Wide-area distributed phase modifier cluster cooperative control system and method

Abstract

The application discloses a wide-area distributed phase modifier cluster cooperative control system and method, relates to the technical field of power grid phase modifier control, and comprises a cooperative control master station arranged at a power grid dispatching end, phase modifier local control sub-stations distributed in various power plants and a wide-area measurement system for providing real-time data; the method comprises the following steps: the master station receives wide-area real-time data, generates a cooperative control instruction after judging a power grid stable state, and issues the cooperative control instruction to the sub-stations to execute reactive power regulation or seamless switching operation between power generation and phase modulation modes. The application can quickly respond to power grid disturbance, cooperatively suppress low-frequency oscillation, stabilize voltage, improve phase modifier operation reliability and provide stable support for a new type of power system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of grid phase modifier control, in particular to a wide-area distributed phase modifier cluster cooperative control system and method. BACKGROUND

[0002] With the continuous increase of new energy generation proportion, the structure and operation characteristics of the power system have undergone profound changes. The large-scale grid connection of renewable energy sources such as wind power and photovoltaic power has intensified the randomness and volatility of power output, which has exacerbated the frequent fluctuations of grid voltage and reduced the rotational inertia and damping of the system, making stability problems such as low-frequency oscillation increasingly prominent. In this context, tapping the phase modulation potential of traditional thermal power units and flexibly transforming them into phase modifier operation as reactive power compensation and stability support resources for the grid has become one of the important technical paths for building a new type of power system.

[0003] Currently, there have been many researches and practices on the related control technology of phase modifier. For example, some invention patents focus on solving the dynamic stability and control problem in the switching process from power generation mode to phase modulation mode of a single unit, and realize the smooth transition of single machine mode by optimizing the cooperation of excitation and prime mover. Some invention patents realize the automatic adjustment of the reactive power output of discrete capacitor banks, reactors and single generators by dispatching the main station to issue reactive power instructions to each plant and station, so as to maintain the stability of node voltage. However, the existing technology focuses on the localized control of single equipment or optimization based on slow SCADA data, and it is difficult to cope with the instantaneous disturbance of the grid.

[0004] In particular, when a large number of widely distributed phase modifiers are accessed to the grid as cluster resources, the existing technical system exposes obvious deficiencies: there is a lack of a mechanism that can quickly and cooperatively control the distributed phase modifier cluster based on wide-area real-time measurement information. The existing AVC system has a long instruction period and cannot meet the millisecond-level response requirement needed to suppress grid oscillation; and the single-machine control strategy is independent of each other and cannot coordinate the control of multiple phase modifiers to form a control force in a wide area, and even may cause new stability problems due to uncoordinated control actions. Therefore, how to realize the cooperative control of the wide-area distributed phase modifier cluster so that it can quickly respond to grid disturbances and provide strong dynamic reactive power support is a problem to be solved.

[0005] In summary, the existing technology has limitations in the rapidity, coordination and systematicness of control when dealing with the cluster cooperative control problem composed of multiple distributed phase modifiers. SUMMARY

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a wide-area distributed synchronous condenser cluster collaborative control system and method, which can integrate wide-area measurement information with advanced control algorithms to realize the collaborative operation of distributed synchronous condenser clusters, and can quickly suppress system oscillations and improve power grid stability.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In one aspect, a wide-area distributed synchronous condenser cluster collaborative control system includes:

[0008] The collaborative control master station is deployed at the power grid dispatching end. Its hardware platform includes redundantly configured servers and high-speed data exchange modules, which are used to receive real-time power grid operation data from the wide-area measurement system and generate wide-area collaborative control commands. The real-time power grid operation data includes at least the voltage amplitude, voltage phase angle and frequency of key power grid nodes. The wide-area collaborative control commands include reactive power adjustment commands and operation mode switching commands.

[0009] At least two local control substations of synchronous condensers are deployed in power plants in different geographical locations and are connected to the collaborative control master station. The substations are integrated into the distributed control system of the power plant and are used to receive and execute the wide-area collaborative control commands to control the synchronous condensers to complete the specified reactive power output or operating mode switching operations.

[0010] A wide-area measurement system, which is communicatively connected to the collaborative control master station, is used to provide real-time operation data of the power grid;

[0011] The local control substation of the synchronous condenser is connected to the excitation control system, static frequency converter unit, prime mover control system and protection system of the synchronous condenser body through the plant internal bus. The synchronous condenser is modified from the generator of the thermal power unit and can switch between power generation mode and phase regulation mode.

[0012] Furthermore, the local control substation of the synchronous condenser also includes a one-button start / stop control module, which is configured as follows:

[0013] Receive a sequence of start or stop commands from the collaborative control master station or local operator;

[0014] Automatically calls the excitation control interface, static frequency converter control interface, prime mover valve control interface, circuit breaker control interface and cooling system control interface in a preset logical sequence;

[0015] During the execution of the instruction sequence, key parameters of the unit are monitored in real time. If any parameter exceeds the limit, the current operation is automatically interrupted and a reverse safety sequence is executed or protection is triggered.

[0016] After completing all operations, the final status signal is fed back to the collaborative control master station.

[0017] On the other hand, a method for collaborative control of a wide-area distributed synchronous condenser cluster includes the following steps:

[0018] The collaborative control master station receives real-time power grid operation data from the wide-area measurement system;

[0019] The collaborative control master station determines the stability of the power grid based on the real-time operation data of the power grid and generates wide-area collaborative control commands.

[0020] The collaborative control master station sends the wide-area collaborative control command to the local control substations of the synchronous condensers distributed in different plants;

[0021] The local control substation of the synchronous condenser executes the wide-area collaborative control command to control the synchronous condenser to complete the specified reactive power output or operating mode switching operation.

[0022] The operation mode switching operation is used to control the synchronous condenser to seamlessly switch between power generation mode and phase modulation mode.

[0023] Furthermore, the generation of wide-area collaborative control commands by the collaborative control master station based on real-time power grid operation data specifically includes:

[0024] Construct a multivariate objective function with the optimization objectives of minimizing grid voltage deviation and maximizing system damping;

[0025] The multivariate objective function is solved by a cooperative control algorithm based on improved multi-agent reinforcement learning, and the optimal set of reactive power output settings for each synchronous condenser is obtained.

[0026] The optimal set of reactive power output settings is encapsulated into the reactive power adjustment command.

[0027] The value function update formula for the improved multi-agent reinforcement learning cooperative control algorithm is as follows:

[0028]

[0029] in, Indicates the state of the power grid Lower the camera Take action The value function, This represents a global state-space vector composed of real-time power grid operation data. Indicates adjusting the camera The reactive power output action, Indicates the learning rate. Indicates adjusting the camera The instantaneous reward signal obtained is determined by both the grid voltage deviation and the power oscillation mode. Indicates the discount factor. Indicates the state of the power grid at the next moment. Indicates the next state The maximum expected value that can be obtained is The collaboration coefficient represents the degree of influence of other agents' value functions on the current agent's decision. This indicates all other camera adjustments. Value function of camera The sum of the partial derivatives of the motion is used to quantize the camera adjustment. The impact of actions on the overall performance of the cluster.

[0030] Furthermore, the local control substation of the synchronous condenser executes the operating mode switching command to control the synchronous condenser to complete the operating mode switching operation, specifically including:

[0031] When the instruction is to switch from generation mode to phase modulation mode, the local control substation of the synchronous condenser controls the prime mover valve to close, reducing the active power output to zero, while maintaining the excitation system to work, keeping the terminal voltage stable, and realizing the decoupled control of active power and reactive power until the unit enters steady-state phase modulation operation;

[0032] When the instruction is to switch from phase modulation mode to generation mode, the local control substation of the synchronous condenser controls the prime mover valve to open, increasing the active power output, and at the same time dynamically adjusts the excitation current to stabilize the reactive power output, so as to achieve a smooth transition to generation mode.

[0033] The mode switching process is achieved by a fuzzy PID controller preset in the local control substation of the synchronous condenser. The controller takes the unit speed deviation and power angle deviation as inputs and the excitation voltage reference value and the prime mover valve opening command as outputs.

[0034] Furthermore, before the synchronous condenser is started and connected to the grid, the method also includes a step to improve the success rate of the static frequency converter's first-time commissioning:

[0035] After receiving the grid connection command, the local control substation of the synchronous condenser coordinates the control of the static frequency converter unit and the excitation system unit.

[0036] The static inverter unit outputs a frequency conversion current to drive the synchronous condenser rotor to accelerate to the predetermined overspeed point of the rated speed.

[0037] The excitation system unit controls the excitation to be activated in a timely manner during the speed increase process to establish the terminal voltage;

[0038] After the rotational speed reaches the predetermined overspeed point, the output of the static inverter unit is cut off, and the synchronous condenser enters the coasting state.

[0039] Based on the amplitude difference, frequency difference, and phase difference between the terminal voltage and the grid voltage, a synchronous grid connection algorithm based on adaptive sliding mode control is used to calculate the closing lead time command.

[0040] The closing command is issued at the optimal closing time to complete the grid connection operation;

[0041] The predetermined overspeed point is 105% of the rated speed.

[0042] Furthermore, the reactive power capacity of the synchronous condenser is improved through a minimal modification scheme, which includes:

[0043] Increase the maximum output voltage of the excitation system and increase the potential reactive power output capacity of the synchronous condenser;

[0044] The generator slip ring structure was modified by adopting a segmented guide ring design to increase the effective contact area and heat dissipation capacity of the conductive ring, so as to carry a larger excitation current;

[0045] Strengthen the inter-turn insulation of the stator winding and use insulation materials with higher temperature resistance to allow for operation under higher conditions;

[0046] Increase the pressure of the stator cooling water system, increase the cooling water flow rate, modify the cooler structure, enhance heat dissipation efficiency, and ensure that the temperature rise of the stator windings and core remains within the allowable range after the rated reactive power capacity is increased.

[0047] Furthermore, the collaborative control master station and the local control substation of the synchronous condenser communicate through the power dispatch data network. The wide-area collaborative control commands and the synchronous condenser operating status data are encoded and transmitted using the IEC61850 protocol. The operating status data includes at least the terminal voltage, output reactive power, winding temperature, and operating mode.

[0048] Compared with existing technologies, this wide-area distributed synchronous condenser cluster collaborative control system and method has the following advantages:

[0049] I. This invention constructs a wide-area distributed synchronous condenser cluster collaborative control system, comprising a collaborative control master station, a synchronous condenser local control substation, and a wide-area measurement system. Combined with a collaborative control algorithm based on improved multi-agent reinforcement learning, it can determine the stable state of the power grid based on real-time power grid operation data and generate wide-area collaborative control commands. This allows for rapid response to instantaneous power grid disturbances, achieving collaborative control of the distributed synchronous condenser cluster. Consequently, it effectively suppresses low-frequency oscillations in the power grid, stabilizes the grid voltage, and solves the problems of existing technologies that focus on controlling a single device or rely on slow data, making it impossible to perform rapid and collaborative control of the wide-area distributed synchronous condenser cluster and cope with instantaneous power grid disturbances. This improves the stability of power grid operation.

[0050] Second, by setting a fuzzy PID controller in the local control substation of the synchronous condenser, adopting a synchronous grid connection algorithm based on adaptive sliding mode control, and optimizing the synchronous condenser modification scheme, this invention can achieve seamless switching between the synchronous condenser in power generation mode and phase regulation mode, improve the success rate of synchronous condenser startup and grid connection, and enhance the reactive power output capability of the synchronous condenser, thereby ensuring the long-term reliable operation of the synchronous condenser cluster, further meeting the dynamic reactive power support requirements of the power grid, and providing more comprehensive protection for the safe operation of the power grid.

[0051] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0053] Figure 1 This is a flowchart illustrating the collaborative control process of a wide-area distributed synchronous condenser cluster according to the present invention.

[0054] Figure 2 This is a schematic diagram of the operating mode switching control principle of a wide-area distributed synchronous condenser cluster collaborative control according to the present invention;

[0055] Figure 3 This is a diagram illustrating the wide-area distributed architecture of a wide-area distributed synchronous condenser cluster collaborative control system according to the present invention. Detailed Implementation

[0056] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0057] Example 1

[0058] like Figure 2 and Figure 3As shown, this embodiment discloses a specific implementation of a wide-area distributed synchronous condenser cluster collaborative control system, aiming to solve the problems of frequent voltage fluctuations, prominent low-frequency oscillations, and uncoordinated control of distributed synchronous condenser clusters in power grids with a high proportion of renewable energy. This embodiment deploys a collaborative control master station, at least two local control substations for synchronous condensers, and a wide-area measurement system. It combines an improved multi-agent reinforcement learning algorithm to generate wide-area collaborative control commands, utilizes a fuzzy PID controller to achieve seamless switching between generation and phase-shifting modes for the synchronous condensers, and improves the grid connection success rate through an adaptive sliding mode grid connection algorithm for static frequency converters. Simultaneously, it optimizes the reactive power capacity modification scheme for the synchronous condensers, ultimately achieving enhanced dynamic reactive power support and stability of the power grid, meeting the millisecond-level response requirements of the power grid.

[0059] The wide-area distributed synchronous condenser cluster collaborative control system described in this embodiment is applied to a regional power grid containing large-scale wind power and photovoltaic power (the total installed capacity of wind power and photovoltaic power in this regional power grid accounts for more than 40% of the total installed capacity of the region). This regional power grid covers three thermal power plants in different geographical locations (located in the eastern, central and western regions of the regional power grid, respectively). Each thermal power plant has converted one of its existing 300MW thermal power units into a synchronous condenser, forming a distributed synchronous condenser cluster consisting of three synchronous condensers, which is used to cope with the grid voltage fluctuations and low-frequency oscillations caused by the fluctuations in the output of new energy sources.

[0060] System structure:

[0061] Collaborative Control Master Station: The collaborative control master station is deployed in the dispatch center of the power grid in this region. Its hardware platform adopts two redundant power dispatch dedicated servers (meeting the operation requirements of Class A sites in GB / T2887-2011 "General Specifications for Computer Sites", supporting dual-machine hot standby, and fault-free operation time ≥10000h) and one set of high-speed data exchange modules (transmission rate ≥1000Mbps, supporting parallel data transmission).

[0062] The main station establishes communication connections with the wide-area measurement system and three local control substations of synchronous condensers through the power dispatch data network (following DL / T5445-2010 "Technical Specifications for Power Dispatch Data Network"). Its core functions include:

[0063] It receives real-time power grid operation data uploaded by the wide-area measurement system. The data types cover the voltage amplitude, voltage phase angle and frequency of key power grid nodes (new energy grid connection points, load center nodes, synchronous condenser grid connection points). The data sampling period is consistent with that of the wide-area measurement system (50Hz).

[0064] Based on real-time power grid operation data, the stability of the power grid is determined, and wide-area collaborative control commands (including reactive power adjustment commands and operation mode switching commands) are generated.

[0065] The system receives operating status data (including terminal voltage, output reactive power, winding temperature, and operating mode) from the local control substations of each synchronous condenser. The operating status data is encoded and transmitted using the IEC61850 protocol to ensure standardized data format and reliable transmission.

[0066] Synchronous Condenser Local Control Substations: Three synchronous condenser local control substations are integrated into the distributed control systems (DCS) of the three thermal power plants, sharing hardware resources with the DCS but operating control logic independently to avoid mutual interference. Each substation communicates with the excitation control system, static frequency converter (SFC) unit, prime mover control system, and protection system of the corresponding synchronous condenser via the plant's internal bus (using industrial Ethernet, with a transmission delay of ≤10ms and supporting real-time data interaction).

[0067] Each substation is equipped with a one-button start / stop control module, the functions of which include:

[0068] Command reception: It can receive start / stop commands issued by the collaborative control master station or start / stop command sequences issued by local operators through the DCS human-machine interface;

[0069] Logical execution: Automatically calls the excitation control interface, SFC control interface, prime mover valve control interface, circuit breaker control interface and cooling system control interface in a preset logical sequence. For example, when starting up, the cooling system is started first, then the SFC is engaged to drive the rotor to accelerate, and finally the excitation is engaged.

[0070] Safety monitoring: During the execution of instructions, key parameters such as the speed of the synchronous condenser, terminal voltage, winding temperature, and bearing temperature are monitored in real time. If any parameter exceeds the preset allowable range (such as winding temperature exceeding 120℃ or speed deviation exceeding ±5% of rated speed), the current operation will be automatically interrupted and a reverse safety sequence will be executed (such as closing the prime mover valve, cutting off the excitation power supply, or starting the emergency cooling) or the protection system will be triggered (such as tripping and stopping the machine).

[0071] Status feedback: After completing all start-up and shutdown operations, the final operating status signal of the synchronous condenser is fed back to the collaborative control master station (such as "grid-connected ready", "phase-changing operation", "shutdown standby").

[0072] Wide-area measurement system: The wide-area measurement system adopts equipment based on synchronous phasor measurement technology. Phasor measurement units (PMUs) are deployed at key nodes of the power grid. The sampling frequency of the PMU is ≥50Hz and the time synchronization accuracy is ≤1μs (based on the Beidou satellite synchronization system). It can collect voltage amplitude, voltage phase angle and frequency data of key nodes of the power grid in real time, and upload the data to the collaborative control master station through a dedicated optical fiber communication link. The data transmission delay is ≤20ms, providing the collaborative control master station with high-precision and high-real-time basic data of power grid operation status.

[0073] Synchronous Condenser Retrofit: The synchronous condenser is a retrofit of the generator of an existing 300MW thermal power unit in a thermal power plant. The retrofit plan focuses on improving reactive power capacity and operational stability, and specifically includes:

[0074] Increase the maximum output voltage of the excitation system: Increase the maximum output voltage of the excitation system by 20% compared to the original design, thereby increasing the potential reactive power output capability of the synchronous condenser;

[0075] Modify the generator slip ring structure: Adopt a segmented guide ring design to increase the effective contact area of ​​the conductive ring (15% more than the original structure) and the heat dissipation area, thereby improving the slip ring's ability to carry large excitation currents.

[0076] Strengthen the inter-turn insulation strength of the stator winding: Select insulation material with a temperature resistance class of H (the original insulation material was class B), which allows the synchronous condenser to operate at higher operating temperatures;

[0077] Optimize the stator cooling water system: Increase the working pressure of the cooling water system from the original 0.3MPa to 0.5MPa, increase the cooling water flow rate (by 30%), and at the same time modify the cooler structure (adopting a high-efficiency finned cooler) to enhance heat dissipation efficiency and ensure that the temperature rise of the stator winding and core still meets the allowable range of GB / T755-2019 "Rated Electrical Machines Ratings and Performance" after the rated reactive capacity is increased.

[0078] Furthermore, the working principle of the wide-area distributed synchronous condenser cluster collaborative control system in this embodiment is as follows:

[0079] Receiving real-time power grid operation data: The collaborative control master station receives real-time voltage amplitude, voltage phase angle, and frequency data of key power grid nodes collected by the PMU through a dedicated communication link with the wide-area measurement system. The master station verifies the validity of the received data: outliers that are significantly beyond physical meaning (such as voltage amplitude exceeding ±20% of the rated voltage) are removed, and short-term missing data (missing duration ≤100ms) is supplemented using linear interpolation. Finally, a standardized set of real-time power grid operation data is formed for subsequent power grid stability assessment.

[0080] Generate wide-area collaborative control commands: Based on the verified real-time power grid operation data, the collaborative control master station first determines the stable state of the power grid: if the voltage deviation of key power grid nodes exceeds ±5% of the rated voltage, or the power grid frequency fluctuation exceeds ±0.2Hz, or low-frequency oscillations within the range of 0.2-2.5Hz are detected, the power grid is determined to be in an unstable state, and wide-area collaborative control commands need to be generated; if the power grid operating parameters are all within the above normal ranges, the power grid is determined to be in a stable state, and control commands are not generated temporarily.

[0081] The process of generating wide-area cooperative control instructions specifically includes:

[0082] The first step is to construct a multivariate objective function. With the optimization objectives of minimizing grid voltage deviation and maximizing system damping, the objective function expression is as follows:

[0083]

[0084] in, The value of the multivariate objective function; , Weighting coefficients ( Dynamically adjust according to the power grid operating status: when the voltage deviation is large. When the system damping is relatively small, a value of 0.6 is taken. Take 0.6); This represents the average absolute value of voltage deviation at key nodes in the power grid. is the system damping coefficient.

[0085] The second step is to solve the multivariate objective function. A cooperative control algorithm based on improved multi-agent reinforcement learning is used to solve the objective function, obtaining the optimal reactive power output setpoints for each synchronous condenser. In this algorithm, each synchronous condenser is treated as an agent, and its global state space vector... Composed of real-time power grid operation data (voltage amplitude, voltage phase angle, frequency), the actions of each intelligent agent To adjust the reactive power output of the camera, the value function update formula is as follows:

[0086]

[0087] in, Indicates the state of the power grid Lower the camera Take action The value function; The learning rate is set to 0.1-0.3, with 0.3 used in the early stages of iteration to speed up convergence and 0.1 used in the later stages of iteration to improve accuracy. To adjust the camera Instant reward signal (from grid voltage deviation) and power oscillation mode Decide, , , (This is the reward coefficient, all taken as 0.5). This is a discount factor (with a value of 0.9, balancing current and future rewards). The state of the power grid at the next moment; To adjust the camera In the next state The maximum expected value that can be obtained; The coordination coefficient (valued at 0.1, adjusting the influence of other agents on the current agent's decision-making); For other camera adjustment Value function of camera The sum of partial derivatives of the motion, quantized adjustment camera The impact of actions on the overall performance of the cluster.

[0088] The third step is to encapsulate the instructions. The set of optimal reactive power output settings for each synchronous condenser obtained from the solution is encapsulated into reactive power adjustment instructions; if it is necessary to switch the operating mode of the synchronous condenser, an operating mode switching instruction is generated, and the instruction format follows the relevant standards in the IEC61850 specification.

[0089] Issuance of wide-area collaborative control commands: The collaborative control master station issues the generated wide-area collaborative control commands (reactive power adjustment commands or operating mode switching commands) to the local control substations of each synchronous condenser through the power dispatch data network. The command transmission adopts an IPSec-based encryption protocol to prevent commands from being tampered with or stolen; the transmission delay is controlled within 50ms to meet the millisecond-level response requirements of the power grid to instantaneous disturbances.

[0090] Executing Wide Area Cooperative Control Commands: After receiving the wide area cooperative control commands, the local control substation of the synchronous condenser parses the command content and executes the corresponding operations, specifically including:

[0091] Executing reactive power regulation commands: The substation analyzes the optimal reactive power output setpoint in the command and sends an excitation current regulation signal to the synchronous condenser excitation control system via the plant's internal bus. The excitation control system adjusts the current in the excitation winding based on this signal, thereby controlling the synchronous condenser to output the specified reactive power. During regulation, the substation monitors the synchronous condenser's terminal voltage and output reactive power in real time, ensuring through closed-loop control that the deviation between the actual output value and the setpoint is ≤ ±2%.

[0092] Execution of operating mode switching command: When the command is "generation mode → phase modulation mode" switching, the substation controls the prime mover control system to slowly close the prime mover valve (valve closing rate is 0.05% / ms), gradually reducing the active power output of the synchronous condenser to zero; at the same time, it controls the excitation control system to maintain the excitation current stable and keep the generator terminal voltage within the range of 98%-102% of the rated voltage, realizing the decoupling control of active power and reactive power; after the active power drops to zero and the generator terminal voltage stabilizes, the unit enters steady-state phase modulation operation. The entire switching process lasts ≤30s, and the voltage fluctuation is ≤±3%.

[0093] When the instruction is to switch from "phase adjustment mode to power generation mode", the substation controls the prime mover control system to slowly open the prime mover valve (valve opening rate is 0.03% / ms) and gradually increase the active power output; at the same time, it controls the excitation control system to dynamically adjust the excitation current to ensure stable reactive power output (actual output deviation from set value ≤ ±2%); when the active power rises to the target value (set according to grid load demand) and the frequency stabilizes at 50±0.1Hz, the smooth transition to power generation mode is completed, and the entire switching process lasts ≤40s.

[0094] The above mode switching process is implemented by a fuzzy PID controller pre-installed in the substation: the controller takes the speed deviation (the difference between the actual speed and the rated speed) and power angle deviation (the difference between the actual power angle and the rated power angle) of the synchronous condenser as inputs, and after fuzzification, fuzzy inference (using Mamdani inference rules) and defuzzification processing, it outputs the excitation voltage reference value and the prime mover valve opening command, which control the excitation system and the prime mover control system respectively, ensuring that the switching process is smooth and shock-free.

[0095] Static inverter grid connection operation: Before starting grid connection, the substation performs steps to improve the success rate of static inverter first-time commissioning:

[0096] Coordinated control: After receiving the grid connection command, the substation synchronously sends coordinated control signals to the SFC unit and the excitation system unit;

[0097] Speed ​​increase: Control the SFC unit to output frequency converter current, drive the synchronous condenser rotor to accelerate to 105% of the rated speed (predetermined overspeed point).

[0098] Excitation activation: When the speed rises to 80% of the rated speed, the excitation system unit is activated to gradually build up the terminal voltage to the rated value;

[0099] SFC cut-off: When the speed reaches 105% of the rated speed, the output current of the SFC unit is cut off, and the synchronous condenser enters the coasting state.

[0100] Synchronous grid connection: Based on the amplitude difference, frequency difference, and phase difference between the generator terminal voltage and the grid voltage, a synchronous grid connection algorithm based on adaptive sliding mode control is used to calculate the closing lead time command (dynamically adjusted according to the difference, ranging from 0.1 to 0.3 seconds); at the optimal closing time, a closing command is sent to the circuit breaker control interface to complete the grid connection operation. The grid connection success rate of this step is ≥99.5% according to the test.

[0101] In summary, this embodiment constructs a three-tiered wide-area distributed synchronous condenser cluster collaborative control system consisting of a "collaborative control master station - local control substation - wide-area measurement system". It combines an improved multi-agent reinforcement learning algorithm to optimize the generation of control commands, utilizes a fuzzy PID controller to achieve seamless switching of operating modes, and employs an adaptive sliding mode grid connection algorithm for static frequency converters and a reactive power capacity modification scheme for synchronous condensers. This effectively solves the problems of uncoordinated control, slow response speed, low grid connection success rate, and insufficient reactive power support capacity in existing technologies for synchronous condenser clusters.

[0102] Practical application tests show that the system can control the grid voltage deviation within ±3%, shorten the low-frequency oscillation suppression time to within 0.5s, and reduce the voltage fluctuation during the synchronous condenser mode switching process to ≤±3% and the frequency fluctuation to ≤±0.1Hz. It can provide reliable dynamic reactive power support for grids with a high proportion of new energy sources, significantly improve the grid's ability to cope with the output fluctuations of new energy sources and the overall operational stability, fully meet the technical requirements for the construction of new power systems, and has good engineering application value.

[0103] Example 2

[0104] like Figure 1 As shown in Example 1, this example elaborates on the specific steps of a wide-area distributed synchronous condenser cluster collaborative control method during operation. The specific steps are as follows:

[0105] 1. System initialization and data preparation:

[0106] The collaborative control master station starts up and completes the self-test of the communication link with the Wide Area Measurement System (WAMS) and the local control substations of each synchronous condenser;

[0107] The main station receives real-time power grid operation data uploaded by WAMS, including voltage, phase angle and frequency of key nodes;

[0108] Perform validity checks and preprocessing on the data, remove outliers, and fill in short-term missing data.

[0109] 2. Power grid stability assessment:

[0110] Based on the preprocessed data, the main station determines whether the power grid is in a stable state;

[0111] If voltage deviation exceeds the limit, frequency fluctuation or low frequency oscillation is detected, it is determined to be an unstable state, triggering the collaborative control command generation process;

[0112] If the power grid operating parameters are normal, the monitoring status will continue and no control commands will be initiated.

[0113] 3. Generation of coordinated control commands:

[0114] The main station constructs a multivariate optimization function with the objectives of minimizing voltage deviation and maximizing system damping;

[0115] An improved multi-agent reinforcement learning algorithm is used to calculate the optimal reactive power output setpoint for each synchronous condenser.

[0116] Generate reactive power adjustment commands or operating mode switching commands, and encapsulate and encode the commands.

[0117] 4. Instruction Issuance and Reception:

[0118] The main station sends instructions to the local control substations of each synchronous condenser through the power dispatch data network;

[0119] Command transmission uses an encryption protocol to ensure security and real-time performance, with transmission latency controlled within 50ms;

[0120] After receiving the instruction, the substation parses and verifies it, and prepares to execute the corresponding operation.

[0121] 5. Instruction Execution and Local Control:

[0122] If it is a reactive power regulation command, the substation adjusts the excitation current through the excitation control system to achieve precise reactive power output;

[0123] If it is an operation mode switching command, the substation starts the fuzzy PID controller to coordinate the prime mover and the excitation system to achieve a smooth switch between the power generation mode and the phase regulation mode;

[0124] The substation monitors the unit's operating status in real time, and if any parameters exceed the limits, it will initiate a safety sequence or protection action.

[0125] 6. Grid connection operation (if startup process is involved):

[0126] The substation controls the static frequency converter (SFC) unit to drive the rotor to accelerate to the overspeed point;

[0127] During the speed increase process, excitation is applied in a timely manner to establish the terminal voltage;

[0128] An adaptive sliding mode control algorithm is used to calculate the closing timing and complete the grid connection operation.

[0129] 7. Status Feedback and Closed-Loop Update:

[0130] The substation will send the command execution results and unit operating status data back to the main station;

[0131] The master station updates the power grid state estimation and control strategy based on the feedback information, forming a closed-loop control.

[0132] Continuously monitor the power grid status and initiate a new round of control commands as needed.

[0133] The method of this invention can quickly respond to grid disturbances, synergistically suppress low-frequency oscillations, stabilize voltage, improve the operational reliability of synchronous condensers, and provide stable support for new power systems.

[0134] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for collaborative control of a wide-area distributed synchronous condenser cluster, characterized in that, Includes the following steps: The collaborative control master station receives real-time power grid operation data from the wide-area measurement system. The real-time power grid operation data includes at least the voltage amplitude, voltage phase angle, and frequency of key nodes in the power grid. The collaborative control master station determines the stability of the power grid based on the real-time operation data of the power grid and generates wide-area collaborative control commands, wherein the generation of wide-area collaborative control commands includes: Construct a multivariate objective function with the optimization objectives of minimizing grid voltage deviation and maximizing system damping; The multivariate objective function is solved using a cooperative control algorithm based on improved multi-agent reinforcement learning, yielding the optimal reactive power output setpoints for each synchronous condenser. The value function update formula for the improved multi-agent reinforcement learning cooperative control algorithm is as follows: in, Indicates the state of the power grid Lower the camera Take action The value function, This represents a global state-space vector composed of real-time power grid operation data. Indicates adjusting the camera The reactive power output action, Indicates the learning rate. Indicates adjusting the camera The instantaneous reward signal obtained is determined by both the grid voltage deviation and the power oscillation mode. Indicates the discount factor. Indicates the state of the power grid at the next moment. Indicates the next state The maximum expected value that can be obtained is The collaboration coefficient represents the degree of influence of other agents' value functions on the current agent's decision. This indicates all other camera adjustments. Value function of camera The sum of the partial derivatives of the motion is used to quantize the camera adjustment. The impact of actions on the overall performance of the cluster; The optimal set of reactive power output settings is encapsulated into the reactive power adjustment command. The collaborative control master station sends the wide-area collaborative control command to the local control substations of synchronous condensers distributed in different plants; The local control substation of the synchronous condenser executes the wide-area collaborative control command to control the synchronous condenser to complete the specified reactive power output or operating mode switching operation; the operating mode switching operation is used to control the synchronous condenser to seamlessly switch between the power generation mode and the phase modulation mode.

2. The method for collaborative control of a wide-area distributed synchronous condenser cluster according to claim 1, characterized in that, The collaborative control master station, the local control substation of the synchronous condenser, and the wide-area measurement system constitute a wide-area distributed synchronous condenser cluster collaborative control system, wherein: The collaborative control master station is deployed at the power grid dispatching terminal. Its hardware platform includes redundantly configured servers and high-speed data exchange modules, which are used to receive real-time power grid operation data from the wide-area measurement system and generate wide-area collaborative control instructions. The wide-area collaborative control instructions include reactive power adjustment instructions and operating mode switching instructions. The synchronous condenser has at least two local control substations, which are deployed in power plants in different geographical locations and are connected to the collaborative control master station. The substations are integrated into the power plant's distributed control system and are used to receive and execute the wide-area collaborative control commands to control the synchronous condenser to complete the specified reactive power output or operating mode switching operations. The wide-area measurement system is communicatively connected to the collaborative control master station and is used to provide real-time operation data of the power grid; The local control substation of the synchronous condenser is connected to the excitation control system, static frequency converter unit, prime mover control system and protection system of the synchronous condenser body through the plant internal bus. The synchronous condenser is modified from the generator of the thermal power unit and can switch between power generation mode and phase regulation mode.

3. The method for collaborative control of a wide-area distributed synchronous condenser cluster according to claim 2, characterized in that, The local control substation of the synchronous condenser also includes a one-button start / stop control module, which is configured as follows: Receive a sequence of start or stop commands from the collaborative control master station or local operator; Automatically calls the excitation control interface, static frequency converter control interface, prime mover valve control interface, circuit breaker control interface and cooling system control interface in a preset logical sequence; During the execution of the instruction sequence, key parameters of the unit are monitored in real time. If any parameter exceeds the limit, the current operation is automatically interrupted and a reverse safety sequence is executed or protection is triggered. After completing all operations, the final status signal is fed back to the collaborative control master station.

4. The method for collaborative control of a wide-area distributed synchronous condenser cluster according to claim 1, characterized in that, The local control substation of the synchronous condenser executes the operating mode switching command to control the synchronous condenser to complete the operating mode switching operation, specifically including: When the instruction is to switch from generation mode to phase modulation mode, the local control substation of the synchronous condenser controls the prime mover valve to close, reducing the active power output to zero, while maintaining the excitation system to work, keeping the terminal voltage stable, and realizing the decoupled control of active power and reactive power until the unit enters steady-state phase modulation operation; When the instruction is to switch from phase modulation mode to generation mode, the local control substation of the synchronous condenser controls the prime mover valve to open, increasing the active power output, and at the same time dynamically adjusts the excitation current to stabilize the reactive power output, so as to achieve a smooth transition to generation mode. The mode switching process is achieved by a fuzzy PID controller preset in the local control substation of the synchronous condenser. The controller takes the unit speed deviation and power angle deviation as inputs and the excitation voltage reference value and the prime mover valve opening command as outputs.

5. The method for collaborative control of a wide-area distributed synchronous condenser cluster according to claim 1, characterized in that, Before the synchronous condenser is started and connected to the grid, the method further includes a step to improve the success rate of the static frequency converter's first-time commissioning: After receiving the grid connection command, the local control substation of the synchronous condenser coordinates the control of the static frequency converter unit and the excitation system unit. The static inverter unit outputs a frequency conversion current to drive the synchronous condenser rotor to accelerate to the predetermined overspeed point of the rated speed. The excitation system unit controls the excitation to be activated in a timely manner during the speed increase process to establish the terminal voltage; After the rotational speed reaches the predetermined overspeed point, the output of the static inverter unit is cut off, and the synchronous condenser enters the coasting state. Based on the amplitude difference, frequency difference, and phase difference between the terminal voltage and the grid voltage, a synchronous grid connection algorithm based on adaptive sliding mode control is used to calculate the closing lead time command. The closing command is issued at the optimal closing time to complete the grid connection operation; The predetermined overspeed point is 105% of the rated speed.

6. The method for collaborative control of a wide-area distributed synchronous condenser cluster according to claim 1, characterized in that, The reactive power capacity of the synchronous condenser is increased through a minimal modification scheme, which includes: Increase the maximum output voltage of the excitation system and increase the potential reactive power output capacity of the synchronous condenser; The generator slip ring structure was modified by adopting a segmented guide ring design to increase the effective contact area and heat dissipation capacity of the conductive ring, so as to carry a larger excitation current; Strengthen the inter-turn insulation of the stator winding and use insulation materials with higher temperature resistance to allow for operation under higher conditions; Increase the pressure of the stator cooling water system, increase the cooling water flow rate, modify the cooler structure, enhance heat dissipation efficiency, and ensure that the temperature rise of the stator windings and core remains within the allowable range after the rated reactive power capacity is increased.

7. The method for collaborative control of a wide-area distributed synchronous condenser cluster according to claim 1, characterized in that, The collaborative control master station and the local control substation of the synchronous condenser communicate through the power dispatch data network. The wide-area collaborative control commands and the synchronous condenser operating status data are encoded and transmitted using the IEC61850 protocol. The operating status data includes at least the terminal voltage, output reactive power, winding temperature, and operating mode.

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