A power exchange control method and device for flexible DC power transmission

Abstract

The present invention discloses a power exchange control method and device for flexible DC power transmission, belonging to the field of flexible DC power transmission. The method includes: obtaining the real-time operating condition parameters of each converter station in the flexible DC power transmission system; calculating the available power regulation capabilities of each converter station based on the real-time operating condition parameters to obtain the power regulation margins of each converter station; determining the power exchange control objectives of each converter station according to the power regulation margins of each converter station; allocating the determined power exchange control objectives to each converter station to generate power regulation commands for each converter station; driving each converter station to perform power regulation to complete the power exchange control between the converter stations in the flexible DC power transmission system. This application solves the technical problem of low power exchange control accuracy in the prior art for flexible DC power transmission systems and achieves the technical effect of improving the power exchange control accuracy of flexible DC power transmission systems.

Description

Technical Field

[0001] The present invention relates to the field of flexible DC power transmission, and particularly to a power exchange control method and device for flexible DC power transmission. Background Art

[0002] Flexible DC power transmission technology is widely used in modern power grids. However, current power exchange control is usually based on preset control strategies and parameters, lacking adaptability to the real-time operating conditions of the system and not fully considering the actual adjustment capabilities of each converter station. When performing power adjustment, the adjustment capabilities of some converter stations may be overused, while the adjustment potential of some other converter stations is not fully exploited. Therefore, when the operating conditions of the power grid change, the existing power exchange control is difficult to adapt to the real-time power grid state, resulting in low power exchange control accuracy. Summary of the Invention

[0003] This application provides a power exchange control method and device for flexible DC power transmission, aiming to solve the technical problem of low power exchange control accuracy in the existing flexible DC power transmission system.

[0004] In view of the above problems, this application provides a power exchange control method and device for flexible DC power transmission.

[0005] In the first aspect disclosed in this application, a power exchange control method for flexible DC power transmission is provided. The method includes: obtaining real-time operating condition parameters of each converter station in the flexible DC power transmission system, including DC voltage, DC current, active power, and reactive power; calculating the available power adjustment capabilities of each converter station based on the obtained real-time operating condition parameters to obtain the power adjustment margin of each converter station; determining the power exchange control objectives of each converter station according to the power adjustment margin of each converter station, including active power exchange objectives and reactive power exchange objectives; allocating the determined power exchange control objectives to each converter station to generate power adjustment instructions for each converter station; and sending the generated power adjustment instructions to the control systems of each converter station to drive each converter station to perform power adjustment according to the power adjustment instructions, thereby completing the power exchange control among the converter stations in the flexible DC power transmission system.

[0006] Another aspect disclosed in this application provides a power exchange control device for flexible DC transmission. The device includes: a working condition data acquisition module for acquiring real-time working condition parameters of each converter station in the flexible DC transmission system, including DC voltage, DC current, active power, and reactive power; a regulation margin acquisition module for calculating the available power regulation capabilities of each converter station based on the acquired real-time working condition parameters to obtain the power regulation margins of each converter station; a control target determination module for determining the power exchange control targets of each converter station according to the power regulation margins of each converter station, including active power exchange targets and reactive power exchange targets; a regulation instruction generation module for allocating the determined power exchange control targets to each converter station to generate power regulation instructions for each converter station; and a power exchange control module for sending the generated power regulation instructions to the control systems of each converter station to drive each converter station to perform power regulation according to the power regulation instructions and complete the power exchange control between each converter station in the flexible DC transmission system.

[0007] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0008] By adopting the technical solution of acquiring real-time working condition parameters of each converter station in the flexible DC transmission system, including DC voltage, DC current, active power, and reactive power, it provides a necessary data basis for calculating the power regulation margin and determining the power exchange control target; calculating the available power regulation capabilities of each converter station based on the acquired real-time working condition parameters to obtain the power regulation margins of each converter station, providing a basis for optimizing the power exchange control; determining the power exchange control targets of each converter station according to the power regulation margins of each converter station, including active power exchange targets and reactive power exchange targets, to achieve an optimized allocation of the system's power regulation capabilities; allocating the determined power exchange control targets to each converter station to generate power regulation instructions for each converter station, generating specific power regulation instructions for each converter station to implement the issuance and execution of the power exchange control; sending the generated power regulation instructions to the control systems of each converter station to drive each converter station to perform power regulation according to the power regulation instructions and complete the power exchange control between each converter station in the flexible DC transmission system. By sending power regulation instructions to drive each converter station to cooperate in power regulation and complete the power exchange control between converter stations, it improves the accuracy and efficiency of system control, solving the technical problem of low power exchange control accuracy in the existing flexible DC transmission system and achieving the technical effect of improving the power exchange control accuracy of the flexible DC transmission system.

[0009] The above description is only an overview of the technical solutions of this application. In order to be able to understand the technical means of this application more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features, and advantages of this application more obvious and understandable, the specific embodiments of this application are hereinafter specifically exemplified. Description of the Drawings

[0010] Figure 1 FIG. 1 is a schematic flow chart of a power exchange control method for flexible DC power transmission provided by an embodiment of the present application.

[0011] Figure 2 FIG. 2 is a schematic structural diagram of a power exchange control device for flexible DC power transmission provided by an embodiment of the present application.

[0012] Description of the reference numerals: The operating condition data acquisition module 11, the adjustment margin acquisition module 12, the control target determination module 13, the adjustment instruction generation module 14, and the power exchange control module 15. Detailed Embodiments

[0013] The general idea of the technical solution provided by the present application is as follows:

[0014] An embodiment of the present application provides a power exchange control method and device for flexible DC power transmission. By acquiring the real-time operating condition parameters of each converter station in the flexible DC power transmission system, calculating the power adjustment margin of each converter station, and determining the power exchange control target of each converter station accordingly, and then allocating the control target to each converter station, generating and issuing a power adjustment instruction, and driving each converter station to perform power adjustment collaboratively, so as to realize the power exchange control between the converter stations in the flexible DC power transmission system.

[0015] Specifically, first, by acquiring real-time operating condition parameters such as the DC voltage, DC current, active power, and reactive power of each converter station, a data basis is provided for subsequent calculations and controls. Secondly, based on the acquired real-time operating condition parameters, the available power adjustment capabilities of each converter station are calculated to obtain the power adjustment margin of each converter station, and the actual adjustment potential of each converter station is evaluated. Thirdly, according to the power adjustment margin of each converter station, the active and reactive power exchange control targets of each converter station are determined to optimize the power adjustment capacity configuration of the system. Then, the determined power exchange control target is allocated to each converter station to generate corresponding power adjustment instructions. Finally, by issuing the power adjustment instructions, each converter station is driven to perform power adjustment according to the instructions to collaboratively complete the power exchange control between the converter stations in the flexible DC power transmission system.

[0016] In summary, the present application uses real-time operating condition parameters, evaluates the adjustment margin of the converter station, optimizes the power exchange control target, and issues collaborative adjustment instructions, improving the power exchange control accuracy and efficiency of the flexible DC power transmission system.

[0017] After introducing the basic principle of the present application, the following will specifically introduce various non-limiting embodiments of the present application in conjunction with the accompanying drawings of the specification.

[0018] Embodiment 1

[0019] As Figure 1 shown, an embodiment of the present application provides a power exchange control method for flexible DC power transmission, and the method includes:

[0020] S1: Obtain the real-time operating condition parameters of each converter station in the flexible DC power transmission system, including DC voltage, DC current, active power, and reactive power.

[0021] Specifically, first, key operating parameters of each converter station in the flexible DC power transmission system are collected in real time as the basic information for power exchange control. Specifically, the real-time operating condition parameters include DC voltage, DC current, active power, and reactive power. Among them, the DC voltage and DC current reflect the operating state of the DC side of each converter station at the current moment; the active power represents the magnitude of the active power transmitted by each converter station to the AC power grid or absorbed from the AC power grid, and the reactive power reflects the reactive power support capacity provided by each converter station when participating in the voltage regulation of the AC power grid.

[0022] By collecting the DC voltage, DC current, active power, and reactive power of each converter station in real time, the real-time operating conditions of each converter station are comprehensively grasped, the current operating level and potential power regulation ability of each converter station are understood, and data support is provided for the subsequent optimization of the power exchange control target.

[0023] S2: Based on the obtained real-time operating condition parameters, calculate the available power regulation ability of each converter station to obtain the power regulation margin of each converter station.

[0024] Specifically, after obtaining the real-time operating condition parameters of each converter station, calculate the available power regulation ability of each converter station, that is, evaluate how much active and reactive power regulation capacity each converter station can still provide under the current operating state, and use it as the power regulation margin of each converter station, so as to master the real-time operating state and potential regulation ability of each converter station, and provide a basis for subsequent power exchange control. For example, by comparing the real-time operating condition parameters of each converter station with its own technical parameters, the power regulation margin of each converter station is evaluated, that is, on the premise of ensuring the safe and stable operation of each converter station, determine the degree of participation in active and reactive power regulation. The size of the power regulation margin determines the contribution degree of the converter station to the power exchange of the flexible DC power transmission system. Among them, the larger the power regulation margin, the greater the range in which the converter station can participate in regulation.

[0025] S3: According to the power regulation margin of each converter station, determine the power exchange control target of each converter station, including the active power exchange target and the reactive power exchange target.

[0026] Specifically, after determining the power regulation margin of each converter station, specific power exchange control objectives are determined for each converter station based on this margin information. The power exchange control objectives of the converter station include two aspects: the active power exchange objective and the reactive power exchange objective. Among them, the active power exchange objective reflects the quantity and direction of the active power exchange between the converter station and other converter stations through the flexible DC transmission system; the reactive power exchange objective reflects the magnitude of the reactive power support provided by the converter station when participating in the AC grid voltage regulation.

[0027] Since the power regulation margin characterizes the upper limit of the available regulation capacity of the converter station, when determining the power exchange control objectives of each converter station, the power exchange control objectives of each converter station must be restricted within the range allowed by the corresponding power regulation margin, so as to ensure the feasibility of the generated objectives and avoid invalid control instructions that exceed the capacity limit of the converter station. At the same time, the formulation of the power exchange control objectives needs to meet the power demand data of each AC grid, which is used as an optimization constraint condition in the power exchange control decision-making process, so as to search for the power exchange control objectives that can maximize the utilization of the regulation capacity of each converter station.

[0028] S4: Assign the determined power exchange control objectives to each converter station to generate power regulation instructions for each converter station.

[0029] Specifically, after determining the power exchange control objectives of each converter station, these control objectives are converted into specific power regulation instructions and sent to the corresponding converter station. The power regulation instructions of the converter station include two parts: the active power regulation instruction and the reactive power regulation instruction, which respectively correspond to the generated active power exchange objective and reactive power exchange objective.

[0030] The power exchange control objective is given in the form of a total target. During the control process, according to the control characteristics and requirements of each converter station, the total target needs to be further decomposed into a series of discrete power regulation instruction values, such as the active power increment that the converter station should adjust within each control period. Among them, different converter stations have differences in technical parameters and control methods, so targeted processing is required when generating power regulation instructions to ensure that the power regulation instructions can meet the actual control needs of each converter station.

[0031] S5: Send the generated power regulation instructions to the control systems of each converter station to drive each converter station to perform power regulation according to the power regulation instructions, and complete the power exchange control between the converter stations in the flexible DC transmission system.

[0032] Specifically, after generating the power regulation instructions for each converter station, these instructions are sent to the control systems of each converter station to trigger each converter station to perform corresponding power regulation actions, thereby realizing the power exchange control between the converter stations in the flexible DC transmission system.

[0033] When the control systems of each converter station receive the power regulation command, first, the power regulation command is parsed and verified to identify the specific control actions and relevant parameters required by the power regulation command. After confirming that the command is legal and valid, the control system starts the corresponding control according to the content of the power regulation command, adjusts the active power and reactive power output of the converter station, and realizes the power regulation amount required by the command. During the power regulation process, the control systems of each converter station monitor the operating status and electrical parameters of the converter station in real time, and conduct safety supervision and protection on the regulation process. Once it is found that the regulation process is abnormal or exceeds the safe operating range, the control system promptly takes restrictive measures or triggers protection actions to ensure that the safe and stable operation of the converter station equipment and the power grid system is not affected. When all converter stations have completed the corresponding power regulation actions according to the power regulation command, it means that the power exchange control strategy is realized in the flexible DC transmission system, and the power exchange control accuracy of the flexible DC transmission system is improved.

[0034] Furthermore, the embodiments of the present application further include:

[0035] The DC voltage and DC current of each converter station are respectively collected in real time by using the voltage sensors and current sensors arranged in each converter station; the DC voltage and DC current of each converter station are respectively transmitted to the corresponding measurement unit, and the measurement unit obtains the active power and reactive power of each converter station according to the DC voltage and DC current.

[0036] In a feasible implementation manner, in order to obtain the real-time operating condition parameters of each converter station, first, voltage sensors and current sensors are installed on the DC side of each converter station. Among them, the voltage sensor is used to measure the voltage value at both ends of the DC bus of the converter station in real time, reflecting the voltage level on the DC side of the converter station; the current sensor is used to measure the DC output current of each converter in the converter station in real time, reflecting the operating status and power output level of each converter. Through the voltage sensors and current sensors of each converter station, voltage and current data are respectively collected in real time to obtain the DC voltage and DC current of each converter station.

[0037] Subsequently, the DC voltage and DC current of each converter station are transmitted to the corresponding measurement unit. The measurement unit is composed of a microprocessor, a memory, a communication interface, etc., and is a dedicated computing device. The parameter information of each converter station, such as converter type, transformer turns ratio, control coefficient, etc., is pre-stored inside the measurement unit. When receiving the DC voltage and DC current, the measurement unit selects a suitable calculation model according to these parameters, such as an ideal converter model, an equivalent circuit model, etc., substitutes the DC voltage, DC current and parameters into the model formula, and after calculation, obtains the active power and reactive power of each converter station.

[0038] Further, the embodiments of the present application further include:

[0039] After receiving the DC voltage and DC current, the measurement unit selects the corresponding calculation formula according to the pre-configured converter station parameter information, and calculates the instantaneous active power and instantaneous reactive power of the converter station respectively; performs filtering processing on the calculated instantaneous active power and instantaneous reactive power, and performs a moving average within a time window on the filtered instantaneous active power and instantaneous reactive power to obtain the average active power and average reactive power of each converter station, which are used as the active power and reactive power of each converter station.

[0040] In a preferred embodiment, after each measurement unit receives the DC voltage and DC current of the corresponding converter station, the measurement unit first reads the parameter information corresponding to the converter station from the internal memory, such as converter topology structure parameters, transformer winding turns ratio, control coefficients, etc. According to these parameters, the measurement unit selects a mathematical model and a calculation formula, such as an ideal converter model, an equivalent circuit model, etc. These models describe the electrical characteristics of the converter station through a series of equations. The measurement unit substitutes the DC voltage and DC current into the selected calculation formula, combines the converter station parameters, and performs corresponding arithmetic operations according to the model definition to solve the instantaneous active power value and instantaneous reactive power value of the converter station.

[0041] Since there are certain pulsations and noises in the DC voltage and DC current, if the instantaneous active power and instantaneous reactive power are directly used, it will cause data jitter and affect the accuracy of power calculation. Therefore, filtering processing is required to remove the interference of high-frequency noise and harmonics. Among them, filtering can be realized by means of a low-pass filter, Kalman filtering, etc. There may still be certain short-term fluctuations in the filtered active power and reactive power data. In order to obtain a relatively smooth and stable power calculation result, the measurement unit performs a moving average processing on the data within a certain time window. That is, the power values of multiple sampling periods are accumulated within the time window, and the average value is calculated as the active power and reactive power output of this time period. This average value is more reliable, can better reflect the actual output power level of the converter station, reduces the power calculation deviation caused by measurement errors and short-term disturbances, and thus lays a data foundation for subsequent power regulation and control.

[0042] Further, the embodiments of the present application further include:

[0043] Read the rated capacity parameters of the converter station from the parameter database of each converter station; compare the real-time operating condition parameters of the converter station with the rated capacity parameters to obtain the current operating load level of each converter station; according to the pre-set safe operating threshold, combined with the current operating load level of each converter station, obtain the maximum available power regulation capacity of the converter station in the current state, and use it as the power regulation margin of each converter station.

[0044] In a feasible implementation manner, in a flexible DC power transmission system, during the design and commissioning phases of each converter station, all its technical index parameters are determined and stored in a parameter database for calling during operation management. Among them, the rated capacity parameters of the converter station reflect the maximum active power and reactive power that the converter station can stably output under normal working conditions, and determine the upper limit of the power transmission and voltage regulation capabilities of the converter station. Among them, the parameter database is located locally at the converter station and can be accessed in-situ through a data communication network. When calculating the power regulation capabilities of each converter station, the rated capacity parameters of the corresponding converter station are read from the parameter database as the benchmark for power regulation margin evaluation.

[0045] Subsequently, the real-time operating condition parameters of the converter station are compared with the corresponding rated capacity parameters, and the percentages of the current active power and reactive power outputs of the converter station in the rated capacity are calculated, that is, the active load rate and the reactive load rate, to obtain the current operating load levels of each converter station. These two load rate indicators reflect the actual usage degrees of the active power and reactive power of the converter station in the current state. The higher the load rate, the smaller the remaining regulation space of the converter station.

[0046] Due to the safe operation requirements of the converter station equipment, when performing power regulation, it is necessary to control the outputs of the active power and reactive power within a certain safe range to avoid exceeding the rated capacity and causing equipment damage. Therefore, a safe operation threshold is preset as the upper limit constraint for power regulation. Specifically, for each converter station, the current operating load level of the converter station is compared with the safe operation threshold to obtain the amounts of active power and reactive power that the converter station can still regulate on the premise of ensuring safe operation, that is, the maximum available regulation capacity, and this regulation capacity value is the power regulation margin of the converter station. Among them, the larger the power regulation margin, the more capable the converter station is of participating in the power exchange control of the flexible DC power transmission system without affecting safety. The subsequent optimization of control objectives and generation of commands both need to be carried out within the range allowed by the power regulation margin to ensure the executability of the control commands and the safe and reliable operation of the system.

[0047] Furthermore, the embodiments of the present application further include:

[0048] Real-time obtain the power demand data of each AC power grid as the optimization control constraint; use the power regulation margins of each converter station as the optimization control variables, and take maximizing the utilization of the power regulation margins of each converter station as the optimization control objective to perform control optimization, and obtain the power exchange control objectives of each converter station that meet the optimization control constraint, including the active power exchange objective and the reactive power exchange objective.

[0049] Specifically, during the operation of the flexible DC transmission system, the power demand of each connected AC grid is monitored in real time. Due to reasons such as load fluctuations and peak shaving of generator sets, the demand for active power and reactive power of each AC grid will change at any time. Therefore, when formulating the power exchange control objective of the converter station, it is necessary to obtain the latest power demand data of each AC grid in real time as the constraint condition for control decision-making. Only when the power exchange control objective can meet the power demand of the relevant AC grid can the normal power supply and voltage quality of the grid be ensured, and abnormal situations such as power gaps or voltage over-limit can be avoided.

[0050] Meanwhile, the power regulation margin of each converter station is used as the optimization control variable. The larger the power regulation margin of the converter station, the larger the adjustable range for its participation in power exchange control. Therefore, during the optimization control, by adjusting the active power regulation objective and reactive power regulation objective of each converter station, the power regulation margin of each converter station is utilized to the maximum extent. Taking maximizing the utilization of the power regulation margin of each converter station as the control objective, through optimization algorithms such as genetic algorithms and particle swarm algorithms, the power exchange control objective of each converter station is solved on the premise of meeting the power demand constraints of each AC grid. The optimization algorithm adjusts the values of the active power exchange objective and reactive power exchange objective of each converter station through an iterative optimization process, evaluates the fitness corresponding to each combination of objective values, and finally outputs the solution that meets the constraint conditions and has the best fitness as the final power exchange control objective of each converter station. This objective includes two parts: the active power exchange objective and the reactive power exchange objective, which respectively guide the specific values of the active power transmitted or absorbed by each converter station to the connected AC grid and the reactive power support provided. Through the optimization solution process, the efficient allocation of resources in the flexible DC transmission system can be realized, and the power regulation potential of each converter station can be maximally exerted on the premise of meeting the demands of each grid.

[0051] Furthermore, the embodiments of the present application further include:

[0052] Based on the power regulation margin of each converter station and the optimization control constraints, construct the power regulation space of each converter station, where each power regulation space includes an active power regulation space and a reactive power regulation space; randomly select values in the active power regulation space and the reactive power regulation space of each converter station respectively to obtain the first active power exchange control target and the first reactive power exchange control target; construct a fitness evaluation function, substitute the first active power exchange control target and the first reactive power exchange control target into the fitness evaluation function to obtain the first fitness; randomly select values in the active power regulation space and the reactive power regulation space of each converter station again to obtain the second active power exchange control target and the second reactive power exchange control target; substitute the second active power exchange control target and the second reactive power exchange control target into the fitness evaluation function to obtain the second fitness; compare the first fitness with the second fitness to obtain the preferred active power exchange control target and the preferred reactive power exchange control target; iterate, and when the preset convergence condition is reached, obtain the power exchange control target of each converter station.

[0053] In a feasible implementation manner, first, obtain the power regulation margin of each converter station, including the active power regulation margin and the reactive power regulation margin. The power regulation margin defines the maximum range within which the active power and reactive power of the converter station can be adjusted while ensuring safe operation. At the same time, clarify the constraint conditions required for optimization control, that is, the real-time demand data of active power and reactive power of each connected AC power grid, which sets the upper limit of the power regulation of the converter station. Then, based on the power regulation margin of each converter station and the optimization control constraints, construct a power regulation space for the converter station, which consists of an active power regulation space and a reactive power regulation space. Among them, the upper limit of the active power regulation space is the maximum active power increment of the converter station, and the lower limit is the maximum active power decrement. These two limit values are jointly determined by the power regulation margin and the optimization control constraints; the upper and lower limits of the reactive power regulation space are the maximum reactive power increment and the maximum reactive power decrement respectively. By constructing the power regulation space, clarify the entire range within which the active power and reactive power of each converter station can be adjusted under the premise of meeting the constraint conditions, providing a space basis for subsequent optimization search.

[0054] Then, within the power regulation space of each constructed converter station, random sampling is respectively carried out on the active power regulation space and the reactive power regulation space to obtain a set of initial active power exchange control target values and reactive power exchange control target values, which serve as the first active power exchange control target and the first reactive power exchange control target. To evaluate the quality of the obtained first active power exchange control target and first reactive power exchange control target, a fitness evaluation function is constructed. Substituting the obtained first set of active power exchange control target and reactive power exchange control target into the fitness evaluation function, a fitness value can be calculated as the first fitness, reflecting the qualified degree of the first active power exchange control target and the first reactive power exchange control target in meeting the optimization objectives and constraint conditions, laying a foundation for subsequent iterative optimization.

[0055] After that, random sampling is carried out again within the power regulation space of each converter station to obtain another set of active power exchange control target values and reactive power exchange control target values, resulting in the second active power exchange control target and the second reactive power exchange control target, which serve as new candidate solutions. By continuously randomly taking values within the power regulation space, the search range is effectively expanded, increasing the probability of finding the global optimal solution. Each random sampling may generate a better combination of control targets. Then, substitute the second active power exchange control target and the second reactive power exchange control target into the constructed fitness evaluation function to calculate the corresponding second fitness value. Next, compare the obtained first fitness and the second fitness. The group with the larger fitness value is regarded as the preferred solution in the current iteration. If the second fitness is greater than the first fitness, then use the second active power exchange control target and the second reactive power exchange control target as the preferred active power exchange control target and preferred reactive power exchange control target in the current iteration; otherwise, the first active power exchange control target and the first reactive power exchange control target are retained as the preferred active power exchange control target and preferred reactive power exchange control target in the current iteration.

[0056] Iteratively execute the optimization process of the control objective. Each iteration generates a new candidate solution, which is compared with the current optimal solution, gradually approaching the global optimal point. The termination conditions of the iteration are usually preset in advance, such as reaching the maximum number of iterations, the fitness value growth being less than the threshold for several consecutive generations, etc. When the iteration process meets the convergence conditions, the active power exchange control objective and the reactive power exchange control objective with the maximum fitness value during the iteration process are the finally determined power exchange control objectives for each converter station, including the active power exchange objective and the reactive power exchange objective for each converter station. This set of control objectives maximally utilizes the power regulation margin of each converter station on the premise of meeting the real-time power demand of each AC power grid. Through the iterative optimization process, the power exchange control objectives for each converter station are determined efficiently and accurately, improving the power regulation performance of the flexible DC transmission system.

[0057] Furthermore, the embodiments of the present application further include:

[0058] Construct the fitness evaluation function as:

[0059] ;

[0060] Wherein, is the fitness value, represents the total number of converter stations in the flexible DC transmission system; for the i-th converter station, is the active power exchange control objective of the current iteration in the optimization process of the i-th converter station, is the maximum active power exchange control objective of the i-th converter station, is the reactive power exchange control objective of the current iteration in the optimization process of the i-th converter station, is the maximum reactive power exchange control objective of the i-th converter station. By dividing and by the corresponding maximum values and respectively, the control objective values of different converter stations can be normalized in dimension, enabling them to be accumulated and summed on the same order of magnitude.

[0061] The value range of the fitness evaluation function is [0, 2N]. Wherein, The larger it is, the higher the utilization rate of the power regulation margin of each converter station by the control objective combination generated by the optimization, and the more in line with the optimization objective of maximizing the utilization of the power regulation margin of each converter station. When F takes the maximum value of 2N, it means that the and of all converter stations have reached the corresponding and , that is, the power adjustment margin of all converter stations is utilized 100%, which is the optimal case. And an F value of 0 indicates that the power adjustment margin of any converter station is not utilized. Therefore, in the iterative optimization process, the goal is to make the fitness constantly increase, gradually approach 2N, and finally find the control target combination with the maximum fitness as the power exchange control target finally determined for each converter station, so as to maximize the utilization of the power adjustment margin of each converter station.

[0062] In summary, a power exchange control method for flexible DC transmission provided by an embodiment of the present application has the following technical effects:

[0063] Obtain the real-time operating condition parameters of each converter station in the flexible DC transmission system, including DC voltage, DC current, active power, and reactive power, providing a necessary data basis for subsequent power adjustment margin calculation and power exchange control target determination. Based on the obtained real-time operating condition parameters, calculate the available power adjustment capabilities of each converter station to obtain the power adjustment margins of each converter station, master the available adjustment capabilities of each converter station, provide a basis for optimizing power exchange control, and avoid situations where adjustment instructions exceed the actual adjustment capabilities of the converter stations. According to the power adjustment margins of each converter station, determine the power exchange control targets of each converter station, including active power exchange targets and reactive power exchange targets, while ensuring the feasibility of adjustment, optimize the power adjustment capacity configuration of the system, and achieve the overall optimization of power exchange control. Allocate the determined power exchange control targets to each converter station to generate power adjustment instructions for each converter station, implement the control decision to each execution entity, and provide direct operation instructions for the implementation of power exchange control. Send the generated power adjustment instructions to the control systems of each converter station to drive each converter station to perform power adjustment according to the power adjustment instructions, complete the power exchange control between each converter station in the flexible DC transmission system, achieve the coordinated cooperation between each converter station, complete the actual power exchange control, and improve the accuracy and efficiency of power exchange control.

[0064] Embodiment 2

[0065] Based on the same inventive concept as a power exchange control method for flexible DC transmission in the foregoing embodiment, as Figure 2 shown, an embodiment of the present application provides a power exchange control device for flexible DC transmission, and the device includes:

[0066] An operating condition data acquisition module 11, configured to acquire real-time operating condition parameters of each converter station in the flexible DC transmission system, including DC voltage, DC current, active power, and reactive power;

[0067] An adjustment margin acquisition module 12, configured to calculate the available power adjustment capabilities of each converter station based on the acquired real-time operating condition parameters to obtain the power adjustment margins of each converter station;

[0068] A control target determination module 13, configured to determine power exchange control targets for each converter station according to the power regulation margins of each converter station, including active power exchange targets and reactive power exchange targets;

[0069] An adjustment instruction generation module 14, configured to allocate the determined power exchange control targets to each converter station, and generate power adjustment instructions for each converter station;

[0070] A power exchange control module 15, configured to send the generated power adjustment instructions to the control systems of each converter station, and drive each converter station to perform power regulation according to the power adjustment instructions, so as to complete the power exchange control between each converter station in the flexible DC power transmission system.

[0071] Further, the operating condition data acquisition module 11 includes the following execution steps:

[0072] Use the voltage sensors and current sensors set at each converter station to respectively and real-time collect the DC voltage and DC current of each converter station;

[0073] Transmit the DC voltage and DC current of each converter station to the corresponding measurement unit respectively, and the measurement unit obtains the active power and reactive power of each converter station according to the DC voltage and DC current.

[0074] Further, the operating condition data acquisition module 11 further includes the following execution steps:

[0075] After receiving the DC voltage and DC current, the measurement unit selects the corresponding calculation formula according to the pre-configured converter station parameter information, and calculates the instantaneous active power and instantaneous reactive power of the converter station respectively;

[0076] Perform filtering processing on the calculated instantaneous active power and instantaneous reactive power, and perform moving average within a time window on the filtered instantaneous active power and instantaneous reactive power, so as to obtain the average active power and average reactive power of each converter station, and use them as the active power and reactive power of each converter station.

[0077] Further, the regulation margin acquisition module 12 includes the following execution steps:

[0078] Read the rated capacity parameters of the converter station from the parameter database of each converter station;

[0079] Compare the real-time operating condition parameters of the converter station with the rated capacity parameters to obtain the current operating load level of each converter station;

[0080] According to the preset safe operation threshold and in combination with the current operation load levels of each converter station, the maximum available power regulation capacity of the converter station in the current state is obtained, and it is used as the power regulation margin of each converter station.

[0081] Further, the control target determination module 13 includes the following execution steps:

[0082] Obtain the power demand data of each AC power grid in real time as the optimization control constraint;

[0083] Taking the power regulation margin of each converter station as the optimization control variable and maximizing the utilization of the power regulation margin of each converter station as the optimization control target, perform control optimization to obtain the power exchange control targets of each converter station that meet the optimization control constraint, including the active power exchange target and the reactive power exchange target.

[0084] Further, the control target determination module 13 further includes the following execution steps:

[0085] Based on the power regulation margin of each converter station and the optimization control constraint, construct the power regulation space of each converter station, where each power regulation space includes an active power regulation space and a reactive power regulation space;

[0086] Randomly take values in the active power regulation space and the reactive power regulation space of each converter station respectively to obtain the first active power exchange control target and the first reactive power exchange control target;

[0087] Construct a fitness evaluation function, substitute the first active power exchange control target and the first reactive power exchange control target into the fitness evaluation function to obtain the first fitness;

[0088] Randomly take values again in the active power regulation space and the reactive power regulation space of each converter station respectively to obtain the second active power exchange control target and the second reactive power exchange control target;

[0089] Substitute the second active power exchange control target and the second reactive power exchange control target into the fitness evaluation function to obtain the second fitness;

[0090] Compare the first fitness with the second fitness to obtain the preferred active power exchange control target and the preferred reactive power exchange control target;

[0091] Iteratively execute, and when the preset convergence condition is reached, obtain the power exchange control targets of each converter station.

[0092] Further, the control target determination module 13 further includes the following execution steps:

[0093] The constructed fitness evaluation function is:

[0094] ;

[0095] Among them, is the fitness value, is the total number of converter stations, is the active power exchange control target in the optimization process of the i-th converter station, is the maximum active power exchange control target of the i-th converter station, is the reactive power exchange control target in the optimization process of the i-th converter station, is the maximum reactive power exchange control target of the i-th converter station.

[0096] Any step of the method described above can be stored as computer instructions or programs in an unrestricted computer memory and can be called and recognized by an unrestricted computer processor to implement any one of the methods in the embodiments of the present application, and no redundant restrictions are made here.

[0097] Furthermore, the first or second described above may not only represent an order relationship, but may also represent a specific concept, and / or refer to the selection of multiple elements individually or in whole. Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the present application and its equivalent technologies, the present application is intended to include these changes and modifications.

Claims

1. A power exchange control method for flexible direct current transmission, characterized in that: The method comprises: Obtain the real-time operating parameters of each converter station in the flexible DC transmission system, including DC voltage, DC current, active power and reactive power; Based on the acquired real-time operating parameters, the available power regulation capability of each converter station is calculated to obtain the power regulation margin of each converter station; According to the power regulation margin of each converter station, the power exchange control target of each converter station is determined, including the active power exchange target and the reactive power exchange target; Allocating the determined power exchange control target to each converter station, and generating a power adjustment instruction for each converter station; The generated power adjustment instruction is sent to the control system of each converter station, driving each converter station to adjust the power according to the power adjustment instruction, and completing the power exchange control between the converter stations in the flexible DC transmission system; According to the power regulation margin of each converter station, the power exchange control target of each converter station is determined, including: Obtain the power demand data of each AC power grid in real time as an optimization control constraint; Taking the power regulation margin of each converter station as the optimization control variable and maximizing the use of the power regulation margin of each converter station as the optimization control target, control optimization is performed to obtain the power exchange control target of each converter station that meets the optimization control constraints, including the active power exchange target and the reactive power exchange target; Taking the power regulation margin of each converter station as the optimization control variable and maximizing the use of the power regulation margin of each converter station as the optimization control target, control optimization is performed to obtain the power exchange control target of each converter station that meets the optimization control constraint, including: Based on the power regulation margin of each converter station and the optimization control constraint, construct a power regulation space of each converter station, wherein each power regulation space includes an active power regulation space and a reactive power regulation space; Randomly taking values ​​in the active power regulation space and the reactive power regulation space of each converter station to obtain a first active power exchange control target and a first reactive power exchange control target; Constructing a fitness evaluation function, substituting the first active power exchange control target and the first reactive power exchange control target into the fitness evaluation function to obtain a first fitness; Randomly taking values ​​in the active power regulation space and reactive power regulation space of each converter station again to obtain a second active power exchange control target and a second reactive power exchange control target; Substituting the second active power exchange control target and the second reactive power exchange control target into a fitness evaluation function to obtain a second fitness; Comparing the first fitness with the second fitness to obtain a preferred active power exchange control target and a preferred reactive power exchange control target; Iterative execution, when the preset convergence condition is reached, the power exchange control target of each converter station is obtained; The fitness evaluation function is constructed as: ； in, is the fitness value, is the total number of converter stations, is the active power exchange control target in the optimization process of the i-th converter station, is the maximum active power exchange control target of the i-th converter station, is the reactive power exchange control target in the optimization process of the i-th converter station, is the maximum reactive power exchange control target of the i-th converter station.

2. The power exchange control method of flexible direct current transmission according to claim 1, characterized in that: Obtain the real-time operating parameters of each converter station in the flexible DC transmission system, including: The voltage sensor and current sensor installed at each converter station are used to respectively collect the DC voltage and DC current of each converter station in real time; The DC voltage and DC current of each converter station are transmitted to the corresponding measurement unit respectively, and the active power and reactive power of each converter station are obtained through the measurement unit according to the DC voltage and DC current.

3. The power exchange control method of flexible direct current transmission according to claim 2, characterized in that: The active power and reactive power of each converter station are obtained through the measurement unit according to the DC voltage and DC current, including: After receiving the DC voltage and DC current, the measuring unit selects a corresponding calculation formula according to the pre-configured converter station parameter information to calculate the instantaneous active power and instantaneous reactive power of the converter station respectively; The calculated instantaneous active power and instantaneous reactive power are filtered, and the instantaneous active power and instantaneous reactive power after filtering are slidingly averaged within the time window to obtain the average active power and average reactive power of each converter station as the active power and reactive power of each converter station.

4. The power exchange control method of flexible direct current transmission according to claim 1, characterized in that: Based on the acquired real-time operating parameters, the available power regulation capability of each converter station is calculated to obtain the power regulation margin of each converter station, including: Reading the rated capacity parameters of the converter stations from the parameter database of each converter station; Compare the real-time operating parameters of the converter station with the rated capacity parameters to obtain the current operating load level of each converter station; According to the preset safe operation threshold value and the current operating load level of each converter station, the maximum available power regulation capacity of the converter station in the current state is obtained and used as the power regulation margin of each converter station.

5. A power exchange control device for flexible direct current transmission, characterized in that: A power exchange control method for implementing the flexible direct current transmission according to any one of claims 1 to 4, the device comprising: A working condition data acquisition module, which is used to obtain real-time working condition parameters of each converter station in the flexible DC power transmission system, including DC voltage, DC current, active power and reactive power; A regulation margin acquisition module, which is used to calculate the available power regulation capability of each converter station based on the acquired real-time operating condition parameters, and obtain the power regulation margin of each converter station; A control target determination module, the control target determination module is used to determine the power exchange control target of each converter station according to the power regulation margin of each converter station, including an active power exchange target and a reactive power exchange target; An adjustment instruction generation module, the adjustment instruction generation module is used to distribute the determined power exchange control target to each converter station and generate a power adjustment instruction for each converter station; A power exchange control module, which is used to send the generated power adjustment instructions to the control system of each converter station, drive each converter station to adjust power according to the power adjustment instructions, and complete the power exchange control between the converter stations in the flexible direct current transmission system.

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