; calculating candidate voltage command values ​​based on the voltage adjustment direction, the preset iteration step size, and the current voltage command value; and limiting the candidate voltage command values ​​within the preset voltage boundary to obtain the voltage command value updated in this iteration.

[0055] Specifically, this embodiment uses the steepest descent method to construct the SubPCC point voltage iteration formula. The core is to gradually update the voltage of each SubPCC point along the direction of decreasing absolute value of reactive power output in the grid-connected energy storage system. Simultaneously, limiting processing ensures that the SubPCC point voltage does not exceed a preset allowable range. Finally, each unit synchronously generates the next control command. The voltage command value iteration update formula is as follows:

[0056] in, To calculate the next voltage command value for the i-th new energy control point; To calculate the current voltage command value for the i-th new energy control point; The step size coefficient is used to adjust the voltage update amplitude and avoid iterative oscillation. Its value can be dynamically adjusted according to the actual operating conditions of the microgrid; δ is a preset small disturbance value. For the k-th iteration, the SubPCCi voltage is perturbed to The reactive power output value of the grid energy storage obtained by power flow calculation, assuming that the voltage of other SubPCC points remains unchanged and the voltage of PCC points is maintained at the target voltage command value; This is a limiting function, which limits x to a minimum value of y and a maximum value of z. In the formula, the limiting function is used to set the updated SubPCCi voltage within a preset allowable range. Inside, when the updated voltage value is less than When that happens, take it directly. When the updated voltage value is greater than When that happens, take it directly. When the updated voltage value is within the allowable range, the calculated updated voltage value is used. It represents the reactive power output value of the current grid-connected energy storage. Its positive and negative signs indicate the direction of reactive power flow (positive means that the energy storage generates reactive power, and negative means that the energy storage absorbs reactive power). The absolute value of reactive power output in grid-connected energy storage is the optimization objective of this invention.

[0057] This embodiment calculates the current absolute value of reactive power output of the grid-type energy storage unit based on the current voltage command value of the new energy power generation unit in the current iteration cycle; it calculates the absolute value of disturbed reactive power output of the grid-type energy storage unit based on the current voltage command value and a preset disturbance value; and iteratively updates the voltage command value of each new energy power generation unit in the isolated grid based on the current absolute value of reactive power output, the absolute value of disturbed reactive power output, and the preset voltage boundary. This embodiment determines the correct voltage adjustment direction by applying a small disturbance to the voltage of a single new energy power generation unit and observing the response change of the energy storage reactive power. Simultaneously, after each iteration, the voltage command value is limited within the preset boundary to ensure that the voltage of each node remains within a safe operating range during the iteration process, effectively avoiding local overvoltage or undervoltage.

[0058] For example, to facilitate understanding of the implementation flow of the islanded multi-node voltage control method of this application, please refer to... Figure 4 , Figure 4 A simplified flowchart of a method for controlling voltage at multiple nodes in an isolated grid is provided. Specifically: The first step is to receive voltage commands for renewable energy collection points from the Energy Management System (EMS); the second step is for the coordinating controller to generate reference voltage commands for renewable energy control points based on grid steady-state constraints and control strategies; the third step is to issue voltage reference values ​​for energy storage and each renewable energy control point; the fourth step is for the coordinating controller to collect electrical information and energy storage operation status at the control locations and evaluate the operation status of each control location in real time; the fifth step is to determine whether a new voltage command has been received from the EMS. If so, the process returns to the step of receiving voltage commands for renewable energy collection points from the EMS; if not, the process determines whether to stop debugging. If debugging is stopped, the process is complete; if not, the process returns to the step of the coordinating controller generating reference voltage commands for renewable energy control points based on grid steady-state constraints and control strategies.

[0059] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the control method of multi-node voltage in isolated grids in this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0060] This application also provides a control device for the voltage of multiple nodes in an isolated grid; please refer to [reference needed]. Figure 5 The control device for multi-node voltage in an isolated grid includes: The acquisition module 10 is used to acquire the absolute value of reactive power output of the grid-type energy storage unit in real time; The iteration module 20 is used to iteratively update the voltage command value of each new energy power generation unit in the isolated grid based on the preset voltage boundary and the absolute value of reactive power output. The direction of each iteration update is the direction that reduces the absolute value of reactive power output of the grid-type energy storage unit. The sending module 30 is used to send the voltage command value updated in each iteration to the new energy control unit corresponding to the new energy power generation unit, so as to adjust the absolute value of reactive power output of the grid-type energy storage unit. Termination module 40 is used to terminate the iterative update when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets the preset convergence condition.

[0061] This application collects the absolute value of reactive power output of the grid-type energy storage unit in real time; based on a preset voltage boundary and the aforementioned absolute value of reactive power output, iteratively updates the voltage command value of each new energy power generation unit in the islanded grid, wherein the direction of each iteration update is the direction that reduces the absolute value of reactive power output of the grid-type energy storage unit; the voltage command value updated in each iteration is sent to the new energy control unit corresponding to the new energy power generation unit to adjust the absolute value of reactive power output of the grid-type energy storage unit; when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets a preset convergence condition, the iterative update is terminated. This application reduces the absolute value of reactive power output of the grid-type energy storage unit by iteratively updating the voltage command value of each new energy power generation unit in the islanded grid, thereby enabling the grid-type energy storage unit to have sufficient reactive power regulation margin under voltage disturbances and improving the stability of the islanded grid under voltage disturbances.

[0062] In one embodiment, the iteration module 20 is further configured to obtain the current absolute value of reactive power output of the grid-type energy storage unit based on the current voltage command value of the new energy power generation unit in the current iteration cycle; calculate the absolute value of disturbance reactive power output of the grid-type energy storage unit based on the current voltage command value and the preset disturbance value; and iteratively update the voltage command value of each new energy power generation unit in the isolated grid based on the current absolute value of reactive power output, the absolute value of disturbance reactive power output, and the preset voltage boundary.

[0063] In one embodiment, the iteration module 20 is further configured to determine the voltage adjustment direction based on the absolute value of the current reactive power output and the absolute value of the disturbance reactive power output; calculate the candidate voltage command value based on the voltage adjustment direction, the preset iteration step size and the current voltage command value; limit the candidate voltage command value within the preset voltage boundary to obtain the voltage command value updated in this iteration.

[0064] In one embodiment, the iteration module 20 is further configured to superimpose the preset disturbance value onto the current voltage command value to obtain the disturbance voltage command value; perform power flow calculation based on the disturbance voltage command value to obtain the disturbance reactive power output value corresponding to the grid-type energy storage unit; and take the absolute value of the disturbance reactive power output value to obtain the disturbance reactive power output absolute value.

[0065] In one embodiment, the termination module 40 is further configured to calculate the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration; sum the deviation values ​​of all new energy power generation units to obtain the total voltage deviation; when the total voltage deviation is less than or equal to a preset convergence threshold, it is determined that the preset convergence condition is met, and the iterative update is terminated.

[0066] In one embodiment, the acquisition module 10 is further configured to acquire the target voltage command value of the convergence point; send the target voltage command value to the grid-type energy storage unit; and use the target voltage command value as the current voltage command value during the first iteration of the new energy power generation unit.

[0067] In one embodiment, the iteration module 20 is further configured to determine whether a target voltage update instruction for the collection point is received from the energy management system; when the target voltage update instruction for the collection point is received, the iteration update of the voltage instruction value of each new energy power generation unit in the isolated grid is restarted according to the target voltage update instruction for the collection point.

[0068] The islanded grid multi-node voltage control device provided in this application, employing the islanded grid multi-node voltage control method described in the above embodiments, can solve the technical problem of how to improve the stability of an islanded grid under voltage disturbances. Compared with the prior art, the beneficial effects of the islanded grid multi-node voltage control device provided in this application are the same as those of the islanded grid multi-node voltage control method provided in the above embodiments, and other technical features in the above-described islanded grid multi-node voltage control device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0069] This application provides a control device for the voltage of multiple nodes in an isolated grid. The control device includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the control method for the voltage of multiple nodes in the isolated grid described in Embodiment 1 above.

[0070] The following is for reference. Figure 6The diagram illustrates a structural schematic of a control device suitable for implementing the islanded multi-node voltage of the embodiments of this application. The control device for islanded multi-node voltage in the embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (Personal Digital Assistants), tablets, PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 6 The control device for multi-node voltage in an isolated grid shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0071] like Figure 6 As shown, the control device for islanded multi-node voltage can include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in ROM (Read Only Memory) 1002 or a program loaded from storage device 1003 into RAM (Random Access Memory) 1004. RAM 1004 also stores various programs and data required for the operation of the islanded multi-node voltage control device. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via bus 1005. Input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the control device for islanded multi-node voltage to communicate wirelessly or wiredly with other devices to exchange data. Although the figure shows control devices for islanded multi-node voltage with various systems, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems can be implemented alternatively.

[0072] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0073] The islanded network multi-node voltage control device provided in this application, employing the islanded network multi-node voltage control method described in the above embodiments, can solve the technical problem of how to improve the stability of an islanded network under voltage disturbances. Compared with the prior art, the beneficial effects of the islanded network multi-node voltage control device provided in this application are the same as those of the islanded network multi-node voltage control method provided in the above embodiments, and other technical features of the islanded network multi-node voltage control device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0074] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the above claims.

[0076] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the islanded multi-node voltage control method in the above embodiments.

[0077] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory) with one or more wires, optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0078] The aforementioned computer-readable storage medium may be included in the control device for islanded multi-node voltage; or it may exist independently and not be assembled into the control device for islanded multi-node voltage.

[0079] The aforementioned computer-readable storage medium carries one or more programs. When these programs are executed by the control device for the voltage of multiple nodes in an isolated grid, the control device performs the following actions: real-time acquisition of the absolute value of reactive power output of the grid-type energy storage unit; iterative updates of the voltage command value of each new energy power generation unit in the isolated grid based on a preset voltage boundary and the aforementioned absolute value of reactive power output, wherein the direction of each iteration update is the direction that reduces the absolute value of reactive power output of the grid-type energy storage unit; sends the voltage command value updated in each iteration to the new energy control unit corresponding to the new energy power generation unit to adjust the absolute value of reactive power output of the grid-type energy storage unit; and terminates the iterative update when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets a preset convergence condition.

[0080] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0081] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0082] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0083] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described islanded multi-node voltage control method, thereby solving the technical problem of how to improve the stability of an islanded network under voltage disturbances. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the islanded multi-node voltage control method provided in the above embodiments, and will not be repeated here.

[0084] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described method for controlling the voltage of multiple nodes in an isolated network.

[0085] The computer program product provided in this application can solve the technical problem of how to improve the stability of islanded networks under voltage disturbances. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the islanded network multi-node voltage control method provided in the above embodiments, and will not be repeated here.

[0086] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method for controlling the voltage of multiple nodes in an isolated network, characterized in that, The isolated grid includes grid-type energy storage units and multiple new energy power generation units, with each new energy power generation unit corresponding to a new energy control unit. The method includes: The absolute value of reactive power output of the grid-type energy storage unit is collected in real time; Based on a preset voltage boundary, the voltage command value of each new energy power generation unit in the isolated grid is iteratively updated according to the absolute value of the reactive power output. The direction of each iteration is the direction that reduces the absolute value of the reactive power output of the grid-type energy storage unit. The voltage command value updated in each iteration is sent to the new energy control unit corresponding to the new energy power generation unit to adjust the absolute value of the reactive power output of the grid-type energy storage unit. The iteration update terminates when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets the preset convergence condition.

2. The method as described in claim 1, characterized in that, The step of iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on the preset voltage boundary and the absolute value of the reactive power output includes: Based on the current voltage command value of the new energy power generation unit in the current iteration cycle, obtain the current absolute value of reactive power output of the grid-type energy storage unit; Based on the current voltage command value and the preset disturbance value, calculate the absolute value of the disturbance reactive power output of the grid-type energy storage unit; The voltage command value of each new energy power generation unit in the isolated grid is iteratively updated based on the current absolute value of reactive power output, the absolute value of disturbance reactive power output, and the preset voltage boundary.

3. The method as described in claim 2, characterized in that, The step of iteratively updating the voltage command value of each new energy power generation unit in the islanded grid based on the current absolute value of reactive power output, the absolute value of disturbed reactive power output, and the preset voltage boundary includes: The voltage adjustment direction is determined based on the current absolute value of reactive power output and the absolute value of disturbance reactive power output. Calculate candidate voltage command values ​​based on the voltage adjustment direction, the preset iteration step size, and the current voltage command value; The candidate voltage command value is limited within the preset voltage boundary to obtain the voltage command value updated in this iteration.

4. The method as described in claim 2, characterized in that, The step of calculating the absolute value of the disturbance reactive power output of the grid-type energy storage unit based on the current voltage command value and the preset disturbance value includes: The preset disturbance value is superimposed on the current voltage command value to obtain the disturbance voltage command value; Power flow calculation is performed based on the disturbance voltage command value to obtain the disturbance reactive power output value corresponding to the grid-type energy storage unit; The absolute value of the disturbance reactive power output is obtained by taking the absolute value of the disturbance reactive power output.

5. The method as described in claim 1, characterized in that, The step of terminating the iterative update when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets the preset convergence condition includes: Calculate the deviation between the current voltage value and the voltage value of the previous iteration for each new energy power generation unit; The total voltage deviation is obtained by summing the deviation values ​​of all new energy power generation units. When the sum of the voltage deviations is less than or equal to the preset convergence threshold, the preset convergence condition is satisfied, and the iterative update is terminated.

6. The method as described in claim 1, characterized in that, Before the step of real-time acquisition of the absolute value of reactive power output of the grid-type energy storage unit, the method further includes: Obtain the target voltage command value at the convergence point; The target voltage command value is sent to the grid-type energy storage unit, and the target voltage command value is used as the current voltage command value during the first iteration of the new energy power generation unit.

7. The method as described in claim 1, characterized in that, After the step of iteratively updating the voltage command value of each new energy power generation unit in the isolated grid based on the preset voltage boundary and the absolute value of the reactive power output, the method further includes: Determine whether a target voltage update command for the collection point has been received from the energy management system; When the target voltage update instruction for the collection point is received, the voltage instruction value of each new energy power generation unit in the isolated grid is updated iteratively again according to the target voltage update instruction for the collection point.

8. A control device for multi-node voltage in an isolated network, characterized in that, The device includes: The acquisition module is used to acquire the absolute value of reactive power output of the grid-type energy storage unit in real time; An iterative module is used to iteratively update the voltage command value of each new energy power generation unit in the isolated grid based on a preset voltage boundary and the absolute value of the reactive power output. The direction of each iteration update is the direction that reduces the absolute value of the reactive power output of the grid-type energy storage unit. The sending module is used to send the voltage command value updated in each iteration to the new energy control unit corresponding to the new energy power generation unit, so as to adjust the absolute value of the reactive power output of the grid-type energy storage unit. The termination module is used to terminate the iterative update when the deviation between the current voltage value of each new energy power generation unit and the voltage value of the previous iteration meets the preset convergence condition.

9. A control device for multi-node voltage in an isolated network, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the control method for islanded multi-node voltage as described in any one of claims 1 to 7.

10. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the control method for the voltage of multiple nodes in an isolated network as described in any one of claims 1 to 7.

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