Multi-time scale reactive power resource fusion coordination control system

Abstract

The invention relates to the technical field of power grid reactive power control, in particular to a multi-time scale reactive power resource fusion coordination control system, which comprises a resource acquisition module, a fusion modeling module and a coordination execution module. The resource acquisition module acquires running state data of various reactive resources such as a phase modifier and a low-voltage capacitor, and constructs a multi-time scale model which takes the phase modifier as a core and contains transient, transition and steady state parameters; the fusion modeling module configures millisecond-level, second-level and minute-level control time sequences to form a full-time chain control framework; the coordination execution module realizes control in stages, triggers the phase modifier to quickly support voltage in a transient stage, coordinates various types of resources in turns in a transition stage, and completes resource reset and reactive power reserve recovery of the phase modifier in a steady state stage. According to the system, the low-voltage suspension phenomenon of the near-area transformer substation after a fault can be relieved, voltage fluctuation is avoided, and full-time chain efficient utilization of reactive power resources and consistency and stability of reactive power control are achieved.

Description

Technical Field

[0001] This invention relates to the field of reactive power control technology for power grids, and in particular to a multi-timescale reactive power resource fusion and coordination control system. Background Technology

[0002] In power grid operation, the stable control of reactive power is an important support for ensuring grid voltage stability and improving power supply reliability. At present, various reactive resources such as synchronous condensers, low-voltage capacitors, low-voltage reactors, and generators have been deployed in the power grid. Existing technologies mostly adopt independent control or simple combination control of single types of reactive resources. There is a lack of a unified modeling and control framework for reactive power regulation needs at different time scales. Usually, control strategies are designed only for a single stage in transient, transition or steady state, and a collaborative control mechanism covering the entire time chain has not been formed.

[0003] In existing technologies, synchronous condensers are mostly used only for voltage support during transient phases. The switching of low-voltage capacitors and reactors is mostly controlled by fixed timing, without precise coordination with the reactive power output of the synchronous condenser. This leads to a tendency for substations in the vicinity to experience low-voltage floating states after a fault. Furthermore, after the transition phase ends, the mobilized reactive power resources cannot be reset in a timely manner, and the dynamic reactive power reserve of the synchronous condenser is difficult to recover quickly. This makes it impossible to achieve efficient utilization of reactive power resources across multiple time scales. At the same time, the operating status data of various types of reactive power resources are not effectively integrated, making it difficult to form a precise control basis and failing to meet the requirements of voltage stability control throughout the entire power grid process. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a multi-timescale reactive resource fusion and coordination control system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a multi-time-scale reactive power resource fusion and coordination control system, comprising: The resource acquisition module acquires the operating status data of synchronous condensers, low-voltage capacitors, low-voltage reactors and generators deployed in the power grid, and constructs a multi-timescale model of a multi-type reactive power resource fusion system with the synchronous condensers as the core, including transient response parameters, transient process adjustment parameters and steady-state optimization parameters. The fusion modeling module, based on the multi-timescale model of the multi-type reactive resource fusion system, configures control timing sequences at the millisecond, second, and minute levels respectively, forming a full-time chain control framework covering the transient process stage, the transition process stage, and the steady-state process stage. The coordinated execution module, during the transient process phase, triggers the autonomous response control of the synchronous condenser based on the transient response parameters, enabling it to rapidly output reactive current to support the grid voltage according to the transient characteristics of the generator terminal voltage. During the transition process phase, it initiates a coordinated control mechanism for multiple types of reactive resources based on the transition process adjustment parameters. In response to the low-voltage floating state that occurs in the nearby substation after a fault, it adjusts the reactive current output by the synchronous condenser and the switching status of the low-voltage capacitors and low-voltage reactors in the nearby substation in stages. During the steady-state phase, it initiates the optimization command of the automatic voltage control system based on the steady-state optimization parameters, resets the capacity of the low-voltage capacitors and low-voltage reactors called up during the transition process phase, and restores the dynamic reactive power reserve of the synchronous condenser, completing a complete multi-timescale closed-loop control.

[0006] As a further aspect of the present invention, a multi-time-scale model for a multi-type reactive power resource fusion system is constructed, including: Collect the stator winding parameters, excitation system response rate, and cooling system limitation curve of the synchronous condenser, and establish an electromagnetic transient response sub-model of the synchronous condenser on a millisecond time scale. The rated capacity, mechanical switching delay, and harmonic tolerance of the low-voltage capacitor and the low-voltage reactor are collected to establish a discrete adjustment sub-model of the low-voltage capacitor and the low-voltage reactor on a second-level time scale. The generator's power angle characteristic curve, excitation regulator parameters, and prime mover power constraints are collected to establish a continuous regulation sub-model of the generator on a minute-level time scale. The electromagnetic transient response sub-model, the discrete regulation sub-model, and the continuous regulation sub-model are coupled together, and the admittance matrix of the power grid topology is introduced as an external constraint to generate a multi-timescale model of the multi-type reactive power resource fusion system that simultaneously reflects the dynamic characteristics and response characteristics of the power grid voltage stability.

[0007] As a further aspect of the present invention, based on the multi-time-scale model of the multi-type reactive power resource fusion system, control timing sequences at the millisecond, second, and minute levels are configured respectively, including: The time constants of each sub-model in the multi-time-scale model of the multi-type reactive power resource fusion system are analyzed, and the response delay of the synchronous condenser, the action cycle of the low-voltage capacitor switching mechanism, and the adjustment cycle of the automatic voltage control system are extracted. The scan period of the millisecond-level control timing is set to a fixed value. The millisecond-level control timing is only associated with the excitation voltage setpoint of the synchronous condenser and is used to capture the initial voltage drop waveform after a fault occurs. The scanning period of the second-level control timing is set to be greater than that of the millisecond-level control timing. The second-level control timing is associated with the reactive power output setting value of the synchronous condenser and the switching status words of the low-voltage capacitor and the low-voltage reactor. The scan period of the minute-level control timing is set to be greater than that of the second-level control timing, and the minute-level control timing is associated with the global voltage reference value and the reactive power optimization instruction queue of the automatic voltage control system. The configured millisecond-level control timing, second-level control timing, and minute-level control timing are embedded into the unified scheduling engine to ensure that control commands at the three time scales are executed serially without conflict on the time axis.

[0008] As a further aspect of the present invention, during the transient process phase, the autonomous response control of the synchronous condenser is triggered based on the transient response parameters, including: Real-time monitoring of the instantaneous terminal voltage value at the synchronous condenser access point, and calculation of the per-unit deviation of the instantaneous terminal voltage value relative to the rated voltage; When the per-unit deviation is lower than the preset voltage collapse threshold, the built-in strong excitation control module of the synchronous condenser is activated to release the normal restrictions of the synchronous condenser excitation system. The excitation current of the synchronous condenser is forcibly increased to a maximum value and maintained for a predetermined time window, thereby forcing the synchronous condenser to inject maximum inductive reactive current into the power grid. During the autonomous response of the synchronous condenser, any reactive power adjustment commands issued by the second-level control timing are blocked until the instantaneous value of the generator terminal voltage recovers to above the set safety threshold value.

[0009] As a further aspect of the present invention, during the transition process phase, a coordinated control mechanism for multiple types of reactive power resources is initiated based on the transition process adjustment parameters, including: After the transient process ends, the voltage recovery curves of each node in the power grid at the current moment are read, and the list of nearby substations in the low voltage floating state is identified. Based on the reactive power demand gap calculation rules in the transition process adjustment parameters, the reactive power compensation increment required for each near-area substation in the low-voltage floating state is calculated respectively. Prioritize adjusting the reactive power output setting value of the synchronous condenser to make it bear the main share of the reactive power compensation increment, and record the current reactive power margin of the synchronous condenser; If the reactive power margin of the synchronous condenser is insufficient to fill the remaining reactive power compensation increment, an input command for the low-voltage capacitor or an output command for the low-voltage reactor is generated, and the discrete capacity of the low-voltage capacitor and the low-voltage reactor is used to make up the difference. The list of nearby substations is sorted according to the urgency of voltage restoration, and reactive power allocation and equipment adjustment steps are performed sequentially until all the low voltage floating states are eliminated.

[0010] As a further aspect of the present invention, the step of adjusting the reactive current output by the synchronous condenser and the switching status of the low-voltage capacitors and low-voltage reactors within the nearby substation in stages to address the low-voltage floating state that occurs after a fault in the nearby substation includes: The first round of the phased adjustment is defined as the emergency support round, in which the reactive power output of the synchronous condenser is increased to the maximum allowable value only when the synchronous condenser has not reached its thermal stability limit. The second round of the phased adjustment is defined as the refined compensation round. If the grid voltage still does not meet the standard after the first round is completed, the switching combination of the low-voltage capacitor and the low-voltage reactor will be calculated. Based on the current power factor level of the power grid, determine whether it is necessary to put the low-voltage capacitor into operation to increase capacitive reactive power, or to put the low-voltage reactor into operation to offset the excess capacitive reactive power. Generate specific switching action commands to control the circuit breaker of the low-voltage capacitor or the low-voltage reactor to close, and wait for a complete power frequency cycle after each action to observe the voltage feedback. The judgment and action of the second round are executed repeatedly until the grid voltage stabilizes within the preset normal fluctuation range.

[0011] As a further aspect of the present invention, during the steady-state process phase, an optimization command for the automatic voltage control system is initiated based on the said steady-state optimization parameters, including: After all adjustment operations are completed during the transition phase, the current reactive power resource status snapshot is frozen. The status snapshot includes the real-time reactive power output of the synchronous condenser, the number of low-voltage capacitor banks connected, and the number of low-voltage reactor banks disconnected. Switch the automatic voltage control system to optimization mode and read the economic dispatch weight factor in the steady-state optimization parameters; With minimizing the network loss and maximizing the dynamic reactive power reserve of the synchronous condenser as dual objectives, the adjustment cost function of the low-voltage capacitor and the low-voltage reactor is constructed. Solving the adjustment cost function yields a set of optimal switching state combinations that allow the synchronous condenser to exit the auxiliary support state and return to the economic operating range; The control command corresponding to the optimal switching state combination is issued to disconnect the over-energized low-voltage capacitor or re-energize the over-deactivated low-voltage reactor, thereby releasing the standby capacity of the synchronous condenser.

[0012] As a further aspect of the present invention, the low-voltage capacitors and low-voltage reactors invoked during the transition process are recharged, and the dynamic reactive power reserve of the synchronous condenser is restored, including: Check the differences between the optimal switching state combination issued by the automatic voltage control system and the current actual switching state; A trip command is sent only to the low-voltage capacitor with the discrepancy, or a closing command is sent only to the low-voltage reactor with the discrepancy, in order to avoid unnecessary switching operations. After each successful state change operation of the low-voltage capacitor or the low-voltage reactor, the terminal voltage and reactive load data of the synchronous condenser are immediately read. Based on the latest grid voltage level, the excitation current setting value of the synchronous condenser is linearly reduced so that it gradually unloads the excess reactive load it bears during the transition process; The rotor current and stator temperature of the synchronous condenser are continuously monitored to ensure that no equipment protection limits are triggered during the process of restoring the dynamic reactive power reserve.

[0013] As a further aspect of the present invention, it also includes: The control and coordination module, when switching from the transient process stage to the transition process stage, transmits the peak reactive power output value and duration recorded by the synchronous condenser during the autonomous response period to the coordination control mechanism of the transition process stage as the initial boundary conditions for the transition process adjustment parameters. When switching from the transition process stage to the steady-state process stage, the final switching state of the low-voltage capacitor and the low-voltage reactor, as well as the final voltage distribution data of the power grid, are packaged and sent to the automatic voltage control system as input variables for the steady-state optimization parameters. Before the steady-state process ends and the next monitoring cycle begins, a control closed-loop report containing key indicators on three time scales is generated. The control closed-loop report records the response time of the synchronous condenser, the number of times the low-voltage capacitor and the low-voltage reactor operate, and the steady-state deviation of the entire network voltage. The data in the control closed-loop report is written back to the multi-time-scale model of the multi-type reactive power resource fusion system to correct the lag parameters in the model in order to adapt to the slow drift of the power grid operating conditions.

[0014] As a further aspect of the present invention, it also includes: When the emergency control module detects an alarm signal of commutation failure at the inverter station of the DC transmission system in the power grid, it immediately interrupts the current control process and forcibly switches to the high-voltage, high-capacity reactive power support mode for commutation failure. In the high-voltage, high-capacity reactive power support mode, the steady-state optimization parameters and economic dispatch weight factors are ignored, and the reactive power output of the synchronous condenser is directly locked to the preset maximum output value. At the same time, instructions are sent to multiple sets of low-voltage capacitors in the vicinity of the DC transmission system to be put into operation simultaneously, so as to make up for the reactive power deficit caused by commutation failure by utilizing the instantaneous large capacity characteristics of the low-voltage capacitors. The high-voltage, high-capacity reactive power support mode is maintained until the power recovery command of the DC transmission system is issued. Then, the low-voltage capacitors are withdrawn in sequence according to the normal timing, and the reactive power output of the synchronous condenser is gradually reduced, smoothly transitioning back to the conventional multi-timescale control process.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: A multi-timescale model of a reactive power resource fusion system is constructed, centered on a synchronous condenser and integrating three types of parameters: transient response parameters, transient process adjustment parameters, and steady-state optimization parameters. This model covers multiple types of reactive power resources, including synchronous condensers, low-voltage capacitors, low-voltage reactors, and generators. It is configured with three levels of control timing: millisecond, second, and minute. This forms a full-time chain control framework covering the entire transient, transient, and steady-state process. This breaks through the limitations of conventional single-timescale control and independent modeling of single resources, achieving comprehensive fusion of operational data from multiple types of reactive power resources. It allows for precise matching of control requirements at different time scales, forming an organic whole of control strategies at each stage. This avoids the problem of disconnect between single-stage control and overall control requirements, and realizes the orderly scheduling and efficient utilization of reactive power resources across the entire time chain.

[0016] During the transition phase, to address the low-voltage floating state that occurs in nearby substations after a fault, the reactive current output by the synchronous condenser and the switching status of low-voltage capacitors and reactors within the nearby substation are coordinated and adjusted in rounds. During the steady-state phase, the capacity of the low-voltage capacitors and reactors called up during the transition phase is reset, and the dynamic reactive power reserve of the synchronous condenser is restored, forming a complete multi-timescale closed-loop control. This solves the problems of lack of coordination in multi-resource regulation during the transition phase and the inability to reset resources in a timely manner during the steady-state phase in conventional technologies. It can effectively alleviate the low-voltage floating phenomenon in nearby substations after a fault, avoid voltage fluctuations caused by reactive power resource imbalance, and enable reactive power resources to quickly return to standby status after the control ends, ensuring the responsiveness of reactive power regulation in subsequent grid operation and achieving the continuity and stability of reactive power control. Attached Figure Description

[0017] Figure 1 This is a timing diagram of the multi-timescale reactive resource fusion and coordination control system described in this invention. Figure 2 Flowcharts for configuring control timing sequences at the millisecond, second, and minute levels; Figure 3 The graph shows the changes in reactive power output and voltage of the synchronous condenser during the phased adjustment process. Figure 4 Optimize the trend chart for network loss and dynamic reactive power reserve; Figure 5 A bar chart showing the comparison of parameter corrections for reactive power resource models. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] See Figure 1 The resource acquisition module first acquires real-time operating status data of the synchronous condensers, low-voltage capacitors, low-voltage reactors, and generators deployed in the power grid. Based on this data, it constructs a multi-timescale model of a multi-type reactive power resource fusion system, centered on the synchronous condensers and including transient response parameters, transient process adjustment parameters, and steady-state optimization parameters. The fusion modeling module then configures corresponding control timing sequences at the millisecond, second, and minute levels based on this multi-timescale model, thereby forming a full-time chain control framework covering the transient process stage, the transient process stage, and the steady-state process stage. The coordinated execution module performs control based on this framework. During the transient process, it triggers the autonomous response control of the synchronous condenser based on the transient response parameters, enabling it to quickly output reactive current to support the grid voltage according to the transient characteristics of the generator terminal voltage. During the transition process, it initiates a coordinated control mechanism for multiple types of reactive resources based on the transition process adjustment parameters. In response to the low-voltage floating state that occurs in the nearby substation after a fault, it adjusts the reactive current output by the synchronous condenser and the switching status of low-voltage capacitors and reactors in the nearby substation in stages. During the steady-state process, it initiates the optimization command of the automatic voltage control system based on the steady-state optimization parameters, resets the capacity of the low-voltage capacitors and reactors called up during the transition process, and restores the dynamic reactive power reserve of the synchronous condenser, thereby completing a complete multi-timescale closed-loop control.

[0021] In one embodiment of the present invention, the resource acquisition module acquires operational status data from the power grid monitoring and data acquisition system, including operational status data of synchronous condensers deployed in hub substations, operational status data of low-voltage capacitors and low-voltage reactors distributed along transmission lines, and operational status data of synchronous generators within the regional power grid. This data serves as the direct input for model construction. The first step in model construction is to establish an electromagnetic transient response sub-model of the synchronous condenser at a millisecond time scale. In specific implementation, the resource acquisition module acquires the stator winding resistance parameters, stator winding reactance parameters, and stator winding time constant parameters of the synchronous condenser; the no-load time constant parameters, forced excitation peak voltage multiple parameters, and response rate parameters of the synchronous condenser's excitation system; and the winding temperature rise limit curve and rotor current limit curve of the synchronous condenser's cooling system. Based on these parameters, the constructed electromagnetic transient response sub-model describes the dynamic relationship between the synchronous condenser's excitation current and output reactive power over time when the grid voltage drops instantaneously. Its core is the simultaneous solution of the synchronous condenser's rotor voltage equation and stator voltage equation.

[0022] The second step in model building is to establish discrete regulation sub-models for low-voltage capacitors and reactors on a second-level time scale. The resource acquisition module collects the rated capacity parameters, rated voltage parameters, average closing delay parameters, average opening delay parameters of the mechanical switching mechanism, and current withstand capability parameters under different harmonics for each group of low-voltage capacitors. Similarly, it collects the rated capacity parameters, rated current parameters, average closing delay parameters, average opening delay parameters of the mechanical switching mechanism, and voltage withstand capability parameters under different harmonics for each group of low-voltage reactors. The discrete regulation sub-model abstracts the low-voltage capacitors and reactors as binary switching elements with fixed capacity and fixed operating delays. Their output state changes stepwise between zero and rated capacity. The model reflects the time lag characteristics between receiving control commands and the actual generation of reactive power.

[0023] The third step in model building is to establish a continuous regulation sub-model for the generator on a minute-level timescale. The resource acquisition module collects the generator's power angle characteristic curve parameters, which reflect the functional relationship between the generator's output active power and power angle. It also collects the proportional-integral-derivative (PID) regulation parameters of the generator's automatic voltage regulator, as well as the upper and lower power limit constraints and power change rate limits of the generator's prime mover. The continuous regulation sub-model describes the process of continuous and smooth regulation of the generator's terminal voltage and reactive power output over a longer timescale under the commands of the automatic voltage control system. The model includes the steady-state gain of the excitation system and the power regulation dynamics of the prime mover.

[0024] In practical implementation, the final step in model construction is to couple the three sub-models mentioned above and introduce the admittance matrix of the power grid topology as an external constraint. The coupling process involves using the output variables of the electromagnetic transient response sub-model as part of the input to the discrete regulation sub-model, and using the output variables of the discrete regulation sub-model as part of the boundary conditions of the continuous regulation sub-model. The admittance matrix of the power grid describes the electrical connection relationships and impedance characteristics between nodes. It is introduced as an external constraint to calculate the node voltage distribution of the entire power grid when the states of synchronous condensers, low-voltage capacitors, low-voltage reactors, and generators at different nodes change. The final multi-timescale model of the multi-type reactive power resource fusion system contains a series of differential-algebraic equations. This model can simultaneously reflect the dynamic characteristics of voltage stability after a large disturbance and the response characteristics of various reactive power resources at different time scales. In practical implementation, the voltage sensitivity matrix of the multi-timescale model of the multi-type reactive power resource fusion system can be expressed as: , Where: vector The matrix represents the sensitivity of each node's voltage to various reactive power resource regulation quantities. The vector represents the nodal admittance matrix of the power grid. This represents the set of state variables, a vector, of the electromagnetic transient response sub-model of the camera. This represents the set of state variables, a vector, for the discrete control sub-model of low-voltage capacitors and low-voltage reactors. This represents the set of state variables for the generator continuous regulation sub-model. (Function) This represents the mapping relationship formed by the coupling of three sub-models and grid constraints. The solution to this mapping relationship generates a multi-timescale model of a multi-type reactive power resource fusion system.

[0025] In one embodiment of the present invention, see [reference] Figure 2 The fusion modeling module analyzes the constructed multi-timescale models of the multi-type reactive power resource fusion system. The electromagnetic transient response sub-model of the synchronous condenser included in the model has a millisecond-level response delay time constant, extracted from the no-load time constant and stator winding time constant of the synchronous condenser excitation system. The discrete regulation sub-models of low-voltage capacitors and low-voltage reactors included in the model have second-level operating cycles, determined by the average closing delay parameter and average opening delay parameter of the low-voltage capacitor switching mechanism. The generator continuous regulation sub-model included in the model is associated with the automatic voltage control system, whose regulation cycle is on the order of minutes, extracted from the optimization calculation cycle and command issuance cycle of the automatic voltage control system.

[0026] The scan period of the millisecond-level control timing is set to a fixed value. The millisecond-level control timing is only associated with the excitation voltage setpoint of the synchronous condenser, and its control logic is designed to capture the initial voltage drop waveform after a fault occurs. In practice, the millisecond-level control timing executes once per scan cycle. Its control algorithm continuously reads the real-time voltage sample value of the synchronous condenser's access point and compares it with the sample value of the previous cycle. Once a sharp drop in voltage is detected within several consecutive cycles, the control algorithm determines that a transient fault has occurred and prepares to issue a strong excitation command to the synchronous condenser. The decision-making and execution process of the millisecond-level control timing is completely independent of the second-level and minute-level control, and its goal is to initiate the autonomous response of the synchronous condenser within the first cycle after a fault occurs.

[0027] The scan period of the second-level control timing is set to be longer than that of the millisecond-level control timing. In some embodiments, the scan period of the second-level control timing is set to 500 milliseconds. The second-level control timing is associated with the reactive power output setpoint of the synchronous condenser and the switching status words of the low-voltage capacitors and low-voltage reactors. In specific implementations, the input information of the second-level control timing includes the voltage recovery curve of the power grid after millisecond-level control intervention, the real-time voltage values ​​of each node, and the current switching positions of the low-voltage capacitors and low-voltage reactors. Based on this information, the control logic of the second-level control timing calculates whether it is necessary to fine-tune the reactive power output of the synchronous condenser or whether it is necessary to perform switching operations on the low-voltage capacitors and low-voltage reactors to eliminate the low-voltage floating state after a fault. The instructions issued by the second-level control timing are discrete switching instructions or setpoint adjustment instructions.

[0028] The scan cycle of the minute-level control sequence is set to be longer than that of the second-level control sequence. The minute-level control sequence is associated with the global voltage reference value and reactive power optimization command queue of the automatic voltage control system. In specific implementation, at the start of each scan cycle, the minute-level control sequence obtains the latest global voltage reference value from the grid energy management system. This reference value is set by the dispatcher or provided by a higher-level optimization algorithm. Simultaneously, the minute-level control sequence reads the final switching status of low-voltage capacitors and low-voltage reactors recorded by the second-level control process. The core of the minute-level control sequence is the optimization algorithm of the automatic voltage control system. This algorithm, with the objectives of minimizing overall network losses and minimizing voltage over-limit risks, calculates and generates a reactive power optimization command queue for slow-regulating equipment such as generators and transformer tap changes.

[0029] In implementation, the configured millisecond-level, second-level, and minute-level control timing sequences are embedded into a unified scheduling engine to ensure serial execution of instructions. The unified scheduling engine is a software process responsible for managing the generation, queuing, and issuance of control instructions across the three timescales. Millisecond-level control timing sequences have the highest execution priority and are scheduled for execution immediately after generation. Instructions for second-level control timing sequences must wait for the current millisecond-level control timing instruction cycle to complete before being scheduled. Minute-level control timing sequences have the lowest priority and are scheduled only during idle periods when the current second-level control timing sequence has no instructions executing. The scheduling engine internally maintains an instruction timestamp queue, marking the timescale and generation time of each issued instruction, thus logically achieving conflict-free serial execution of millisecond-level, second-level, and minute-level control instructions along the timeline.

[0030] In practical implementation, the autonomous response control of the synchronous condenser is triggered based on transient response parameters. The implementation details are as follows: The instantaneous value of the terminal voltage at the synchronous condenser's access point is monitored in real time by a high-speed data acquisition unit, which samples the voltage waveform at a rate of at least 10,000 points per second. The per-unit deviation of the instantaneous voltage value at the computer terminal of the fusion modeling module relative to the rated voltage is calculated in real time within each control cycle. When the calculated per-unit deviation is lower than a preset voltage collapse threshold, the control logic activates the built-in forced excitation control module of the synchronous condenser. The voltage collapse threshold is typically set to 0.8 to 0.85 per-unit. After activation, the forced excitation control module immediately sends a command exceeding conventional limits to the synchronous condenser's excitation regulator. This command removes conventional limitations such as the upper limit of the excitation current and the limit of the excitation voltage rise rate of the synchronous condenser's excitation system. After the command is executed, the excitation system forcibly increases the excitation current of the synchronous condenser to its peak value. The peak excitation current is generally 1.5 to 2 times the rated excitation current and is maintained for a predetermined time window. This time window is determined by the thermal capacity of the synchronous condenser rotor winding and is usually several seconds. During this forced excitation process, the synchronous condenser injects maximum inductive reactive current into the grid. This current value can be estimated using the formula: , in: This indicates the maximum inductive reactive power that the synchronous condenser can output during the strong excitation period. It is the potential coefficient of the phase converter, which is determined by the stator winding parameters in the electromagnetic transient response sub-model of the phase converter. This represents the peak excitation voltage reached during the forced excitation period. This indicates the no-load excitation voltage of the camera before the fault occurred. This represents the peak excitation current reached during the forced excitation period. Throughout the entire autonomous response of the synchronous condenser, the coordination execution module will block any reactive power regulation commands issued by the second-level control timing. The blocking logic ensures that the forced excitation process is not disturbed by other slow regulation until the instantaneous value of the generator terminal voltage recovers to above the set safety threshold value, which is usually set to 0.9 per unit. At this point, the autonomous response process ends.

[0031] In one embodiment of the present invention, after the autonomous response control of the synchronous condenser ends, i.e., after the transient process phase ends, the coordination execution module reads the voltage recovery curves of each node in the power grid at the current moment, provided by the power grid wide-area measurement system. The coordination execution module analyzes the voltage recovery curves and identifies a list of nearby substations in a low-voltage floating state. It can be understood that a low-voltage floating state refers to a situation where the node voltage does not return to the normal range after the fault is cleared, but remains at a low level below the rated value for a long time, for example, fluctuating between 0.90 and 0.95 per unit. In specific implementation, the coordination execution module determines that substations with voltages below 0.95 per unit for more than 1 second are in a low-voltage floating state and adds them to the list of nearby substations to be processed.

[0032] In practical implementation, based on the reactive power demand gap calculation rules in the transition process adjustment parameters, the required reactive power compensation increment for each near-field substation in a low-voltage floating state is calculated. The calculation of the reactive power demand gap is based on the node voltage sensitivity matrix to injected reactive power and the deviation between the target voltage and the current voltage. In some embodiments, for each substation i in the near-field substation list, its required reactive power compensation increment is... Calculated using the following formula: , in: This represents the target voltage value for substation i, typically set to 1.0 per unit. This represents the current actual voltage measurement value of substation i. This represents the self-admittance voltage sensitivity coefficient of substation i calculated in the multi-timescale model of the multi-type reactive power resource fusion system. Its physical meaning is the change in voltage at substation i when a unit of reactive power is injected. After calculating the reactive power compensation increment for all low-voltage floating substations, the coordination execution module prioritizes adjusting the reactive power output setpoint of the synchronous condenser. The coordination execution module sends a new reactive power output setpoint instruction to the synchronous condenser, causing its reactive power output to bear the majority share of the calculated total reactive power compensation increment, for example, 70% of the total increment. While adjusting the reactive power output of the synchronous condenser, the coordination execution module records the current reactive power margin of the synchronous condenser, defined as the difference between its current reactive power output and its maximum allowable reactive power output. If the calculation finds that the reactive power margin of the synchronous condenser is insufficient to fill the remaining reactive power compensation increment, the coordination execution module generates an instruction to connect low-voltage capacitors or an instruction to disconnect low-voltage reactors. It is understandable that the discrete capacity of low-voltage capacitors and low-voltage reactors is used to make up the difference. That is, when it is necessary to increase capacitive reactive power, an instruction is issued to connect one or more sets of low-voltage capacitors; when it is necessary to reduce capacitive reactive power, an instruction is issued to disconnect one or more sets of low-voltage reactors. The coordination execution module sorts the list of nearby substations according to the urgency of voltage restoration, with substations having lower voltage values ​​and slower voltage restoration speeds ranked higher. The coordination execution module then performs reactive power allocation and equipment adjustment steps on the ranked substations in sequence until all low-voltage floating states are eliminated, that is, the voltage of all relevant substations is restored to above 0.98 per-unit value.

[0033] In practical implementation, to address the low-voltage floating state that occurs in nearby substations after a fault, the reactive current output of the synchronous condenser and the switching status of low-voltage capacitors and reactors within the nearby substation are adjusted in stages. The first stage of the staged adjustment is defined as the emergency support stage, which is only executed if the synchronous condenser has not reached its thermal stability limit. In the emergency support stage, the coordination execution module rapidly increases the reactive power output of the synchronous condenser to its maximum allowable value, which is determined by the real-time monitored rotor and stator temperatures. The purpose of the emergency support stage is to utilize the rapid and continuous adjustment capability of the synchronous condenser to provide maximum reactive power support within seconds, quickly curbing the continued voltage drop trend.

[0034] The second round of phased regulation is defined as the refined compensation round. After the first round of emergency support is completed, the coordination execution module reassesses the voltage levels of each node in the power grid. If the grid voltage still does not reach the preset normal voltage range, the coordination execution module begins the second round of refined compensation. In the refined compensation round, the coordination execution module calculates the switching combinations of low-voltage capacitors and low-voltage reactors. Based on the current power factor level of the power grid, the coordination execution module determines whether it is necessary to connect low-voltage capacitors to increase capacitive reactive power or to connect low-voltage reactors to offset excess capacitive reactive power. In some embodiments, when the node voltage is low and the power factor is high, it is determined that low-voltage capacitors need to be connected; when the node voltage is low but the power factor is very low or even negative, it is determined that there may be excess capacitive reactive power, and low-voltage reactors need to be connected to offset it.

[0035] In practice, the coordination and execution module generates specific switching action commands to control the circuit breaker closing of low-voltage capacitors or low-voltage reactors. The module sends remote closing or opening commands to the designated low-voltage capacitor or reactor switches in the substation. After each switching action command is executed, the module waits for a complete power frequency cycle (20 milliseconds) to observe the voltage feedback, allowing the transient process caused by the switching action to subside and accurately measure the new steady-state voltage value. Based on the new voltage measurement, the module recalculates whether there is still a reactive power deficit and determines whether the next group of low-voltage capacitors or reactors needs to be switched. The module iteratively executes the judgment and action of the second round of refined compensation until the grid voltage stabilizes within the preset normal fluctuation range, for example, all relevant bus voltages are maintained between 0.98 and 1.02 per unit, and voltage fluctuations are less than 0.5% for five consecutive measurement cycles.

[0036] See Figure 3This is a graph showing the reactive power output and voltage changes of the synchronous condenser during phased regulation. It illustrates the dynamic relationship between the reactive power output of the synchronous condenser and the recovery of grid voltage during phased regulation in multi-timescale reactive resource coordinated control, representing a typical operating curve for the transient phase. In the first phase, the reactive power output of the synchronous condenser rapidly climbs from 80 MVar to approximately 100 MVar, approaching full load output within 5 seconds, demonstrating its rapid response and strong excitation support transient characteristics. The core objective at this stage is to quickly curb voltage drops, buying time for subsequent transient regulation. In the second phase, the reactive power output of the synchronous condenser gradually increases from 95 MVar to 100 MVar and remains stable, indicating that after emergency support, the synchronous condenser enters a continuous reactive power support state, cooperating with low-voltage capacitors / reactors to complete refined compensation. The voltage recovery voltage gradually increases from 0.92 per unit value, reaching the voltage recovery target of 0.98 per unit value in about 12.5 seconds, and finally stabilizes in the range of 0.99~1.00 per unit value, which meets the control requirement of "maintaining the voltage in the range of 0.98~1.02 per unit value".

[0037] In one embodiment of the present invention, after all adjustment operations during the transition phase are completed, i.e., the grid voltage has recovered to the normal fluctuation range and remained stable for more than one minute, the coordination execution module freezes the current reactive power resource status snapshot. The reactive power resource status snapshot includes the real-time reactive power output value of the synchronous condenser, the number of low-voltage capacitor banks connected, and the number of low-voltage reactor banks disconnected. The coordination execution module packages the reactive power resource status snapshot, the current grid topology, and the real-time load data of each node and sends them to the automatic voltage control system. In a specific implementation, the coordination execution module switches the automatic voltage control system to optimization mode. In optimization mode, the automatic voltage control system reads the economic dispatch weight factor from the steady-state optimization parameters. The economic dispatch weight factor is a coefficient used to weigh the relative importance of the goal of minimizing network losses and the goal of maximizing the dynamic reactive power reserve of the synchronous condenser. The automatic voltage control system constructs the adjustment cost function for low-voltage capacitors and low-voltage reactors with the dual objectives of minimizing the network losses and maximizing the dynamic reactive power reserve of the synchronous condenser. The automatic voltage control system solves the adjustment cost function to obtain a set of optimal switching state combinations that allow the synchronous condenser to exit the auxiliary support state and return to the economic operating range. In practical implementation, the automatic voltage control system issues the optimal switching state combination to the coordination execution module in the form of a command sequence. The coordination execution module parses the command sequence and generates specific control commands to disconnect over-energized low-voltage capacitors or re-energize over-deactivated low-voltage reactors, thereby releasing the reserve capacity of the synchronous condenser. It can be understood that the solution process for the optimal switching state combination is an optimization calculation based on linear programming or mixed-integer programming. Its goal is to find a set of switching states for low-voltage capacitors and low-voltage reactors that minimizes the overall cost comprised of network loss cost and the value of the synchronous condenser's reserve capacity, while satisfying all node voltage constraints. In some embodiments, the adjustment cost function can be expressed as: , in: This represents the overall cost to be minimized. It is the network loss economic coefficient in the steady-state optimization parameters, which is related to the generation cost and electricity price. This represents the predicted total active power loss of the entire power grid under the current power grid operating conditions. It is the dynamic reactive power reserve value coefficient in the steady-state optimization parameters, reflecting the system's willingness to maintain the backup capacity of the synchronous condenser in order to cope with potential future failures. This represents the dynamic reactive power reserve available to the synchronous condenser under the current switching state. The automatic voltage control system is subject to a series of constraints during the solution process, including upper and lower limit constraints on node voltages, integer constraints on the number of low-voltage capacitors and reactors that can be switched, and upper and lower limit constraints on the reactive power output of the synchronous condenser.

[0038] In practical implementation, the capacity of low-voltage capacitors and low-voltage reactors called up during the transition phase is reset, and the dynamic reactive power reserve of the synchronous condenser is restored. The implementation process is as follows: The coordination execution module receives the optimal switching state combination command from the automatic voltage control system, compares the optimal switching state combination command with the current actual switching state, and identifies low-voltage capacitors and low-voltage reactors with discrepancies. The coordination execution module sends trip commands only to low-voltage capacitors with discrepancies, or close commands only to low-voltage reactors with discrepancies, to avoid unnecessary switching actions. After each successful execution of a low-voltage capacitor or low-voltage reactor state change operation, the coordination execution module immediately reads the synchronous condenser's terminal voltage measurement value and reactive power load measurement value through the data acquisition system. Based on the latest grid voltage level, the coordination execution module linearly lowers the synchronous condenser's excitation current setpoint. In practice, the linear reduction process involves the coordinated execution module decreasing the excitation current setpoint of the synchronous condenser by a fixed step size in each control cycle. This step size is dynamically calculated based on the difference between the current reactive load and the target reactive load of the synchronous condenser, allowing it to gradually unload the excess reactive load it bears during the transition. During the adjustment process, the coordinated execution module continuously monitors the rotor current and stator temperature measurements of the synchronous condenser to ensure that no equipment protection limits are triggered while restoring the dynamic reactive power reserve. It can be understood that the rotor overcurrent protection and stator overheat protection setpoints of the synchronous condenser remain effective throughout the entire process. Once the monitored values ​​approach the protection limits, the coordinated execution module will pause the reduction of the excitation current setpoint until the measured values ​​fall back to a safe range.

[0039] In some embodiments, the optimization results during the steady-state process and the specific equipment status data involved in the subsequent reset operation can be recorded as shown in Table 1. Referring to Table 1, the changes in the switching status of relevant reactive power resources and the changes in key electrical quantities before and after the execution of the optimization command are shown.

[0040] Table 1: Examples of Equipment Status and Electrical Quantity Changes During Steady-State Optimization and Capacity Reset Processes Device / Parameters State before optimization and reset operation Optimal switch state combination instruction Post-optimization and reset status No. 1 camera condenser's reactive power output +250 No direct switch command +150 No. 2 synchronous condenser reactive power output +180 No direct switch command +100 Number of low-voltage capacitor banks connected in substation A 3 groups Two groups were removed Group 1 Number of low-voltage capacitor banks connected in substation B 2 groups 1 group of resections Group 1 Number of low-voltage reactors removed from substation C Group 1 Invest 1 set 0 groups Total network loss 8.5 Calculate the optimal value 7.2 Total dynamic reactive power reserve 200 Calculate the optimal value 380 See Figure 4 This is a trend chart of network loss and dynamic reactive power reserve optimization, reflecting the changing trends of total active power loss and total dynamic reactive power reserve with the number of iterations during the multi-timescale reactive power resource optimization process. Total active power loss decreases linearly with increasing iteration steps, reflecting improved grid transmission efficiency and reduced active power loss after optimization. Total dynamic reactive power reserve increases linearly with increasing iteration steps, reflecting the recovery of synchronous condenser reactive power reserve capacity and enhanced system voltage support capability. This visually verifies the synergistic achievement of the two objectives of steady-state optimization, with network loss reduction and reactive power reserve improvement occurring simultaneously. During the rapid optimization period of 0-5 steps, both the reduction in network loss and the increase in reactive power reserve are significant, and the algorithm quickly converges to a feasible solution. During the stable optimization period of 5-20 steps, the rate of change of indicators slows down, and the algorithm gradually approaches the global optimum. This curve can be used to evaluate the convergence speed of the optimization algorithm, determine the optimal iteration termination step, and provide a quantitative basis for actual grid reactive power resource scheduling.

[0041] In one embodiment of the invention, when switching from the transient process stage to the transition process stage, the control coordination module transmits the peak reactive power output value and duration recorded by the synchronous condenser during its autonomous response to the coordination control mechanism of the transition process stage. Specifically, the peak reactive power output value refers to the measured value of the maximum inductive reactive power actually output by the synchronous condenser during forced excitation, and the duration refers to the time it takes for the terminal voltage to recover from below the voltage collapse threshold to above the safety threshold. The control coordination module uses these data as the initial boundary conditions for the transition process adjustment parameters. After receiving the peak reactive power output value and duration, the coordination control mechanism of the transition process stage uses this information to initialize the estimation of the reactive power demand gap. For example, a large amount of reactive power released by the synchronous condenser during the transient stage means that the initial reactive power deficit of the nearby power grid may have been partially compensated, and the reactive power compensation increment calculation during the transition process stage will deduct this compensated amount from the total demand. The peak reactive power output value is also used to assess the remaining reactive power regulation capacity of the synchronous condenser under the current operating conditions, serving as the basis for the coordination control mechanism of the transition process stage to allocate the reactive power output of the synchronous condenser.

[0042] In practice, during the transition from the transient phase to the steady-state phase, the control coordination module packages and sends the final switching status of low-voltage capacitors and reactors, along with the final voltage distribution data of the power grid, to the automatic voltage control system. The final switching status of low-voltage capacitors and reactors includes whether each group of low-voltage capacitors and reactors is in the engaged or disengaged position at the end of the transient phase. The final voltage distribution data refers to the steady-state voltage values ​​of all key nodes obtained from the power grid wide-area measurement system after the final equipment adjustment action is completed and the system has stabilized following the transient phase. These final switching statuses of low-voltage capacitors and reactors, along with the final voltage distribution data of the power grid, are used as input variables for steady-state optimization parameters. Based on these input variables, and in conjunction with the current power grid topology and load forecasts, the automatic voltage control system performs steady-state optimization calculations to determine whether adjustments to the states of low-voltage capacitors and reactors are needed to further optimize economic operation.

[0043] In practical implementation, before the steady-state process ends and the next monitoring cycle begins, the control coordination module generates a control closed-loop report containing key indicators across three time scales. The control closed-loop report records the response time of the synchronous condenser during the current control event. Response time refers to the time interval from when the voltage at the synchronous condenser's terminals drops below the trigger threshold to when the synchronous condenser's forced excitation action ends and the excitation current begins to decline. The control closed-loop report records the total number of actions of low-voltage capacitors and low-voltage reactors during the transient process and steady-state optimization reset process. The number of actions refers to the sum of the number of opening and closing operations for each group of low-voltage capacitors and low-voltage reactors. The control closed-loop report records the steady-state deviation value of the entire network voltage. The steady-state deviation value is the root mean square value of the difference between the voltage at each node and the rated voltage after the optimization reset operation. The control coordination module writes the data from the control closed-loop report back to the multi-time-scale model of the multi-type reactive power resource fusion system to correct the lag parameters in the model. In practical implementation, the correction process mainly targets the parameters in the model representing equipment response delay and control system delay. For example, model parameters can be calibrated by comparing the actual response time of the synchronous condenser recorded in the control closed-loop report with the preset synchronous condenser response delay time constant in the model. By analyzing the correspondence between the number of actions of low-voltage capacitors and low-voltage reactors and the voltage recovery curve, the mechanical switching delay parameters in the discrete control sub-model can be fine-tuned. These corrections enable the multi-timescale model of the multi-type reactive power resource fusion system to adapt to the slow drift of grid operating conditions, such as characteristic changes caused by equipment aging or electrical characteristic changes caused by minor changes in network structure. The control coordination module can use parameter identification algorithms such as recursive least squares to complete the online correction of the model's lag parameters. In some embodiments, the update formula for correcting the time constant of the discrete control sub-model can be expressed as: , in: This represents the equivalent time constant of the switching operation of the updated low-voltage capacitor or low-voltage reactor. This represents the equivalent time constant of the original throwing and cutting action in the model. It is a preset learning rate coefficient used to control the magnitude of parameter updates. It is the actual average time from receiving a command to the completion of a state change for a low-voltage capacitor or low-voltage reactor, which is statistically obtained from the control closed-loop report. It is based on the original parameters of the model. And the predicted action time under current operating conditions. By continuously comparing and correcting the actual action time with the model's predicted time, the model can more accurately reflect the true dynamic characteristics of the equipment.

[0044] In practice, the emergency control module operates as follows: When the power grid monitoring system detects an alarm signal indicating a commutation failure at a DC transmission system inverter station, the emergency control module immediately interrupts any ongoing control flow at any time scale. The emergency control module forcibly switches to the high-voltage, high-capacity reactive power support mode for commutation failure. In this mode, the emergency control module ignores steady-state optimization parameters and economic dispatch weighting factors. The emergency control module directly locks the reactive power output of the synchronous condenser to a preset maximum output value, which is typically set as the upper limit of the synchronous condenser's sustainable safe output under forced excitation, a value higher than its maximum output during normal operation. Simultaneously, the emergency control module sends instructions to simultaneously activate multiple sets of low-voltage capacitors in the vicinity of the DC transmission system. Utilizing the instantaneous high-capacity characteristics of the low-voltage capacitors to compensate for the reactive power deficit caused by the commutation failure, the instantaneous activation of the low-voltage capacitors can provide a large amount of capacitive reactive power within several cycles. The emergency control module maintains the high-voltage, high-capacity reactive power support mode until it receives a power restoration command from the DC transmission system. Upon receiving a power restoration command from the DC transmission system, the emergency control module sequentially disconnects low-voltage capacitors and gradually reduces the reactive power output of the synchronous condenser according to the normal timing sequence. The disconnection process is smooth; the emergency control module controls the low-voltage capacitors to disconnect in groups one by one, observing voltage stability after each group disconnects, while linearly reducing the reactive power output setpoint of the synchronous condenser. After all low-voltage capacitors have disconnected and the reactive power output of the synchronous condenser has dropped to the normal operating range, the emergency control module returns control to the regular multi-timescale control process, and the system returns to the monitoring and regulation state dominated by the coordination and execution module.

[0045] See Figure 5This is a bar chart comparing the parameter corrections of the reactive power resource model, visually demonstrating the changes in the values ​​of four key time delay parameters before and after the correction, reflecting the model's adaptation to grid operating conditions. All parameters are initialized to 1.0 for easy comparison of the correction magnitude. The 5% reduction in synchronous condenser response delay reflects the model's optimization of the fast response characteristics of synchronous condensers, better meeting the requirements of millisecond-level transient control. The slight increase in capacitor delay and slight decrease in reactor delay reflect a refined differentiation of the discrete adjustment characteristics of different reactive power equipment. This differentiated correction of capacitor / reactor delay provides more precise timing constraints for the round-by-round adjustment of second-level coordinated control. The slight 1% increase in control system delay reflects a conservative correction to the overall control closed-loop delay, improving model robustness. This differentiated correction strategy can better match the response characteristics of different equipment under a multi-timescale control framework, improving the accuracy of reactive power resource coordinated control.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications 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 protection scope of the present invention.

Claims

1. A multi-timescale reactive power resource fusion and coordination control system, characterized in that, include: The resource acquisition module acquires the operating status data of synchronous condensers, low-voltage capacitors, low-voltage reactors and generators deployed in the power grid, and constructs a multi-timescale model of a multi-type reactive power resource fusion system with the synchronous condensers as the core, including transient response parameters, transient process adjustment parameters and steady-state optimization parameters. The fusion modeling module, based on the multi-timescale model of the multi-type reactive resource fusion system, configures control timing sequences at the millisecond, second, and minute levels respectively, forming a full-time chain control framework covering the transient process stage, the transition process stage, and the steady-state process stage. The coordinated execution module, during the transient process phase, triggers the autonomous response control of the synchronous condenser based on the transient response parameters, enabling it to rapidly output reactive current to support the grid voltage according to the transient characteristics of the generator terminal voltage. During the transition process phase, it initiates a coordinated control mechanism for multiple types of reactive resources based on the transition process adjustment parameters. In response to the low-voltage floating state that occurs in the nearby substation after a fault, it adjusts the reactive current output by the synchronous condenser and the switching status of the low-voltage capacitors and low-voltage reactors in the nearby substation in stages. During the steady-state phase, it initiates the optimization command of the automatic voltage control system based on the steady-state optimization parameters, resets the capacity of the low-voltage capacitors and low-voltage reactors called up during the transition process phase, and restores the dynamic reactive power reserve of the synchronous condenser, completing a complete multi-timescale closed-loop control.

2. The multi-timescale reactive power resource fusion and coordination control system according to claim 1, characterized in that, Constructing a multi-time-scale model for a multi-type reactive power resource fusion system, including: Collect the stator winding parameters, excitation system response rate, and cooling system limitation curve of the synchronous condenser, and establish an electromagnetic transient response sub-model of the synchronous condenser on a millisecond time scale. The rated capacity, mechanical switching delay, and harmonic tolerance of the low-voltage capacitor and the low-voltage reactor are collected to establish a discrete adjustment sub-model of the low-voltage capacitor and the low-voltage reactor on a second-level time scale. Collect the generator's power angle characteristic curve, excitation regulator parameters, and prime mover power constraints to establish a continuous regulation sub-model of the generator on a minute-level time scale; The electromagnetic transient response sub-model, the discrete regulation sub-model, and the continuous regulation sub-model are coupled together, and the admittance matrix of the power grid topology is introduced as an external constraint to generate a multi-timescale model of the multi-type reactive power resource fusion system that simultaneously reflects the dynamic characteristics and response characteristics of the power grid voltage stability.

3. The multi-timescale reactive power resource fusion and coordination control system according to claim 2, characterized in that, Based on the multi-time-scale model of the multi-type reactive power resource fusion system, control timing sequences at the millisecond, second, and minute levels are configured respectively, including: The time constants of each sub-model in the multi-time-scale model of the multi-type reactive power resource fusion system are analyzed, and the response delay of the synchronous condenser, the action cycle of the low-voltage capacitor switching mechanism, and the adjustment cycle of the automatic voltage control system are extracted. The scan period of the millisecond-level control timing is set to a fixed value. The millisecond-level control timing is only associated with the excitation voltage setpoint of the synchronous condenser and is used to capture the initial voltage drop waveform after a fault occurs. The scanning period of the second-level control timing is set to be greater than that of the millisecond-level control timing. The second-level control timing is associated with the reactive power output setting value of the synchronous condenser and the switching status words of the low-voltage capacitor and the low-voltage reactor. The scan period of the minute-level control timing is set to be greater than that of the second-level control timing, and the minute-level control timing is associated with the global voltage reference value and the reactive power optimization instruction queue of the automatic voltage control system. The configured millisecond-level control timing, second-level control timing, and minute-level control timing are embedded into the unified scheduling engine to ensure that control commands at the three time scales are executed serially without conflict on the time axis.

4. The multi-timescale reactive power resource fusion and coordination control system according to claim 3, characterized in that, During the transient process phase, the autonomous response control of the synchronous condenser is triggered based on the transient response parameters, including: Real-time monitoring of the instantaneous terminal voltage value at the synchronous condenser access point, and calculation of the per-unit deviation of the instantaneous terminal voltage value relative to the rated voltage; When the per-unit deviation is lower than the preset voltage collapse threshold, the built-in strong excitation control module of the synchronous condenser is activated to release the normal restrictions of the synchronous condenser excitation system. The excitation current of the synchronous condenser is forcibly increased to a maximum value and maintained for a predetermined time window, thereby forcing the synchronous condenser to inject maximum inductive reactive current into the power grid. During the autonomous response of the synchronous condenser, any reactive power adjustment commands issued by the second-level control timing are blocked until the instantaneous value of the generator terminal voltage recovers to above the set safety threshold value.

5. The multi-timescale reactive power resource fusion and coordination control system according to claim 4, characterized in that, During the transition phase, a coordinated control mechanism for multiple types of reactive power resources is initiated based on the transition phase adjustment parameters, including: After the transient process ends, the voltage recovery curves of each node in the power grid at the current moment are read, and the list of nearby substations in the low voltage floating state is identified. Based on the reactive power demand gap calculation rules in the transition process adjustment parameters, the reactive power compensation increment required for each near-area substation in the low-voltage floating state is calculated respectively. Prioritize adjusting the reactive power output setting value of the synchronous condenser to make it bear the main share of the reactive power compensation increment, and record the current reactive power margin of the synchronous condenser; If the reactive power margin of the synchronous condenser is insufficient to fill the remaining reactive power compensation increment, an input command for the low-voltage capacitor or an output command for the low-voltage reactor is generated, and the discrete capacity of the low-voltage capacitor and the low-voltage reactor is used to make up the difference. The list of nearby substations is sorted according to the urgency of voltage restoration, and reactive power allocation and equipment adjustment steps are performed sequentially until all the low voltage floating states are eliminated.

6. The multi-timescale reactive power resource fusion and coordination control system according to claim 5, characterized in that, To address the low-voltage floating state that occurs in nearby substations after a fault, the reactive current output by the synchronous condenser and the switching status of the low-voltage capacitors and reactors within the nearby substation are adjusted in stages, including: The first round of the phased adjustment is defined as the emergency support round, in which the reactive power output of the synchronous condenser is increased to the maximum allowable value only when the synchronous condenser has not reached its thermal stability limit. The second round of the phased adjustment is defined as the refined compensation round. If the grid voltage still does not meet the standard after the first round is completed, the switching combination of the low-voltage capacitor and the low-voltage reactor will be calculated. Based on the current power factor level of the power grid, determine whether it is necessary to put the low-voltage capacitor into operation to increase capacitive reactive power, or to put the low-voltage reactor into operation to offset the excess capacitive reactive power. Generate specific switching action commands to control the circuit breaker of the low-voltage capacitor or the low-voltage reactor to close, and wait for a complete power frequency cycle after each action to observe the voltage feedback. The judgment and action of the second round are executed repeatedly until the grid voltage stabilizes within the preset normal fluctuation range.

7. The multi-timescale reactive power resource fusion and coordination control system according to claim 6, characterized in that, During the steady-state process, optimization commands for the automatic voltage control system are initiated based on the aforementioned steady-state optimization parameters, including: After all adjustment operations are completed during the transition phase, the current reactive power resource status snapshot is frozen. The status snapshot includes the real-time reactive power output of the synchronous condenser, the number of low-voltage capacitor banks connected, and the number of low-voltage reactor banks disconnected. Switch the automatic voltage control system to optimization mode and read the economic dispatch weight factor in the steady-state optimization parameters; With minimizing the network loss and maximizing the dynamic reactive power reserve of the synchronous condenser as dual objectives, the adjustment cost function of the low-voltage capacitor and the low-voltage reactor is constructed. Solving the adjustment cost function yields a set of optimal switching state combinations that allow the synchronous condenser to exit the auxiliary support state and return to the economic operating range; The control command corresponding to the optimal switching state combination is issued to disconnect the over-energized low-voltage capacitor or re-energize the over-deactivated low-voltage reactor, thereby releasing the standby capacity of the synchronous condenser.

8. The multi-timescale reactive power resource fusion and coordination control system according to claim 7, characterized in that, The capacity of the low-voltage capacitors and low-voltage reactors invoked during the transition process is reset, and the dynamic reactive power reserve of the synchronous condenser is restored, including: Check the differences between the optimal switching state combination issued by the automatic voltage control system and the current actual switching state; A trip command is sent only to the low-voltage capacitor with the discrepancy, or a closing command is sent only to the low-voltage reactor with the discrepancy, in order to avoid unnecessary switching operations. After each successful state change operation of the low-voltage capacitor or the low-voltage reactor, the terminal voltage and reactive load data of the synchronous condenser are immediately read. Based on the latest grid voltage level, the excitation current setting value of the synchronous condenser is linearly reduced so that it gradually unloads the excess reactive load it bears during the transition process; The rotor current and stator temperature of the synchronous condenser are continuously monitored to ensure that no equipment protection limits are triggered during the process of restoring the dynamic reactive power reserve.

9. The multi-timescale reactive power resource fusion and coordination control system according to claim 8, characterized in that, Also includes: The control and coordination module, when switching from the transient process stage to the transition process stage, transmits the peak reactive power output value and duration recorded by the synchronous condenser during the autonomous response period to the coordination control mechanism of the transition process stage as the initial boundary conditions for the transition process adjustment parameters. When switching from the transition process stage to the steady-state process stage, the final switching state of the low-voltage capacitor and the low-voltage reactor, as well as the final voltage distribution data of the power grid, are packaged and sent to the automatic voltage control system as input variables for the steady-state optimization parameters. Before the steady-state process ends and the next monitoring cycle begins, a control closed-loop report containing key indicators on three time scales is generated. The control closed-loop report records the response time of the synchronous condenser, the number of times the low-voltage capacitor and the low-voltage reactor operate, and the steady-state deviation of the entire network voltage. The data in the control closed-loop report is written back to the multi-time-scale model of the multi-type reactive power resource fusion system to correct the lag parameters in the model in order to adapt to the slow drift of the power grid operating conditions.

10. The multi-timescale reactive power resource fusion and coordination control system according to claim 9, characterized in that, Also includes: When the emergency control module detects an alarm signal of commutation failure at the inverter station of the DC transmission system in the power grid, it immediately interrupts the current control process and forcibly switches to the high-voltage, high-capacity reactive power support mode for commutation failure. In the high-voltage, high-capacity reactive power support mode, the steady-state optimization parameters and economic dispatch weight factors are ignored, and the reactive power output of the synchronous condenser is directly locked to the preset maximum output value. At the same time, instructions are sent to multiple sets of low-voltage capacitors in the vicinity of the DC transmission system to be put into operation simultaneously, so as to make up for the reactive power deficit caused by commutation failure by utilizing the instantaneous large capacity characteristics of the low-voltage capacitors. The high-voltage, high-capacity reactive power support mode is maintained until the power recovery command of the DC transmission system is issued. Then, the low-voltage capacitors are withdrawn in sequence according to the normal timing, and the reactive power output of the synchronous condenser is gradually reduced, smoothly transitioning back to the conventional multi-timescale control process.

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