A transient voltage stabilization control method that coordinates generator excitation and reactive power compensation

Abstract

This invention discloses a transient voltage stability control method that coordinates generator excitation and reactive power compensation. In the transient voltage stability control of the receiving-end power grid, reactive power optimization based on indices that cannot be quantitatively evaluated for transient voltage stability margin is insufficient to effectively improve the system's transient voltage stability. The technical solution adopted in this invention is as follows: First, transient voltage data of the receiving-end power grid is acquired using a wide-area synchronous phasor measurement device, transient voltage evaluation indices are calculated, and candidate reactive power compensation nodes and candidate control plants are selected accordingly. Then, compensation sensitivity and parameter adjustment sensitivity are calculated, and the final reactive power compensation nodes and parameter adjustment control plants are determined. Constraint equations and objective functions for the transient voltage optimization control problem are constructed. Finally, the particle swarm optimization algorithm is used to solve for the reactive power compensation capacity change and the parameter adjustment amplitude of each power plant. This invention can provide an optimized solution for the transient voltage control problem of the receiving-end power grid, contributing to more effective and stable voltage control of the power system.

Description

Technical Field

[0001] This invention relates to the field of power system operation control, and in particular to a transient voltage stabilization control method that coordinates generator excitation and reactive power compensation. Background Technology

[0002] Given the inverse distribution of energy resources and load demand in my country, the scale of long-distance, large-capacity power transmission projects, exemplified by ultra-high-voltage direct current (UHVDC) projects, continues to grow. However, for the receiving-end system, with the increasing electricity load, power from outside the region has replaced a large number of local generating units, resulting in a shortage of dynamic reactive power sources and weak voltage support capabilities. On the other hand, the replacement of generating units in the receiving-end grid also reduces the equivalent inertia of the receiving-end system, significantly weakening its ability to withstand disturbances. When a serious fault occurs in the receiving-end power system, local power sources cannot meet the required reactive power, and the shortfall in reactive power is difficult to transmit over long distances via transmission lines, leading to transient voltage instability in the receiving-end grid.

[0003] In terms of transient voltage stability assessment methods, engineering standards widely use an instability criterion based on transient voltage being below a certain threshold for a certain period of time. However, this criterion cannot quantify the degree of transient voltage stability and is difficult to apply effectively to transient voltage stability control in power systems. Meanwhile, existing quantifiable transient voltage indicators lack further practical applications.

[0004] Regarding control measures for transient voltage stability issues in power grids, dynamic reactive power compensation devices are commonly used in engineering projects. The most common and effective reactive power compensation devices include SVCs (Static Var Compensators), SVGs (Static Var Generators), and synchronous condensers. Furthermore, generator sets, as the main reactive power source in the power grid, have a crucial excitation capability for voltage support, but their improvement is limited by equipment capacity. Nevertheless, optimizing generator excitation control can effectively alleviate the reactive power support pressure on the receiving-end power grid after a fault and improve the network's transient voltage stability. Both generator excitation optimization and dynamic reactive power compensation can effectively improve the transient stability of the receiving-end power grid, but currently, there is a lack of an optimized control method that coordinates both.

[0005] Therefore, there is an urgent need for a transient voltage stabilization control method that coordinates generator excitation and reactive power compensation. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the defects of the existing technology and provide a transient voltage stability control method that coordinates generator excitation and reactive power compensation. First, the PMU (Phasor Measurement Unit) acquires transient voltage data of each bus in the receiving-end power grid, calculates transient voltage quantification evaluation indices, and selects nodes with severe transient voltage drops as candidate reactive power compensation nodes, and selects large-scale power plants near the target observation bus as candidate control plants. Then, based on the transient voltage quantification evaluation index values, the reactive power compensation sensitivity of each candidate reactive power compensation node is calculated, and the optimal reactive power compensation node is determined. Similarly, the parameter adjustment sensitivity of each candidate control plant is calculated, and the optimal parameter adjustment control plant is determined. Further, constraint equations for the transient voltage optimization control problem are constructed based on the compensation sensitivity of each reactive power compensation node and the parameter adjustment sensitivity of each parameter adjustment control plant. Finally, the particle swarm optimization algorithm is used to solve for the compensation capacity of each node and the adjustment range of the excitation parameters of each parameter adjustment control plant unit, thus forming a complete transient voltage optimization control method.

[0007] Therefore, one technical solution adopted by the present invention is: a transient voltage stabilization control method for coordinating generator excitation and reactive power compensation, comprising:

[0008] Step 1: Select the key bus in the receiving end power grid as the target observation bus, and use the wide-area synchronous phasor measurement device to obtain the transient voltage data of each target observation bus under the critical fault situation, and calculate the transient voltage quantitative evaluation index value of each target observation bus.

[0009] Step 2: Based on the transient voltage data of the target observation bus obtained in Step 1, select nodes with severe transient voltage drops under the corresponding fault conditions as candidate reactive power compensation nodes, and select large-scale power plants near the target observation bus as candidate control power plants.

[0010] Step 3: Based on the transient voltage quantification evaluation index values ​​of each target observation bus obtained in Step 1, calculate the reactive power compensation sensitivity of each candidate reactive power compensation node, sort the obtained reactive power compensation sensitivity from largest to smallest, and select the nodes with the highest overall ranking as the final reactive power compensation nodes.

[0011] Step 4: Based on the transient voltage quantification evaluation index values ​​of each target observation bus obtained in Step 1, calculate the parameter adjustment sensitivity of each candidate control power plant, sort the obtained parameter adjustment sensitivity from largest to smallest, and select the power plants with the highest overall ranking as the final parameter adjustment control power plants.

[0012] Step 5: For the reactive power compensation nodes and parameter-adjusting control power plants finally determined in Steps 3 and 4, construct inequality constraints for the transient voltage optimization control problem based on the reactive power compensation sensitivity of each reactive power compensation node to the target observation bus and the parameter adjustment sensitivity of each parameter-adjusting control power plant to the target observation bus. Construct the objective function with the goal of minimizing the compensation cost and parameter adjustment cost, thereby forming the mathematical description of the transient voltage optimization control problem.

[0013] Step 6: The mathematical description of the transient voltage optimization control problem formed in Step 5 is solved using the particle swarm optimization algorithm to determine the change in compensation capacity of each reactive power compensation node and the adjustment range of excitation parameters of each power plant unit under parameter control.

[0014] Furthermore, in step 1, a weighted integral is performed within each voltage drop interval to obtain the transient voltage quantitative evaluation index value of each target observation bus.

[0015] Furthermore, in step 1, the formula for calculating the transient voltage quantification evaluation index value F is as follows:

[0016]

[0017] in,

[0018] Where, Δt i Represents the time element in the integration calculation; N represents the number of time elements used in the integration calculation; M represents the number of voltage drop intervals set; K j This represents the weight corresponding to different voltage drop levels; g j (V[t i ]) is the range positioning variable for each voltage range; V[t i ] represents t i Voltage value at a given moment; V j V represents the voltage threshold of the j-th voltage drop interval. j+1 V represents the voltage threshold of the (j+1)th voltage drop interval; N This indicates the rated voltage of the busbar.

[0019] The transient voltage quantitative evaluation index value F quantifies the degree of transient voltage drop of the corresponding bus. The larger the index value, the worse the transient voltage stability of the bus. When the index value F>1, it indicates that the transient voltage of the bus is unstable, and when the index value F=1, it indicates that the transient voltage of the bus is critically stable.

[0020] Different weights are assigned to different voltage drops, with the weight increasing as the drop becomes more severe.

[0021] Furthermore, in step 3, a small-capacity reactive power device is installed at each candidate reactive power compensation node, and the reactive power compensation sensitivity is calculated by evaluating the change in the transient voltage quantification index value of the target observation bus.

[0022] Furthermore, in step 3, the formula for calculating the reactive power compensation sensitivity is:

[0023]

[0024] Among them, h ij F represents the reactive power compensation sensitivity of reactive power compensation node i to target observation bus j; j0 and F j ΔQ represents the transient voltage evaluation index value of the target observation bus j before and after compensation; i This represents the change in compensation capacity of reactive power compensation node i.

[0025] The higher the reactive power compensation sensitivity value, the better the corresponding reactive power compensation improves the transient voltage stability of the target bus.

[0026] Furthermore, in step 4, based on the transient voltage quantification evaluation index of the target observation bus, the excitation control loop V of each unit in each candidate control power plant is adjusted. RMAX The parameters are used to calculate the sensitivity of parameter tuning by quantifying the change in the transient voltage of the target observation bus.

[0027] In step 4, the formula for calculating the parameter adjustment sensitivity is:

[0028]

[0029] Among them, s mj This indicates the sensitivity of the control plant m to the parameter adjustment of the target observation bus j; F j0 and F j These represent the transient voltage quantification evaluation index values ​​of the target observation bus j before and after compensation; Δx m This indicates the adjustment range of the excitation parameters of each unit in the power plant m.

[0030] The higher the sensitivity value of the parameter adjustment, the better the effect of the corresponding power plant parameter adjustment on the transient voltage stability of the target bus.

[0031] Furthermore, in step 5, the reactive power compensation sensitivity h of each reactive power compensation node to the target observation bus is determined based on the results obtained in step 3. ij The sensitivity s of each parameter-controlled power plant to the target observation bus obtained in step 4 mjTo construct inequality constraints for the transient voltage optimization control problem, assuming there are n target observation buses, a reactive power compensation nodes, and b parameter-adjustable control power plants, the constraints representing the target control effect are as follows:

[0032]

[0033] For the objective function of the transient voltage optimization control problem, under the basic premise of achieving the target control effect, it is constructed with the goal of producing the optimal control effect with the minimum control cost, that is:

[0034]

[0035] The above constraints and objective function constitute the mathematical description of the transient voltage optimization control problem.

[0036] Furthermore, in step 5, considering the capacity of the generator excitation winding, the excitation control parameter V... RMAX The value cannot be too large, therefore an upper limit L needs to be set for each power plant under parameter control. m Thus, the constraints representing the control range limitation are constructed as follows:

[0037] Δx m ≤L m ,m=1,2,...,b (5).

[0038] Furthermore, in step 6, when solving the mathematical description of the transient voltage optimization control problem formed in step 5 using the particle swarm optimization algorithm, its spatial dimension is the sum of the number of reactive power compensation nodes and the number of parameter-controlled power plants. The constraints and objective function in step 5 are substituted into it for iterative solution, and finally the change in compensation capacity of each reactive power compensation node and the adjustment range of excitation parameters of each parameter-controlled power plant unit are determined.

[0039] The beneficial effects of this invention are as follows: This invention provides an optimized solution to the transient voltage stability control problem of the receiving-end power grid, which helps to achieve the goal of transient voltage stability improvement more economically and efficiently, and helps to achieve more effective and stable control of power system voltage. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1This is a weighted quantitative analysis diagram of the transient voltage stability margin index in a specific embodiment of the present invention;

[0042] Figure 2 This is a flowchart of the transient voltage optimization control method in a specific embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of the grid structure of the receiving-end power system studied in the application example of the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0045] Example

[0046] This embodiment provides a transient voltage stability control method that coordinates generator excitation and reactive power compensation, such as... Figure 2 As shown, the steps are as follows:

[0047] Step 1: The PMU device acquires transient voltage data of each target observation bus in the receiving-end power grid. Weighted integration is performed within each voltage drop interval to obtain the transient voltage quantitative evaluation index value of each target observation bus. The weighted quantitative analysis of the transient voltage stability margin index is as follows: Figure 1 As shown, Figure 1 In the middle, V cr.1 V cr.2 ,…,V cr.m These represent the voltage thresholds for the corresponding voltage drop intervals; t1 and t1′ represent the voltage values ​​below V during the voltage drop process. cr.1 and higher than V during recovery cr.1 At the same time, t n and t n ′ represents the moment when the voltage crosses the corresponding voltage threshold during the voltage drop and recovery processes, respectively.

[0048] The formula for calculating the transient voltage quantification evaluation index value is as follows:

[0049]

[0050] in,

[0051] Where M represents the number of voltage drop intervals set, K j The weights corresponding to different voltage drop levels are shown in the table below, which is set according to the voltage stability requirements of the power grid for each voltage drop interval:

[0052] Table 1. Weights corresponding to different voltage amplitudes

[0053]

[0054] Step 2: Based on the transient voltage data of the target observation bus obtained in Step 1, nodes with severe transient voltage drops are initially selected as candidate reactive power compensation nodes, and large-scale power plants near the target observation bus are initially selected as candidate control power plants.

[0055] Step 3: Based on the transient voltage quantification evaluation index of the target observation bus obtained in Step 1, install small-capacity reactive power devices at each candidate reactive power compensation node. Calculate the reactive power compensation sensitivity h by measuring the change in the transient voltage quantification evaluation index value of the target observation bus. The calculation formula is as follows:

[0056]

[0057] Among them, h ij F represents the reactive power compensation sensitivity of compensation node i to the target observation bus j; j0 and F j ΔQ represents the transient voltage evaluation index value of the target observation bus j before and after compensation; i This represents the change in compensation capacity of compensation node i;

[0058] The obtained reactive power compensation sensitivities are sorted from largest to smallest, and the nodes that rank at least in the top two overall are selected as the final reactive power compensation nodes.

[0059] Step 4: Based on the transient voltage quantification evaluation index of the target observation bus obtained in Step 1, adjust the excitation control loop V of each unit in the power plant controlling each candidate compensation node. RMAX The parameter, the sensitivity s, is calculated by evaluating the change in the transient voltage quantification index value of the target observation bus. The calculation formula is as follows:

[0060]

[0061] Among them, s mj F represents the parameter tuning sensitivity of candidate power plant m to target observation bus j; j0 and F j These represent the transient voltage evaluation index values ​​of the target observation bus j before and after compensation; Δx m This indicates the adjustment range of the excitation parameters of each unit in power plant m;

[0062] The obtained parameter tuning sensitivities are sorted from largest to smallest, and the power plants with the highest overall ranking are selected as the final parameter tuning control power plants.

[0063] Step 5: Based on the reactive power compensation nodes finally determined in Steps 3 and 4, and the corresponding reactive power compensation sensitivity h of the power plant under parameter adjustment control. ij and parameter adjustment sensitivity s mjTo construct inequality constraints for the transient voltage optimization control problem, assuming there are n target observation buses, a reactive power compensation nodes, and b parameter-adjustable control power plants, the constraints representing the target control effect can be constructed as follows:

[0064]

[0065] If the parameter tuning range is limited to no more than 10% of the original parameter, then the constraints representing the control range limitation are constructed as follows:

[0066] Δx m ≤L m =0.1x m0 (m=1,2,...,b) (5)

[0067] Based on reactive power compensation sensitivity h ij and parameter adjustment sensitivity s mj Construct the objective function for the transient voltage optimization control problem:

[0068]

[0069] Step 6: Substitute the constraints and objective function of the transient voltage optimization control problem obtained in Step 5 into the particle swarm optimization algorithm for solution, and finally determine the change in compensation capacity of each reactive power compensation node and the adjustment range of excitation parameters of each parameter-controlled power plant unit.

[0070] Application examples

[0071] The following application examples will demonstrate the method described in this invention.

[0072] With attachment Figure 3 Taking a certain receiving-end power network A as an example, when a critical node in the regional power grid fails, transient voltage drops will occur on each bus in the network. Based on the obtained transient voltage data of the bus, the specific comparison between the control scheme determined by the method of this invention and the simple uniform control scheme under the same control cost is shown in the following table:

[0073]

[0074] The following table compares the improvement effects of the two schemes on the transient voltage stability of the target observation bus:

[0075]

[0076] It is evident that, under the same control cost, the method obtained in this invention is more efficient and more balanced in improving the overall transient voltage stability of the system compared to a simple uniform control logic, demonstrating the effectiveness and practicality of the method in this invention.

[0077] In summary, the transient voltage stability control method for receiving-end systems that considers the coordination of generator excitation and reactive power compensation described in this invention has good effectiveness and has engineering application value.

[0078] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0079] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A transient voltage stabilization control method for coordinating generator excitation and reactive power compensation, characterized in that, include: Step 1: Select the key bus in the receiving end power grid as the target observation bus, and use the wide-area synchronous phasor measurement device to obtain the transient voltage data of each target observation bus under the critical fault situation, and calculate the transient voltage quantitative evaluation index value of each target observation bus. Step 2: Based on the transient voltage data of the target observation bus obtained in Step 1, select nodes with severe transient voltage drops under the corresponding fault conditions as candidate reactive power compensation nodes, and select large-scale power plants near the target observation bus as candidate control power plants. Step 3: Based on the transient voltage quantification evaluation index values ​​of each target observation bus obtained in Step 1, calculate the reactive power compensation sensitivity of each candidate reactive power compensation node, sort the obtained reactive power compensation sensitivity from largest to smallest, and select the nodes with the highest overall ranking as the final reactive power compensation nodes. Step 4: Based on the transient voltage quantification evaluation index values ​​of each target observation bus obtained in Step 1, calculate the parameter adjustment sensitivity of each candidate control power plant, sort the obtained parameter adjustment sensitivity from largest to smallest, and select the power plants with the highest overall ranking as the final parameter adjustment control power plants. Step 5: For the reactive power compensation nodes and parameter-adjusting control power plants finally determined in Steps 3 and 4, construct inequality constraints for the transient voltage optimization control problem based on the reactive power compensation sensitivity of each reactive power compensation node to the target observation bus and the parameter adjustment sensitivity of each parameter-adjusting control power plant to the target observation bus. Construct the objective function with the goal of minimizing the compensation cost and parameter adjustment cost, thereby forming the mathematical description of the transient voltage optimization control problem. Step 6: The mathematical description of the transient voltage optimization control problem formed in Step 5 is solved using the particle swarm optimization algorithm to determine the change in compensation capacity of each reactive power compensation node and the adjustment range of excitation parameters of each power plant unit under parameter control.

2. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 1, characterized in that, In step 1, a weighted integral is performed within each voltage drop interval to obtain the transient voltage quantitative evaluation index value of each target observation bus.

3. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 2, characterized in that, In step 1, the formula for calculating the transient voltage quantification evaluation index value F is as follows: in, Where, Δt i Represents the time element in the integration calculation; N represents the number of time elements used in the integration calculation; M represents the number of voltage drop intervals set; K j This represents the weight corresponding to different voltage drop levels; g j (V[t i ]) is the range positioning variable for each voltage range; V[t i ] represents t i Voltage value at a given moment; V j V represents the voltage threshold of the j-th voltage drop interval. j+1 V represents the voltage threshold of the (j+1)th voltage drop interval; N Indicates the rated voltage of the busbar; When the index value F>1, it indicates that the bus transient voltage is unstable; when the index value F=1, it indicates that the bus transient voltage is critically stable.

4. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 1, characterized in that, In step 3, a small-capacity reactive power device is installed at each candidate reactive power compensation node, and the reactive power compensation sensitivity is calculated by the change of the transient voltage quantification evaluation index value of the target observation bus.

5. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 4, characterized in that, In step 3, the formula for calculating the reactive power compensation sensitivity is: Among them, h ij F represents the reactive power compensation sensitivity of reactive power compensation node i to target observation bus j; j0 and F j ΔQ represents the transient voltage evaluation index value of the target observation bus j before and after compensation; i This represents the change in compensation capacity of reactive power compensation node i.

6. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 5, characterized in that, In step 4, based on the transient voltage quantification evaluation index of the target observation bus, the excitation control loop V of each unit in each candidate control power plant is adjusted. RMAX The parameters are used to calculate the sensitivity of parameter tuning by quantifying the change in the transient voltage of the target observation bus.

7. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 6, characterized in that, In step 4, the formula for calculating the parameter adjustment sensitivity is: Among them, s mj This indicates the sensitivity of the control plant m to the parameter adjustment of the target observation bus j; F j0 and F j These represent the transient voltage quantification evaluation index values ​​of the target observation bus j before and after compensation; Δx m This indicates the adjustment range of the excitation parameters of each unit in the power plant m.

8. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 7, characterized in that, In step 5, the reactive power compensation sensitivity h of each reactive power compensation node to the target observation bus is obtained from step 3. ij The sensitivity s of each parameter-controlled power plant to the target observation bus obtained in step 4 mj To construct inequality constraints for the transient voltage optimization control problem, assuming there are n target observation buses, a reactive power compensation nodes, and b parameter-adjustable control power plants, the constraints representing the target control effect are as follows: For the objective function of the transient voltage optimization control problem, under the basic premise of achieving the target control effect, it is constructed with the goal of producing the optimal control effect with the minimum control cost, that is: The above constraints and objective function constitute the mathematical description of the transient voltage optimization control problem.

9. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 8, characterized in that, In step 5, considering the generator excitation winding's bearing capacity, the excitation control parameter V... RMAX The value cannot be too large, therefore an upper limit L needs to be set for each power plant under parameter control. m Thus, the constraints representing the control range limitation are constructed as follows: Δx m ≤L m ,m=1,2,...,b。 10. The transient voltage stabilization control method for coordinating generator excitation and reactive power compensation according to claim 1 or 8, characterized in that, In step 6, the mathematical description of the transient voltage optimization control problem formed in step 5 is solved using the particle swarm optimization algorithm. Its spatial dimension is the sum of the number of reactive power compensation nodes and the number of power plants under parameter adjustment control. The constraints and objective function in step 5 are substituted into it for iterative solution, and finally the change in compensation capacity of each reactive power compensation node and the adjustment range of excitation parameters of each power plant unit under parameter adjustment control are determined.

Images