Parameter optimization method for suppressing transient overvoltage of new energy AC / DC delivery system

Abstract

The invention provides a parameter optimization method and device for suppressing transient overvoltage of a new energy AC / DC delivery system and a storage medium, which can identify key parameters influencing the transient voltage stability in the new energy AC / DC delivery system and optimize the values of the key parameters, thereby effectively reducing the transient overvoltage after a fault. According to the method, the transient voltage rise is taken as an index, the sensitivity coefficient of the transient voltage rise to each control parameter is calculated by using a global sensitivity analysis method, the key rank of each parameter under various operation conditions is obtained, and the key parameter influencing the transient overvoltage is identified. And then, based on the cosine similarity theorem, analyzing the interaction among the key influence parameters. And finally, by taking the minimum transient voltage rise as a target, optimizing key parameter values, so that the transient overvoltage of the system after the fault is reduced, the transient voltage stability of the system is improved, and the problem that the setting basis of the parameter values of the control strategy is insufficient is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of transient stability analysis and control of new energy power systems, and specifically relates to a parameter optimization method, device and storage medium for suppressing transient overvoltage in new energy AC / DC transmission systems. Background Art

[0002] At present, new energy installed capacity such as wind power generation and solar photovoltaic power generation has become an important part of my country's total installed power generation capacity. At the same time, UHV DC transmission technology plays an important role in large-scale new energy grid connection and long-distance power transmission. my country has built a number of UHV transmission projects and created a UHV AC / DC hybrid power grid. The new energy AC / DC transmission system is an important scenario for the large-scale development and consumption of new energy electricity in my country. Unlike synchronous generators and AC transformers, new energy and DC transmission use power electronic equipment to connect to the grid. Its control strategy is complex and it is difficult to provide good reactive power support for the system, which leads to overvoltage in the system when a fault occurs, thereby deteriorating transient voltage stability. At present, the new energy AC / DC transmission system has deployed a series of control measures to deal with faults, including low-voltage ride-through control of new energy power sources, DC control link of DC transmission, and low-voltage current limiting link.

[0003] These control strategies have many control parameters, and the values ​​of the control parameters have a significant impact on the transient overvoltage after the fault. At present, the setting of control parameters mainly relies on experience, and there is still a lack of a complete theoretical framework to guide the specific numerical setting of these parameters. Therefore, it is necessary to deeply explore the influence of multiple controllable parameter values ​​on the transient overvoltage after the fault of the new energy AC / DC transmission system, and propose a scientific and reasonable parameter determination method to improve the transient voltage stability of the system, so as to provide a strong guarantee for the large-scale long-distance new energy development and utilization. Summary of the invention

[0004] In view of this, the present invention provides a parameter optimization method for suppressing transient overvoltage in new energy AC / DC transmission systems, which can reveal the influence of parameters in multiple control links on transient overvoltage after system failure, and optimize the parameter values, thereby improving the transient voltage stability of new energy AC / DC transmission systems.

[0005] In order to solve the above technical problems, the present invention is implemented as follows.

[0006] A parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system, wherein the transient overvoltage is suppressed by suppressing a transient voltage rise of the system after a system failure; the method comprises:

[0007] Determine the controllable parameter combination of the new energy AC / DC transmission system;

[0008] Construct different value schemes for the combination of controllable parameters; simulate the operation of the new energy AC / DC transmission system under each value scheme, obtain the transient voltage rise of the system after the fault corresponding to the current value scheme, and determine the sensitivity of the system transient voltage rise to the controllable parameters. According to the sensitivity determination results of all value schemes, identify the controllable parameters that affect the system transient voltage rise as the key influencing parameters of the system transient overvoltage;

[0009] With the goal of minimizing transient voltage rise, the key influencing parameters are optimized.

[0010] Preferably, the optimization of the key influencing parameters with the goal of minimizing the transient voltage rise is as follows: analyzing the interaction between the key influencing parameters based on cosine similarity; when it is determined that there is interaction between the key influencing parameters, the identified key influencing parameters have room for optimization, and the key influencing parameters are optimized using an intelligent optimization algorithm; otherwise, for each key influencing parameter, other parameters are controlled to remain unchanged, and the influence of the current key influencing parameters on the transient voltage rise is obtained through simulation, and the parameter value when the transient voltage rise is minimized is used as the optimal value of the current key influencing parameter, and this process ends.

[0011] Preferably, the interaction between the key influencing parameters based on the cosine similarity analysis is:

[0012] For the i-th parameter y among the key influencing parameters i , fix the values ​​of other key influencing parameters, and obtain the transient voltage rise of the system with parameter y i The curve of the change; changing the value of the remaining key influencing parameters to obtain multiple curves; calculating the cosine similarity between the curves, and judging whether the cosine similarity is greater than the set similarity threshold, if so, judging the remaining key influencing parameters on the parameter y i There is an interaction relationship; otherwise, it is determined that there is no interaction relationship;

[0013] If each key influencing parameter does not interact with the other key influencing parameters, it is determined that there is no interaction between the key influencing parameters; as long as any key influencing parameter interacts with the other key influencing parameters, it is determined that there is room for optimization for each key influencing parameter.

[0014] Preferably, the system fault is a DC commutation failure fault; the system transient voltage rise calculation formula is as follows:

[0015] ΔU=U max -U0

[0016] Among them, ΔU is the transient voltage rise of the system after the fault, U max is the maximum value of the system transient overvoltage after the fault, and U0 is the initial value of the system voltage before the fault occurs.

[0017] Preferably, the determined controllable parameter combination includes: the active current percentage I of the wind turbine during the low voltage ride-through process p , Active power recovery rate v p and reactive power adjustment coefficient; the minimum interpolation current command, start voltage and exit voltage of the low voltage current limiting control VDCOL link; the proportional gain and integral time constant T of the current control amplifier CCA link on the DC rectifier side i_CCA .

[0018] Preferably, the operation of the new energy AC / DC transmission system is simulated to obtain the transient voltage rise of the system after the fault corresponding to the current value scheme:

[0019] Step A1: Use the power system electromechanical transient simulation tool to build a simulation model of the new energy AC / DC transmission system, set the DC commutation failure fault, and obtain the simulation result of the system voltage curve after the fault;

[0020] Step A2: Use programming software to modify the values ​​of controllable parameters in the electromechanical transient simulation tool, simulate the electromechanical transient simulation tool to obtain the system voltage curve, and the programming tool reads the system voltage curve and calculates the system transient voltage rise.

[0021] Preferably, the sensitivity of the system transient voltage rise to the controllable parameters is determined, and the controllable parameters affecting the system transient voltage rise are identified as key influencing parameters of the system transient overvoltage according to the sensitivity determination results of all value taking schemes, specifically:

[0022] Step B1: for each value scheme: increase the value of each controllable parameter at the same percentage, and obtain the transient voltage rise ΔU of the system after the controllable parameter value is increased. + ; Reduce the value of each controllable parameter by the same percentage at the same time, and obtain the transient voltage rise ΔU of the system after the controllable parameter is reduced - ; Using ΔU + and ΔU - Calculate the sensitivity coefficient of each controllable parameter;

[0023] Step B3, under each value selection scheme, all controllable parameters are sorted according to the sensitivity coefficient of each controllable parameter, the frequency of each controllable parameter ranking in the top n positions of the setting is counted, and the m controllable parameters with the highest frequency are selected as the key influencing parameters of the system transient overvoltage identified;

[0024] Among them, the value of m is greater than or equal to 3 and less than the number of controllable parameters in the controllable parameter combination; the value of n is 30% to 50% of the number of controllable parameters in the controllable parameter combination, and n is greater than or equal to 3.

[0025] Preferably, the sensitivity coefficient calculation formula of the controllable parameter is:

[0026]

[0027] Among them, x i is the value of the i-th controllable parameter in the controllable parameter combination without increasing or decreasing; S i is the i-th controllable parameter x i Sensitivity coefficient; ΔU + and ΔU - are the controllable parameters x i The transient voltage rise of the new energy AC / DC transmission system corresponding to the increase and decrease; Δx i+ and Δx i- is the increase and decrease of the i-th parameter; ΔU is the controllable parameter x i The corresponding system transient voltage rise when no increase or decrease is made.

[0028] Preferably, the use of an intelligent optimization algorithm to optimize the key influencing parameters includes: using a particle swarm algorithm to optimize the values ​​of the key influencing parameters so as to minimize the transient voltage rise.

[0029] Preferably, the system transient voltage rise adopts one or a weighted sum of the transient voltage rise of the DC sending end bus of the new energy AC / DC transmission system and the transient voltage rise of the wind turbine end bus.

[0030] The present invention also provides a parameter optimization device for suppressing transient overvoltage in a new energy AC / DC transmission system, the device comprising a controllable parameter combination determination module, a key influencing parameter identification module, and an optimization module;

[0031] The controllable parameter combination determination module is used to determine the controllable parameter combination of the new energy AC / DC transmission system;

[0032] The key influencing parameter identification module is used to construct different value schemes for the controllable parameter combination; under each value scheme, the operation of the new energy AC / DC transmission system is simulated to obtain the transient voltage rise of the system after the fault corresponding to the current value scheme, and determine the sensitivity of the system transient voltage rise to the controllable parameters, and identify the controllable parameters that affect the system transient voltage rise according to the sensitivity determination results of all value schemes as the key influencing parameters of the system transient overvoltage;

[0033] The optimization module is used to optimize the key influencing parameters identified by the key influencing parameter identification module with the goal of minimizing transient voltage rise.

[0034] Preferably, the optimization module includes an interaction analysis submodule, a first optimization submodule and a second optimization submodule;

[0035] The interaction analysis submodule is used to analyze the interaction between the key influencing parameters based on cosine similarity; when it is determined that there is interaction between the key influencing parameters, the identified key influencing parameters have optimization space, and the first optimization submodule is notified to work; otherwise, the second optimization submodule is notified to work;

[0036] The first optimization submodule is used to optimize the key influencing parameters using an intelligent optimization algorithm;

[0037] The second optimization submodule is used to control other parameters unchanged for each key influencing parameter, obtain the influence of the current key influencing parameter on the transient voltage rise through simulation, and take the parameter value when the transient voltage rise is the smallest as the optimal value of the current key influencing parameter.

[0038] The present invention further provides a computer-readable storage medium having computer instructions stored thereon, characterized in that when the instructions are executed by a processor, the steps in the parameter optimization method for suppressing transient overvoltages in the new energy AC / DC transmission system can be implemented.

[0039] Beneficial effects:

[0040] (1) The global sensitivity analysis method adopted by the present invention comprehensively analyzes the sensitivity of the system transient voltage rise to the controllable parameters under different parameter value combinations in multiple control links, thereby identifying the key influencing parameters of the system transient voltage and improving the credibility of the analysis results. During the analysis process, the system transient voltage rise is obtained through the simulation of the new energy AC / DC transmission system, the data is accurate, and complex formula derivation is avoided, which improves the simulation efficiency and the accuracy of the simulation results.

[0041] (2) In a preferred embodiment, after the key influencing parameters are identified, the interaction between the key influencing parameters is further analyzed based on the cosine similarity. When the interaction occurs, it indicates that the identified key influencing parameters have optimization space, and the parameters are optimized with the minimum transient voltage rise as the goal. This makes the obtained optimization parameters more accurate. When there is no interaction, it is not necessary to optimize the intelligent algorithm, which reduces the computational difficulty of the parameter optimization process.

[0042] (3) The present invention realizes efficient modification of parameter values ​​in multiple control links of the new energy AC / DC transmission system by jointly calling the power system electromechanical transient simulation tool and programming software.

[0043] (4) The present invention fully explores the influence of key influencing parameters on the system transient voltage and the interaction between parameters, provides a theoretical basis for the optimization of key influencing parameters, and then optimizes the key influencing parameters using an intelligent optimization algorithm, providing system operators with reliable recommended values ​​of key influencing parameters, which has practical engineering significance and ensures the safe operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of a new energy AC / DC transmission simulation system according to an embodiment of the present invention.

[0045] Figure 2 The figure is a flow chart of a transient overvoltage suppression method according to an embodiment of the present invention.

[0046] Figure 3 This is a flow chart of identifying key influencing parameters according to the global sensitivity analysis method according to an embodiment of the present invention.

[0047] Figure 4 This is a flow chart of key influencing parameters of the particle swarm algorithm optimization system according to an embodiment of the present invention.

[0048] Figure 5 It is a schematic diagram of the composition of a parameter optimization device for suppressing transient overvoltage in a new energy AC / DC transmission system according to an embodiment of the present invention.

[0049] Figure 6 for Figure 5 The composition block diagram of the key influencing parameter identification module.

[0050] Figure 7 for Figure 5 The block diagram of the optimization module. DETAILED DESCRIPTION

[0051] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0052] The present invention provides a parameter optimization method for suppressing transient overvoltage of a new energy AC / DC transmission system. The basic idea is: suppressing transient overvoltage is achieved by suppressing the transient voltage rise of the system after a system fault; first determine the controllable parameter combination of the new energy AC / DC transmission system; then construct different value schemes for the controllable parameter combination; under each value scheme, simulate the operation of the new energy AC / DC transmission system, obtain the transient voltage rise of the system after the fault corresponding to the current value scheme, and determine the sensitivity of the transient voltage rise of the system to the controllable parameters, and identify the controllable parameters that affect the transient voltage rise of the system according to the sensitivity determination results of all value schemes, as the key influencing parameters of the system transient overvoltage. With the goal of minimizing the transient voltage rise, optimize the key influencing parameters.

[0053] It can be seen that the global sensitivity analysis method adopted by the present invention comprehensively analyzes the sensitivity of the system transient voltage rise to the controllable parameters under different parameter value combinations in multiple control links, thereby identifying the key influencing parameters of the system transient voltage and improving the credibility of the analysis results. During the analysis process, the system transient voltage rise is obtained through the simulation of the new energy AC / DC transmission system, the data is accurate, and complex formula derivation is avoided, which improves the simulation efficiency and the accuracy of the simulation results.

[0054] In a preferred embodiment, after the key influencing parameters are identified, the interaction between the key influencing parameters is further analyzed based on cosine similarity. When the interaction occurs, it indicates that the identified key influencing parameters have optimization space, and the parameters are optimized with the minimum transient voltage rise as the goal. This makes the obtained optimization parameters more accurate. When there is no interaction, it is not necessary to optimize the intelligent algorithm, which reduces the computational difficulty of the parameter optimization process.

[0055] The specific implementation process of the parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system of the present invention is described in detail below.

[0056] The parameter optimization method for suppressing transient overvoltage of new energy AC / DC transmission system proposed in the embodiment first constructs a simulation model of new energy AC / DC transmission system, and jointly calls the power system electromechanical transient simulation tool PSD-BPA and the programming software MATLAB to realize automatic parameter modification and voltage simulation result acquisition, which solves the shortcomings of traditional mechanism analysis, such as high complexity, low efficiency and many simplified assumptions. Then, the Monte Carlo sampling method and the sensitivity analysis method are combined to accurately identify the key influencing parameters of system transient overvoltage, and the cosine similarity theorem is used to explore the influence of the key influencing parameters on the system transient voltage and the interaction between the parameters, which provides a theoretical basis for the optimization of the key influencing parameters. Finally, the key influencing parameters of system transient overvoltage are optimized based on the particle swarm algorithm, which makes up for the current problems of inaccurate optimization identification and optimization difficulty of key parameters, and provides an important basis for suppressing transient overvoltage of new energy AC / DC transmission system.

[0057] Figure 1 It is a structural schematic diagram of a simulation model of a new energy AC / DC transmission system according to an embodiment of the present invention, including two thermal power generating units, two wind power generating units, and high-voltage DC transmission and AC transmission lines.

[0058] Figure 2 This is a flow chart of a transient overvoltage suppression method according to an embodiment of the present invention, which specifically includes the following steps:

[0059] Step 1: Build a simulation model of the new energy AC / DC transmission system and jointly call the power system electromechanical transient simulation tool PSD-BPA and programming software MATLAB to modify the controllable parameters and obtain the system transient voltage simulation results.

[0060] Step 2: Determine the controllable parameter combination of the new energy AC / DC transmission system.

[0061] exist Figure 1In the new energy AC / DC transmission system shown, controllable parameters in the active and reactive control strategies of the wind turbine during low voltage ride-through are selected. The active control method during the low voltage ride-through period is to specify the percentage of active current to the initial current, and the active climbing process increases at a fixed slope. The reactive control method during the low voltage ride-through period adopts the voltage control reactive current method, and changes the reactive adjustment coefficient to optimize the control effect. Specifically, the selectable parameters are: active current percentage, active recovery rate and reactive adjustment coefficient.

[0062] Select the controllable parameters in the VDCOL (Voltage Dependent Current Order Limiter, low voltage current limiting control) link. When the DC voltage drops to the set value, the reactive power demand of the DC system on the AC system is reduced by limiting the DC current command value, which is conducive to quickly improving the AC voltage and is used to suppress continuous commutation failure. The control method can be described as:

[0063]

[0064] In the specific setting, the low voltage current limit output limit value I dh It is usually set to the rated current. Specifically, the parameters that can be selected are: I dh ,I dl , U dh and U dl , which are the maximum current instruction, minimum current instruction, starting voltage and exit voltage of the VDCOL link respectively.

[0065] Considering the controllable parameters of the CCA (Current Control Amplifier) ​​link on the DC rectifier side, when the DC current measurement value deviates from the DC current command value on the rectifier side, the current difference is eliminated by controlling the trigger angle on the rectifier side to maintain the DC current constant. The control method can be described as:

[0066]

[0067] Among them, α R is the trigger angle on the rectifier side, α0 is the initial trigger angle, I dmeas is the DC current measurement value, I ord is the DC current command value on the rectifier side. Specifically, the parameters that can be selected are: the proportional adjustment coefficient k of the PI controller p and the integration time constant T i_CCA .

[0068] In summary, the controllable parameter combination determined in this embodiment includes: the active current percentage I of the wind turbine during the low voltage ride-through process p , Active power recovery rate v pand reactive power adjustment coefficient; minimum interpolation current command, start voltage and exit voltage of VDCOL link; proportional gain and integral time constant T of CCA link i_CCA .

[0069] Step 3: Construct different value schemes for the controllable parameter combinations; under each value scheme, simulate the operation of the new energy AC / DC transmission system to obtain the transient voltage rise of the system after the fault corresponding to the current value scheme.

[0070] The present invention suppresses transient overvoltage by suppressing the transient voltage rise of the system after a system fault. The fault is selected as a DC commutation failure fault. The simulation result needs to be used to calculate the transient voltage rise of the system after the fault. The calculation formula is:

[0071] ΔU=U max -U0

[0072] Among them, ΔU is the transient voltage rise of the system after the fault, U max is the maximum value of the system transient overvoltage after the fault, and U0 is the initial value of the system voltage before the fault occurs.

[0073] The specific implementation process of this step is:

[0074] Step A1: Generate all possible value combinations of controllable parameters based on the Monte Carlo sampling method, and each combination is used as a value scheme.

[0075] Within the controllable parameter optimization range of this embodiment, the method for randomly sampling the value combinations of various parameters is:

[0076]

[0077] Among them, x imin and x imax are the lower and upper limits of the value of the i-th key influencing parameter, r ii A random number generated when sampling the value of the key influencing parameter i.

[0078] Step A2: For each value selection scheme, a simulation model of the new energy AC / DC transmission system is built using a power system electromechanical transient simulation tool, and a DC commutation failure fault is set to obtain a simulation result of the system voltage curve after the fault;

[0079] Step A3: Use programming software to modify the values ​​of controllable parameters in the electromechanical transient simulation tool, simulate the system voltage curve through the electromechanical transient simulation tool, and finally read the system voltage curve through the programming tool to calculate the system transient voltage rise.

[0080] Step A4: For each value selection scheme, the combined calling method of steps A1-A2 is used to obtain the transient voltage rise of the system under each value selection scheme.

[0081] Step 4: Determine the sensitivity of the system transient voltage rise to the controllable parameters, determine the results based on the sensitivity of all value selection schemes, and select the controllable parameters with higher sensitivity as the key influencing parameters of the system transient overvoltage.

[0082] Figure 3 The specific steps of parameter sensitivity analysis are shown, including the following sub-steps:

[0083] Step B1: for each value scheme: increase the value of each controllable parameter at the same percentage (e.g., 20%) to obtain the transient voltage rise ΔU of the system after the controllable parameter value is increased. + ; Reduce the value of each controllable parameter by the same percentage at the same time, and obtain the transient voltage rise ΔU of the system after the controllable parameter is reduced - ; Using ΔU + and ΔU - Calculate the sensitivity coefficient of each controllable parameter.

[0084] The sensitivity coefficient calculation formula is:

[0085]

[0086] Among them, x i is the value of the i-th controllable parameter in the controllable parameter combination without increasing or decreasing; S i is the i-th controllable parameter x i Sensitivity coefficient; ΔU + and ΔU - are the controllable parameters x i The transient voltage rise of the new energy AC / DC transmission system corresponding to the increase and decrease; Δx i+ and Δx i- is the increase and decrease of the i-th parameter; ΔU is the controllable parameter x i The corresponding system transient voltage rise when no increase or decrease is made.

[0087] Step B2: for each of all value taking schemes, sort all controllable parameters from large to small according to the sensitivity coefficient.

[0088] Step B3: Count the frequency of each controllable parameter ranking in the top n positions of the setting. The value of n is 30% to 50% of the number of controllable parameters in the controllable parameter combination, and n is greater than or equal to 3.

[0089] Step B4: Take the m controllable parameters with the highest frequency as the identified key influencing parameters of the system transient overvoltage, wherein the value of m is greater than or equal to 3 and less than the number of controllable parameters in the controllable parameter combination.

[0090] In a preferred embodiment, m=3, n=3, and the frequency of each controllable parameter ranking in the top 3 is counted, and the 3 controllable parameters with the highest frequency are selected as the key influencing parameters. In this embodiment, the 3 key influencing parameters selected by sensitivity coefficient calculation and sorting identification are: the percentage of active current I during the low voltage ride-through process of the wind turbine p , Active power recovery rate v p and the integral time constant T of the CCA link i_CCA .

[0091] Step 5: Analyze the interaction between key influencing parameters based on cosine similarity.

[0092] In this step, based on the cosine similarity analysis, it is judged whether there is interaction between the key influencing parameters. When it is determined that there is interaction between the key influencing parameters, the identified key influencing parameters have optimization space and need to be jointly optimized, then step 6 is executed to jointly optimize the key influencing parameters using an intelligent optimization algorithm; otherwise, step 7 is executed to obtain the optimal value according to the influence of the key influencing parameters on the transient voltage rise of the system.

[0093] The specific judgment method based on cosine similarity is as follows:

[0094] For the i-th parameter y among the key influencing parameters i , fix the values ​​of other key influencing parameters, and obtain the transient voltage rise of the system with parameter y i The changed curve; changing the values ​​of the remaining key influencing parameters to obtain multiple curves; calculating the cosine similarity between the curves, the calculation formula is as follows:

[0095]

[0096] Among them, A i , B i When a certain set of values ​​is taken for the other key parameters, the transient voltage rise of the system changes with the key influencing parameter y i The sequence vector of the changing curve, θ i is the angle between the two sets of vectors. i The range is between [-1,1], θ i =1The two vectors have the maximum similarity, θ i = 0 means that the two vectors are completely unrelated, θ i = -1 means that the two vectors are completely dissimilar. By setting the similarity threshold θ th , judgment curve A i , B i Are they similar? The similarity threshold is set to 0.7, for example. i Greater than θ th , then we think A i , Bi Similarly, the other key parameters are related to the parameter y i There is an interaction relationship; otherwise, it is determined that there is no interaction relationship;

[0097] If for each key influencing parameter, no interaction occurs no matter how the other key influencing parameters change, the optimal value can be obtained according to the influence law of the key influencing parameter on the transient voltage rise of the system; as long as any key influencing parameter interacts with the other key influencing parameters, it is determined that there is room for optimization for each key influencing parameter, and the key influencing parameters need to be further jointly optimized.

[0098] Step 6: The key influencing parameters interact with each other: With the goal of minimizing transient voltage rise, the intelligent optimization algorithm is used to optimize the key influencing parameters. At this point, the parameter optimization is completed.

[0099] In a preferred embodiment, a particle swarm algorithm is used to optimize the key influencing parameters of the new energy AC / DC transmission power system model. Using the particle swarm algorithm, multiple key influencing parameters can be optimized simultaneously through the multidimensional characteristics of the position within a given parameter space, which is suitable for parameter optimization problems. The specific implementation can be: using a joint call method, based on an intelligent optimization algorithm, the key influencing parameters are optimized with the minimum transient voltage rise of the new energy AC / DC transmission system as the optimization goal, and the objective function and constraints are as follows:

[0100] 1) Objective function

[0101] The key control parameters are optimized with the minimum transient voltage rise of the new energy AC / DC transmission system as the optimization goal. The transient voltage rise of the system is characterized by the weighted transient voltage rise of the DC transmission end bus and the wind turbine end bus. The objective function is as follows:

[0102] minf=w1ΔU LCC +(1-w1)ΔU Wind

[0103] Among them, w1 is the weight coefficient, which can be adjusted according to actual engineering needs, ΔU LCC and ΔU Wind They are respectively the transient voltage rise of the DC sending end bus and the wind turbine end bus of the new energy AC / DC transmission system. In the above, the transient voltage rise mentioned can also be one of the DC sending end bus and the wind turbine end bus or their weighted sum.

[0104] 2) Constraints

[0105] All key influencing parameters are constrained within reasonable ranges.

[0106]

[0107] Among them, Ip 、v p 、T i_CCA are respectively the active current percentage, active recovery rate and integral time constant of CCA link during low voltage ride-through of wind turbine, I pmin ,I pmax 、v pmin 、v pmax 、T i_CCAmin 、T i_CCAmax are the upper and lower limits of the corresponding parameters respectively.

[0108] Figure 4 This is a flow chart of key influencing parameters of the particle swarm algorithm optimization system according to an embodiment of the present invention, which specifically includes the following steps:

[0109] Step C1: Initialize the key influencing parameter values. In this embodiment, the position of each individual is composed of a 3D feature consisting of three key influencing parameters. The three key influencing parameters are: active current percentage, proportional gain of the CCA link, and integral time constant. The individual optimizes its own position based on its own inertia, self-cognition, and group cognition.

[0110] Step C2: Input the key influencing parameter values ​​into the PSD-BPA tool for simulation to obtain the voltage curve;

[0111] Step C3: MATLAB reads the transient voltage curve and obtains the transient voltage rise value;

[0112] Step C4: Calculate the objective function value:

[0113] minf=w1ΔU LCC +(1-w1)ΔU Wind

[0114] Among them, w1 controls the trade-off between the transient voltage rise at the LCC grid connection point and the transient voltage rise at the machine end. The closer its value is to 1, the more attention is paid to the transient voltage rise at the LCC grid connection point, and it can be flexibly adjusted as needed.

[0115] Step C5: Update the values ​​of individual and global optimal key influencing parameters;

[0116] Step C6: Update key parameter values:

[0117] In this step, update your movement speed according to the following formula:

[0118] v i =w×v i +c1×r1×(pbest i -x i )+c2×r2×(gbest i -x i )

[0119] Among them, w is the inertia factor. The larger its value, the stronger the global optimization ability is and the weaker the local optimization ability is. c1 and c2 are learning factors. pbest i 、gbest i are the individual historical optimal value and the global historical optimal value of individual i respectively, r1 and r2 are random numbers.

[0120] Then update its own position in the next step according to the speed to search for the optimal position:

[0121] x i =x i +v i

[0122] Step C7: Determine whether convergence has occurred. If convergence has occurred, output the optimal key parameter value. Otherwise, loop through steps C2-C7.

[0123] The key influencing parameter values ​​optimized by the particle swarm algorithm are compared with the system voltage curve obtained under the typical values ​​of each parameter. The key influencing parameter values ​​after particle swarm optimization can significantly reduce the transient overvoltage of the system, ensuring the safety of system operation while effectively suppressing the transient overvoltage of the system.

[0124] Step 7: There is no interaction between the key influencing parameters: for each key influencing parameter, control other parameters unchanged, obtain the influence of the current key influencing parameter on the transient voltage rise through simulation, and take the parameter value when the transient voltage rise is the smallest as the optimal value of the current key influencing parameter. At this point, the parameter optimization is completed.

[0125] Figure 5 The schematic diagram of the structure of the parameter optimization device for suppressing transient overvoltage in the AC / DC transmission system of new energy according to the embodiment of the present invention is shown. As shown in the figure, the device includes a controllable parameter combination determination module, a key influencing parameter identification module, and an optimization module;

[0126] The controllable parameter combination determination module is used to determine the controllable parameter combination of the new energy AC / DC transmission system.

[0127] In an optional solution, the controllable parameter combination includes: the active current percentage I of the wind turbine during the low voltage ride-through process p , Active power recovery rate v p and reactive power adjustment coefficient; the minimum interpolation current command, start voltage and exit voltage of the low voltage current limiting control VDCOL link; the proportional gain and integral time constant T of the current control amplifier CCA link on the DC rectifier side i_CCA .

[0128] The key influencing parameter identification module is used to construct different value schemes for the controllable parameter combination; under each value scheme, the operation of the new energy AC / DC transmission system is simulated to obtain the transient voltage rise of the system after the fault corresponding to the current value scheme, and determine the sensitivity of the system transient voltage rise to the controllable parameters. According to the sensitivity determination results of all value schemes, the controllable parameters that affect the system transient voltage rise are identified as the key influencing parameters of the system transient overvoltage.

[0129] The sensitivity coefficient calculation formula is:

[0130]

[0131] Among them, x i is the value of the i-th controllable parameter in the controllable parameter combination without increasing or decreasing; S i is the i-th controllable parameter x i Sensitivity coefficient; ΔU + and ΔU - are the controllable parameters x i The transient voltage rise of the new energy AC / DC transmission system corresponding to the increase and decrease; Δx i+ and Δx i- is the increase and decrease of the i-th parameter; ΔU is the controllable parameter x i The corresponding system transient voltage rise when no increase or decrease is made.

[0132] The optimization module is used to optimize the key influencing parameters identified by the key influencing parameter identification module with the goal of minimizing transient voltage rise.

[0133] In an optional embodiment, the key influencing parameter identification module is as follows: Figure 6 As shown, it specifically includes a value scheme construction submodule, a fault simulation module submodule, a sensitivity calculation submodule, and an identification submodule;

[0134] The value scheme construction submodule is used to construct different value schemes for the controllable parameter combination within its value range according to the controllable parameter combination.

[0135] The fault simulation module submodule is used to simulate the operation of the new energy AC / DC transmission system under each value scheme, and obtain the transient voltage rise of the system after the fault corresponding to the current value scheme. Specifically: use the power system electromechanical transient simulation tool to build a simulation model of the new energy AC / DC transmission system, set the DC commutation failure fault, and obtain the simulation result of the system voltage curve after the fault; use the programming software to modify the value of the controllable parameters in the electromechanical transient simulation tool, and simulate the system voltage curve through the electromechanical transient simulation tool. The programming tool reads the system voltage curve and calculates the system transient voltage rise.

[0136] The system fault is a DC commutation failure fault; the system transient voltage rise calculation formula is as follows:

[0137] ΔU=U max -U0

[0138] Among them, ΔU is the transient voltage rise of the system after the fault, U max is the maximum value of the system transient overvoltage after the fault, and U0 is the initial value of the system voltage before the fault occurs.

[0139] The sensitivity calculation submodule is used to determine the sensitivity of the system transient voltage rise to the controllable parameters for each value scheme; specifically, for each value scheme: increase the value of each controllable parameter at the same percentage at the same time, and obtain the system transient voltage rise ΔU after the controllable parameter value is increased. + ; Reduce the value of each controllable parameter by the same percentage at the same time, and obtain the transient voltage rise ΔU of the system after the controllable parameter is reduced - ; Using ΔU + and ΔU - Calculate the sensitivity coefficient of each controllable parameter; under each value scheme, sort all controllable parameters according to the sensitivity coefficient of each controllable parameter, count the frequency of each controllable parameter ranking in the top n positions of the setting, and take the m controllable parameters with the highest frequency as the key influencing parameters of the identified system transient overvoltage; wherein, the value of m is greater than or equal to 3 and less than the number of controllable parameters in the controllable parameter combination; the value of n is 30% to 50% of the number of controllable parameters in the controllable parameter combination, and n is greater than or equal to 3.

[0140] The identification submodule is used to identify the controllable parameters that affect the transient voltage rise of the system according to the sensitivity calculation results, as the key influencing parameters of the transient overvoltage of the system.

[0141] In an optional embodiment, the optimization module is as follows Figure 7 As shown, it specifically includes an interaction analysis submodule, a first optimization submodule and a second optimization submodule;

[0142] The interaction analysis submodule is used to analyze the interaction between key influencing parameters based on cosine similarity; when it is determined that there is interaction between the key influencing parameters, the identified key influencing parameters have optimization space, and the first optimization submodule is notified to work; otherwise, the second optimization submodule is notified to work.

[0143] Among them, when analyzing the interaction between key influencing parameters based on cosine similarity, for the i-th parameter y in the key influencing parameter i , fix the values ​​of other key influencing parameters, and obtain the transient voltage rise of the system with parameter y iThe curve of the change; changing the value of the remaining key influencing parameters to obtain multiple curves; calculating the cosine similarity between the curves, and judging whether the cosine similarity is greater than the set similarity threshold, if so, judging the remaining key influencing parameters on the parameter y i If there is an interaction relationship, then it is determined that there is no interaction relationship. If each key influencing parameter does not interact with the other key influencing parameters, then it is determined that there is no interaction between the key influencing parameters. As long as there is an interaction between any key influencing parameter and the other key influencing parameters, then it is determined that there is room for optimization for each key influencing parameter.

[0144] A first optimization submodule, used to optimize the key influencing parameters using an intelligent optimization algorithm;

[0145] The second optimization submodule is used to control other parameters unchanged for each key influencing parameter, obtain the influence of the current key influencing parameter on the transient voltage rise through simulation, and take the parameter value when the transient voltage rise is the smallest as the optimal value of the current key influencing parameter.

[0146] The present application also provides a computer-readable medium, which stores instructions. When the instructions are executed by a processor, the processor executes the steps in the parameter optimization method for suppressing transient overvoltages in new energy AC / DC transmission systems as described in the above embodiments. In practical applications, the computer-readable medium may be included in the device / apparatus / system described in the above embodiments, or may exist independently without being assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs. When the one or more programs are executed, the system is implemented according to the reference. Figure 5 The described method for performing parameter optimization on a parameter optimization device for suppressing transient overvoltage in a new energy AC / DC transmission system.

[0147] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in the description may be different and are not limited. Therefore, those skilled in the art in the field of the present invention may modify or replace the technical solutions recorded in the above embodiments; and these modifications and replacements do not deviate from the creative purpose and technical solutions of the present invention and should all fall within the protection scope of the present invention.

Claims

1. A parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system, characterized in that: The method includes: Determine the controllable parameter combination of the new energy AC / DC transmission system; Construct different value schemes for the combination of controllable parameters; simulate the operation of the new energy AC / DC transmission system under each value scheme, obtain the transient voltage rise of the system after the fault corresponding to the current value scheme, and determine the sensitivity of the system transient voltage rise to the controllable parameters. According to the sensitivity determination results of all value schemes, identify the controllable parameters that affect the system transient voltage rise as the key influencing parameters of the system transient overvoltage; With the goal of minimizing transient voltage rise, the key influencing parameters are optimized.

2. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 1, characterized in that: The optimization of the key influencing parameters with the goal of minimizing the transient voltage rise is as follows: analyzing the interaction between the key influencing parameters based on cosine similarity; when it is determined that there is interaction between the key influencing parameters, the identified key influencing parameters have room for optimization, and the key influencing parameters are optimized using an intelligent optimization algorithm; otherwise, for each key influencing parameter, other parameters are controlled unchanged, and the influence of the current key influencing parameters on the transient voltage rise is obtained through simulation, and the parameter value when the transient voltage rise is minimized is used as the optimal value of the current key influencing parameter, and this process ends.

3. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 2, characterized in that: The interaction between the key influencing parameters based on the cosine similarity analysis is: For the i-th parameter y among the key influencing parameters i , fix the values ​​of other key influencing parameters, and obtain the transient voltage rise of the system with parameter y i The curve of the change; changing the value of the remaining key influencing parameters to obtain multiple curves; calculating the cosine similarity between the curves, and judging whether the cosine similarity is greater than the set similarity threshold, if so, judging the remaining key influencing parameters on the parameter y i There is an interaction relationship; otherwise, it is determined that there is no interaction relationship; If each key influencing parameter does not interact with the other key influencing parameters, it is determined that there is no interaction between the key influencing parameters; as long as any key influencing parameter interacts with the other key influencing parameters, it is determined that there is room for optimization for each key influencing parameter.

4. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 1, characterized in that: The system fault is a DC commutation failure fault; the system transient voltage rise calculation formula is as follows: ΔU=U max -U0 Among them, ΔU is the transient voltage rise of the system after the fault, U max is the maximum value of the system transient overvoltage after the fault, and U0 is the initial value of the system voltage before the fault occurs.

5. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 1, characterized in that: The controllable parameter combination includes: the active current percentage I of the wind turbine during low voltage ride-through p , Active power recovery rate v p and reactive power adjustment coefficient; the minimum interpolation current command, start voltage and exit voltage of the low voltage current limiting control VDCOL link; the proportional gain and integral time constant T of the current control amplifier CCA link on the DC rectifier side i_CCA .

6. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 1, characterized in that: The operation of the new energy AC / DC transmission system is simulated to obtain the transient voltage rise of the system after the fault corresponding to the current value scheme: Use the power system electromechanical transient simulation tool to build a simulation model of the new energy AC / DC transmission system, set the DC commutation failure fault, and obtain the simulation results of the system voltage curve after the fault; The programming software is used to modify the values ​​of controllable parameters in the electromechanical transient simulation tool. The system voltage curve is simulated by the electromechanical transient simulation tool. The programming tool reads the system voltage curve and calculates the system transient voltage rise.

7. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 1, characterized in that: The sensitivity of the system transient voltage rise to the controllable parameters is determined according to the sensitivity determination results of all value-taking schemes, and the controllable parameters affecting the system transient voltage rise are identified as key influencing parameters of the system transient overvoltage, specifically: For each value scheme: increase the value of each controllable parameter at the same percentage at the same time, and obtain the system transient voltage rise ΔU after the controllable parameter value is increased + ; Reduce the value of each controllable parameter by the same percentage at the same time, and obtain the transient voltage rise ΔU of the system after the controllable parameter is reduced - ; Using ΔU + and ΔU - Calculate the sensitivity coefficient of each controllable parameter; Under each value selection scheme, all controllable parameters are sorted according to the sensitivity coefficient of each controllable parameter, and the frequency of each controllable parameter ranking in the top n positions of the setting is counted. The m controllable parameters with the highest frequency are taken as the key influencing parameters of the system transient overvoltage identified; Among them, the value of m is greater than or equal to 3 and less than the number of controllable parameters in the controllable parameter combination; the value of n is 30% to 50% of the number of controllable parameters in the controllable parameter combination, and n is greater than or equal to 3.

8. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 2, characterized in that: The method of optimizing the key influencing parameters by using an intelligent optimization algorithm includes: optimizing the values ​​of the key influencing parameters by using a particle swarm algorithm to minimize the transient voltage rise.

9. The parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system according to any one of claims 1 to 8, characterized in that: The system transient voltage rise adopts one or a weighted sum of the transient voltage rise of the DC sending end bus of the new energy AC / DC transmission system and the transient voltage rise of the fan end bus.

10. A parameter optimization device for suppressing transient overvoltage in a new energy AC / DC transmission system, characterized in that: It includes a controllable parameter combination determination module, a key influencing parameter identification module, and an optimization module; The controllable parameter combination determination module is used to determine the controllable parameter combination of the new energy AC / DC transmission system; The key influencing parameter identification module is used to construct different value schemes for the controllable parameter combination; under each value scheme, the operation of the new energy AC / DC transmission system is simulated to obtain the transient voltage rise of the system after the fault corresponding to the current value scheme, and determine the sensitivity of the system transient voltage rise to the controllable parameters, and identify the controllable parameters that affect the system transient voltage rise according to the sensitivity determination results of all value schemes as the key influencing parameters of the system transient overvoltage; The optimization module is used to optimize the key influencing parameters identified by the key influencing parameter identification module with the goal of minimizing transient voltage rise.

11. The parameter optimization device for suppressing transient overvoltage in a new energy AC / DC transmission system according to claim 10, characterized in that: The optimization module includes an interaction analysis submodule, a first optimization submodule, and a second optimization submodule; The interaction analysis submodule is used to analyze the interaction between the key influencing parameters based on cosine similarity; when it is determined that there is interaction between the key influencing parameters, the identified key influencing parameters have optimization space, and the first optimization submodule is notified to work; Otherwise, notify the second optimization submodule to work; The first optimization submodule is used to optimize the key influencing parameters using an intelligent optimization algorithm; The second optimization submodule is used to control other parameters unchanged for each key influencing parameter, obtain the influence of the current key influencing parameter on the transient voltage rise through simulation, and take the parameter value when the transient voltage rise is the smallest as the optimal value of the current key influencing parameter.

12. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the instructions are executed by the processor, the steps in the parameter optimization method for suppressing transient overvoltage in a new energy AC / DC transmission system as described in any one of claims 1 to 9 can be implemented.

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