Transient voltage safety emergency control method and device

Abstract

The application discloses a transient voltage safety emergency control method, comprising the following steps: according to a first control model, adjusting system terminal voltage reference value and capacitance of a capacitance resistor node, so as to increase bus voltage value; when the bus voltage value reaches a first threshold value, according to a second control model, controlling the variance of reactive power output proportion of each generator to be within a preset range, so as to maintain transient voltage safety. The application divides a transient process into two stages according to the value of bus voltage in the transient process, and through the first control model, the bus voltage is rapidly restored to a relatively high level at the beginning of the transient process, so as to gradually approach the first threshold value; when the bus voltage reaches the first threshold value, through the second control model, the reactive power output of each generator in the system is balanced, so as to avoid that after the transient voltage is stabilized, the reactive power output of the generator is too high, the service life of the generator is affected and the system operation is affected, and the economy of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of transient voltage safety control technology, and in particular to a transient voltage safety emergency control method and device. Background Technology

[0002] Voltage safety and stability are divided into transient voltage safety and medium- to long-term voltage stability. Transient voltage safety refers to the voltage safety and stability within 10 seconds after a fault occurs. System faults can cause a significant drop in the voltage amplitude of some node buses, leading to an increase in the slip rate of induction motor loads and an increased demand for reactive power after the fault. Even after the fault is cleared, it can still cause significant oscillations in bus voltage and problems such as low voltage recovery and delayed recovery. When the load bus voltage falls below the threshold, induction motors may stall, causing a sharp increase in reactive power absorption, further reducing the system bus voltage and potentially leading to system collapse.

[0003] When a fault or disturbance has just been cleared, the primary task of emergency transient voltage control is to ensure the safety of the transient voltage with minimal control overhead. After ensuring the safe operation of the system, the main task of emergency control is to adjust the system's operating status so that it can operate more rationally and economically. On the other hand, as power system managers, we must ensure the safety of transient voltage while also considering the economic efficiency after safe operation. When the system reactive power is sufficient, balancing generator reactive power output should be the primary consideration; when the system reactive power is insufficient and voltage levels are generally low, maintaining the voltage of the dominant node should be the primary consideration. Otherwise, it is easy to reverse the priorities, such as making maintaining the voltage of the dominant node the primary control objective when the voltage level has already met the requirements, which is clearly unreasonable.

[0004] Existing emergency control methods for transient voltage safety adjust the system's operating status by reducing the deviation between the dominant node voltage and the reference value and balancing the reactive power output of each generator in the system to maintain transient voltage safety. However, these methods do not take into account the economic efficiency after the voltage is safely operating, nor do they make timely adjustments to the system. As a result, the system's reactive power is too high, and the system's economic efficiency is low. Summary of the Invention

[0005] This invention provides a transient voltage safety emergency control method and device to solve the technical problem that existing transient voltage safety emergency control methods do not consider the economic efficiency after voltage safety operation, resulting in excessive reactive power and low system economy.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a transient voltage safety emergency control method, comprising:

[0007] Based on the first control model, the reference value of the system terminal voltage and the capacitor at the capacitive reactor node are adjusted to increase the bus voltage value.

[0008] When the bus voltage reaches the first threshold, the variance of the reactive power output ratio of each generator is controlled within a preset range according to the second control model in order to maintain transient voltage safety.

[0009] This invention divides the transient process into two stages based on the bus voltage value during the transient process. At the beginning of the transient process, the system terminal voltage reference value and the capacitor node capacitor of the capacitive reactor are rapidly adjusted through the first control model so that the bus voltage can quickly recover to a relatively high level, thereby gradually approaching the first threshold. When the bus voltage reaches the first threshold, the reactive power output ratio of each generator is controlled within a preset range to balance the reactive power output of each generator in the system. This avoids excessive reactive power output of the generators after the transient voltage stabilizes, which would affect the generator life and system operation, thereby improving the system's economy.

[0010] Furthermore, before adjusting the system terminal voltage reference value and the capacitive reactor node capacitor according to the first control model to increase the bus voltage value, the method further includes:

[0011] The transient process is simulated by time-domain simulation to obtain the numerical changes of the controlled variables after the control variables change; the controlled variables include the generator rotor angle, the bus voltage value, and the generator reactive power output.

[0012] A sensitivity matrix model is established, and a first sensitivity matrix is ​​calculated when the bus voltage value of the transient process is less than a first threshold, and a second sensitivity matrix is ​​calculated when the bus voltage value of the transient process is greater than the first threshold; the sensitivity matrix model includes the linear relationship between the controlled variable and the control variable.

[0013] This invention simulates the transient process in advance through a time-domain simulation, thereby obtaining the numerical change of the controlled quantity after the value of the control variable changes, avoiding multiple time-domain simulations. At the same time, by segmenting the transient process in the time-domain simulation according to the bus voltage, a sensitivity matrix is ​​established to establish the linear relationship between different control variables and controlled quantities at different time periods.

[0014] Furthermore, before adjusting the system terminal voltage reference value and the capacitive reactor node capacitor according to the first control model to increase the bus voltage value, the method further includes:

[0015] Based on the first sensitivity matrix, a first objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0016] Based on the fact that the first control cost of controlling the upper limit of excitation regulation is equal to the second control cost of the upper limit of capacitor switching, a second objective function that minimizes the target control cost is established.

[0017] A first control model is established by combining the first objective function and the second objective function; the first control model includes three constraints.

[0018] This invention establishes a first objective function through a first sensitivity matrix in the first time period to minimize the deviation between the dominant node voltage and the voltage reference value, thereby increasing the bus voltage of the dominant node. Simultaneously, by using a second objective function, the first control cost of controlling the upper limit of excitation regulation is equal to the second control cost of controlling the upper limit of capacitor switching, so that the control quantities of excitation regulation and capacitor switching can be balanced under the same control cost, thereby minimizing the control cost. By combining the two objective functions, a first control model is established, so that in the first stage of control, the bus voltage can be quickly restored to a higher level with a smaller control cost.

[0019] Furthermore, before controlling the variance of the reactive power output ratio of each generator within a preset range according to the second control model when the bus voltage reaches the first threshold, in order to maintain transient voltage safety, the method further includes:

[0020] Based on the second sensitivity matrix, a third objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0021] Based on the sensitivity matrix model, a third sensitivity matrix of reactive power output to control variables is established, and a fourth objective function for balancing the reactive power output of each generator is established based on the third sensitivity matrix.

[0022] A second control model is established by combining the third and fourth objective functions; the second control model includes three constraints.

[0023] This invention establishes a third objective function to minimize the deviation between the dominant node voltage and the voltage reference value through a second sensitivity matrix in the second stage, thereby maintaining transient voltage stability. At the same time, it balances the reactive power output of each generator through a fourth objective function to avoid excessive reactive power output in the system, which would affect system operation and generator lifespan. A second control model is established through the two objective functions to ensure that when the bus voltage of the dominant node tends to stabilize, the reactive power output is within an appropriate range, thus avoiding excessive reactive power output in the system and low system economy.

[0024] Furthermore, according to the first control model, adjusting the system terminal voltage reference value and the capacitor at the capacitive reactor node to increase the bus voltage value specifically involves:

[0025] During the transient process, a dominant node is selected based on the magnitude of the bus voltage drop; and according to the first control model, the system terminal voltage reference value and the capacitor of the capacitive reactor node are adjusted to adjust the bus voltage value of the dominant node until the bus voltage value reaches the first threshold.

[0026] Secondly, embodiments of the present invention provide a transient voltage safety emergency control device, comprising: a first control module and a second control module;

[0027] The first control module is used to adjust the system terminal voltage reference value and the capacitor node capacitor of the capacitive reactor according to the first control model in order to increase the bus voltage value.

[0028] The second control module is used to control the variance of the reactive power output ratio of each generator within a preset range according to the second control model when the bus voltage value reaches the first threshold, so as to maintain transient voltage safety.

[0029] Furthermore, the transient voltage safety emergency control device also includes a sensitivity matrix construction module, specifically used for:

[0030] The transient process is simulated by time-domain simulation to obtain the numerical changes of the controlled variables after the control variables change; the controlled variables include the generator rotor angle, the bus voltage value, and the generator reactive power output.

[0031] A sensitivity matrix model is established, and a first sensitivity matrix is ​​calculated when the bus voltage value of the transient process is less than a first threshold, and a second sensitivity matrix is ​​calculated when the bus voltage value of the transient process is greater than the first threshold; the sensitivity matrix model includes the linear relationship between the controlled variable and the control variable.

[0032] Furthermore, the sensitivity matrix construction module is also used for:

[0033] Based on the first sensitivity matrix, a first objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0034] Based on the fact that the first control cost of controlling the upper limit of excitation regulation is equal to the second control cost of the upper limit of capacitor switching, a second objective function that minimizes the target control cost is established.

[0035] A first control model is established by combining the first objective function and the second objective function; the first control model includes three constraints.

[0036] Furthermore, the sensitivity matrix construction module is also used for:

[0037] Based on the second sensitivity matrix, a third objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0038] Based on the sensitivity matrix model, a third sensitivity matrix of reactive power output to control variables is established, and a fourth objective function for balancing the reactive power output of each generator is established based on the third sensitivity matrix.

[0039] A second control model is established by combining the third and fourth objective functions; the second control model includes three constraints.

[0040] Furthermore, the first control module is specifically used for:

[0041] During the transient process, a dominant node is selected based on the magnitude of the bus voltage drop; and according to the first control model, the system terminal voltage reference value and the capacitor of the capacitive reactor node are adjusted to adjust the bus voltage value of the dominant node until the bus voltage value reaches the first threshold. Attached Figure Description

[0042] Figure 1 A schematic flowchart of a transient voltage safety emergency control method provided in an embodiment of the present invention;

[0043] Figure 2 This is an ideal voltage recovery curve for the transient voltage safety emergency control method provided in the embodiments of the present invention.

[0044] Figure 3 This is a schematic diagram of a transient voltage safety emergency control device provided in an embodiment of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example 1

[0047] Please refer to Figure 1 , Figure 1 A flowchart illustrating a transient voltage safety emergency control method provided in an embodiment of the present invention includes steps 101 to 102, as detailed below:

[0048] Step 101: Based on the first control model, adjust the system terminal voltage reference value and the capacitor at the capacitive reactor node to increase the bus voltage value;

[0049] In this embodiment, before adjusting the system terminal voltage reference value and the capacitive reactor node capacitor according to the first control model to increase the bus voltage value, the method further includes:

[0050] The transient process is simulated by time-domain simulation to obtain the numerical changes of the controlled variables after the control variables change; the controlled variables include the generator rotor angle, the bus voltage value, and the generator reactive power output.

[0051] A sensitivity matrix model is established, and a first sensitivity matrix is ​​calculated when the bus voltage value of the transient process is less than a first threshold, and a second sensitivity matrix is ​​calculated when the bus voltage value of the transient process is greater than the first threshold; the sensitivity matrix model includes the linear relationship between the controlled variable and the control variable.

[0052] In this embodiment, trajectory sensitivity is used to locally linearize each point on the system's trajectory, and the sensitivity matrix model is used to describe the changes in the system's trajectory when parameters undergo small changes. A sensitivity matrix model is established using trajectory sensitivity, and the functional relationship between the control variables and the desired state variables and algebraic variables is approximately linearized based on this model. Based on this, the change in the system state after control is applied is calculated.

[0053] In this embodiment, let the increment of the control variable be Δu, the increment of the controlled variable be ΔV, and the sensitivity matrix model of the controlled variable V relative to the control variable u be C. v Then, the linear relationship between the increment of the controlled variable, the increment of the control variable, and the sensitivity matrix model can be expressed as:

[0054] ΔV=C v ·Δu (1)

[0055] In this embodiment, the behavior of the power system during transient processes can be obtained by solving the following system of nonlinear differential-algebraic equations:

[0056]

[0057] By simultaneously taking the partial derivative of the control variable u with respect to formula (2):

[0058]

[0059] Where x is a vector of state variables such as generator rotor angle, y is a vector of algebraic variables such as bus node voltage magnitude and phase angle, and u is a vector of control variables. u and y u Take the partial derivatives of the state variable vector x and the algebraic variable vector y with respect to the control variable u, respectively, and f x f y f u and g x gy g u These represent the results of taking the partial derivatives of the differential equation and the algebraic equation with respect to x, y, and u, respectively. x and y can be obtained by calculating the system state values ​​of the trajectory points.

[0060] In this embodiment, the system's state variable x does not undergo abrupt changes during the transient process. At the moment the system is put under control, x... u initial value We can consider it as 0, and then we can find y using the second equation in formula 3. u initial value

[0061] In this embodiment, formula 3 is solved using the implicit trapezoidal integral method, as follows:

[0062]

[0063] Where t and t+1 represent the t-th and t+1-th steps of integration, respectively, and h represents the integration step size of the t-th step.

[0064] In this embodiment, time-domain simulation calculations are performed using Power System Analysis Toolbox (PSAT), a software developed based on Matlab. At each calculation time step, matrix f is generated. x f y g x g y After obtaining the initial value and Subsequently, x can be obtained step by step according to equation (4). u and y u The magnitude of the value that changes over time, while x u and y u This is the sensitivity matrix of the state variable x and the algebraic variable y to the control variable u.

[0065] In this embodiment, a transient process is simulated in the time domain beforehand to obtain the sensitivity trajectory, thus obtaining the numerical change of the controlled variable after the control variable value changes, avoiding multiple time domain simulations. This is achieved through the sensitivity matrix model C. v This allows us to calculate the increment ΔV of the controlled variable based on the increment of the control variable, thereby obtaining the sensitivity matrix of the controlled variable to the control variable.

[0066] In this embodiment, the transient process in the time-domain simulation is divided into two stages based on the bus voltage value, and the first and second sensitivity matrices of the controlled variable with respect to the control variable are calculated for each stage. The controlled variable is the master node voltage vector V. p0 .

[0067] In this embodiment, before adjusting the system terminal voltage reference value and the capacitive reactor node capacitor according to the first control model to increase the bus voltage value, the method further includes:

[0068] Based on the first sensitivity matrix, a first objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0069] Based on the fact that the first control cost of controlling the upper limit of excitation regulation is equal to the second control cost of the upper limit of capacitor switching, a second objective function that minimizes the target control cost is established.

[0070] A first control model is established by combining the first objective function and the second objective function; the first control model includes three constraints.

[0071] In this embodiment, the present invention simulates the transient process in advance by performing a time-domain simulation, thereby obtaining the numerical change of the controlled quantity after the value of the control variable changes, thus avoiding multiple time-domain simulations. At the same time, by segmenting the transient process in the time-domain simulation according to the bus voltage, a sensitivity matrix is ​​established to establish a linear relationship between different control variables and controlled quantities at different time periods.

[0072] In this embodiment, the transient voltage is divided into two stages based on the bus voltage value. In the first stage, the amplitude deviation of the dominant node bus voltage and the control cost are minimized to ensure that the transient voltage recovers quickly and stably after the fault is cleared. In the second stage, the variance of the amplitude deviation of the dominant node bus voltage and the proportion of generator reactive power output is minimized to ensure that the system economy is improved when the bus voltage is at a higher level.

[0073] In this embodiment, the goal in Phase 1 is to minimize the deviation between the dominant node voltage and the voltage reference value to ensure that the dominant node voltage can quickly recover to a higher level. Since the system's state changes drastically during transient processes, the voltage amplitude may fluctuate significantly over a certain period. Measuring the voltage deviation solely at a single point in time is insufficient. Therefore, it is necessary to integrate the square of the voltage deviation over a period after fault clearance and control activation, thereby establishing a first objective function that minimizes the deviation between the dominant node voltage and the voltage reference value using the first sensitivity matrix.

[0074] In this embodiment, the fault clearing time t is taken. c The control process within 5 seconds is considered Phase 1. At this point, the system has just experienced a short-circuit fault and line disconnection, and the system bus voltage is generally at a low level (typically below 0.7 pu). By implementing control, the bus voltage value is restored to the first threshold value within 5 seconds. Therefore, the first objective function is specifically:

[0075]

[0076] Among them, V p0 C represents the dominant node voltage vector before control is implemented. p The dominant node voltage vector V p0 The sensitivity matrix for the control variable u, where Δu is the increment of the control variable, V gref Let [t] be the reference voltage vector, and the integration interval is [t]. c ,5],t c To allow for control of the time invested.

[0077] Please refer to Figure 2 , Figure 2 This is an ideal voltage recovery curve for the transient voltage safety emergency control method provided in the embodiments of the present invention.

[0078] In this embodiment, after control is initiated, the voltage amplitude of the dominant node can typically recover from a lower value to a relatively higher level. During this process, the voltage amplitude changes significantly, and ideally, it can rise exponentially, gradually approaching a certain steady-state value.

[0079] Therefore, the reference voltage V in this stage gref It should also be set to Figure 2 The reference voltage is set using the following formula, which illustrates the exponentially increasing form:

[0080] V pref =V prefend -xe -t (6)

[0081] Among them, V gref end Here, x represents the steady-state voltage amplitude, and x is an adjustment coefficient used to ensure the reference voltage V at the control activation time t. gref The value is equal to the control voltage V at that moment. p0 This means ensuring that the voltage does not change abruptly when control is applied.

[0082] Furthermore, in Phase 1, a second objective function is established to minimize the control cost while ensuring transient voltage safety. The specific formula for the second objective function is as follows:

[0083]

[0084] Where Δu i and Δu j n1 and n2 correspond to the excitation voltage reference value adjustment and the capacitor switching amount of the capacitive reactor node, respectively, and the number of corresponding control variables. α and β are the weighting coefficients of the corresponding control variables.

[0085] In this embodiment, in power system stability control, the generator excitation adjustment range Δu i max The adjustment range of capacitor switching is smaller than that of capacitor switching, and because excitation regulation is a valuable control resource for the system, its control cost is also greater than that of capacitor switching. This paper takes β as the baseline 1, then α is specifically:

[0086]

[0087] Where, Δu i max and Δu j max These refer to the range of excitation regulation and the range of capacitor switching, respectively. Formula 8 can be used to ensure that the control cost of the upper limit of excitation regulation is equal to the control cost of the upper limit of capacitor switching, thus balancing the control amounts of excitation regulation and capacitor switching under the same control cost.

[0088] In this embodiment, the dominant node bus voltage V is made so by the first objective function. p With voltage reference value V pref To minimize the control cost, the second objective function is used to balance the control quantities of excitation regulation and capacitor switching, thus minimizing the control cost. A first control model is constructed by combining the first and second objective functions. This allows, in stage one, the dominant node voltage to be artificially guided towards an ideal direction by setting a reasonable voltage reference value, thereby ensuring transient voltage stability. The acceptability of transient voltage drops can be guaranteed by ensuring that the dominant node bus voltage recovers to above 0.75 pu within 1 second after fault clearance. Therefore, the first control model is specifically as follows:

[0089]

[0090] The first constraint is to control the voltage of the dominant node bus, and the second constraint is to ensure that the voltage of the dominant node does not exceed its upper and lower limits during the control process. pmax V pmin These correspond to their upper and lower limits, respectively; the third constraint condition is to ensure that the increment of the control variable does not exceed its upper and lower limits, where Δu imax , Δu imin These are the upper and lower limits of the corresponding control variable increments.

[0091] In this embodiment, a first objective function is established using the first sensitivity matrix of the first time period to minimize the deviation between the dominant node voltage and the voltage reference value, thereby increasing the bus voltage of the dominant node. Simultaneously, a second objective function is used to ensure that the first control cost of the upper limit of excitation regulation is equal to the second control cost of the upper limit of capacitor switching, so that the control quantities of excitation regulation and capacitor switching can be balanced under the same control cost, thereby minimizing the control cost. By combining the two objective functions, a first control model is established, so that in the first stage of control, the bus voltage can be quickly restored to a higher level with a smaller control cost.

[0092] Step 102: Based on the first control model, adjust the system terminal voltage reference value and the capacitor at the capacitive reactor node to increase the bus voltage value;

[0093] In this embodiment, before controlling the variance of the reactive power output ratio of each generator within a preset range according to the second control model to maintain transient voltage safety when the bus voltage value reaches the first threshold, the method further includes:

[0094] Based on the second sensitivity matrix, a third objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0095] Based on the sensitivity matrix model, a third sensitivity matrix of reactive power output to control variables is established, and a fourth objective function for balancing the reactive power output of each generator is established based on the third sensitivity matrix.

[0096] A second control model is established by combining the third and fourth objective functions; the second control model includes three constraints.

[0097] In this embodiment, during the second stage of the transient voltage, the second sensitivity matrix C established through time-domain simulation... p Obtain the dominant node voltage vector V p0 Based on the linear relationship of the control variable u, a third objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value. Specifically, the third objective function is:

[0098]

[0099] Among them, V p0 C represents the dominant node voltage vector before control is implemented. p The dominant node voltage V p The trajectory sensitivity matrix for the control variable u, where Δu is the increment of the control variable, V pref The reference voltage vector can be used. Since the state change in the second stage is relatively small, the reference voltage V can be used as the reference voltage vector. prefSet to a constant value (1.0 or 1.05 pu).

[0100] In this embodiment, considering the economic efficiency of system operation, it is necessary to obtain the reactive power output Q based on the sensitivity matrix model. gi The linear relationship of the control variable u is used to establish a third sensitivity matrix. Based on this third sensitivity matrix, a fourth objective function is constructed to balance the reactive power output of each generator.

[0101] In this embodiment, since the variance of the reactive power output ratio of the generator can be used to measure whether the reactive power output of the generator is uniform, the specific proportion of reactive power output of each generator is as follows:

[0102]

[0103] Where, n g Q represents the number of generators in the system. gi Q corresponds to the reactive power output of the i-th generator before control. gimax Q gimin This corresponds to the maximum and minimum reactive power output. C q Q for doing nothing gi The trajectory sensitivity matrix for the control variable u.

[0104] In this embodiment, the fourth objective function can be defined as the integral of the variance of the reactive power output ratio over time, specifically:

[0105]

[0106] in, This represents the average proportion of reactive power output.

[0107] In this embodiment, a third objective function is used to maintain transient voltage stability, and a fourth objective function is used to control the reactive power output of each generator to ensure uniform reactive power output. A second control model is established by combining the third and fourth objective functions to ensure the most uniform reactive power output of the generators under transient voltage safety conditions, thereby improving the system's economy. The second control model is specifically as follows:

[0108]

[0109] Among them, the three constraints correspond to the dominant node and the point voltage V, respectively. p Within its upper and lower limits, the generator reactive power output Q g Within its upper and lower limits, the increment of the control variable Δu is within its upper and lower limits.

[0110] In this embodiment, a third objective function is established through the second sensitivity matrix of the second stage to minimize the deviation between the dominant node voltage and the voltage reference value, thereby maintaining transient voltage stability. At the same time, a fourth objective function is used to balance the reactive power output of each generator to avoid excessive reactive power output in the system, which would affect system operation and generator lifespan. A second control model is established through the two objective functions to ensure that when the bus voltage of the dominant node tends to stabilize, the reactive power output is within an appropriate range, thus avoiding excessive reactive power output in the system and low system economy.

[0111] In this embodiment, adjusting the system terminal voltage reference value and the capacitor at the capacitive reactor node according to the first control model to increase the bus voltage value specifically involves:

[0112] During the transient process, a dominant node is selected based on the magnitude of the bus voltage drop; and according to the first control model, the system terminal voltage reference value and the capacitor of the capacitive reactor node are adjusted to adjust the bus voltage value of the dominant node until the bus voltage value reaches the first threshold.

[0113] In this embodiment, starting from the fault clearing time, the node with the most severe bus voltage drop during the transient process is selected as the dominant node. If the voltage of the dominant node is within an acceptable range, then the voltages of other load nodes in the system can be considered to be within an acceptable deviation range. Therefore, the adjustment amount ΔV of the generator AVR terminal voltage reference value is quickly adjusted using the first control model. gref And the switching amount Δb of the capacitor at the capacitive reactor node, to adjust the bus voltage value of the dominant node until the bus voltage value increases to a first threshold.

[0114] In this embodiment, the faulty node is selected as the dominant node, and the first threshold is set to 0.9 pu.

[0115] In this embodiment, when the bus voltage reaches the first threshold, the dominant node voltage deviation and the required control input will not be significant. At this time, the adjustment amount ΔV of the generator AVR terminal voltage reference value is adjusted according to the second control model. gref In addition, the switching amount Δb of the capacitors at the capacitor nodes limits the possible overvoltage and balances the reactive power output of each generator, making the system's operating state closer to a steady-state operating state.

[0116] Please refer to Figure 3 , Figure 3 A schematic diagram of a transient voltage safety emergency control device provided in an embodiment of the present invention includes a first control module 301 and a second control module 302.

[0117] The first control module 301 is used to adjust the system terminal voltage reference value and the capacitor node capacitor of the capacitive reactor according to the first control model in order to increase the bus voltage value.

[0118] The second control module 302 is used to control the variance of the reactive power output ratio of each generator within a preset range according to the second control model when the bus voltage value reaches the first threshold, so as to maintain transient voltage safety.

[0119] In this embodiment, the transient voltage safety emergency control device further includes a sensitivity matrix construction module, specifically used for:

[0120] The transient process is simulated by time-domain simulation to obtain the numerical changes of the controlled variables after the control variables change; the controlled variables include the generator rotor angle, the bus voltage value, and the generator reactive power output.

[0121] A sensitivity matrix model is established, and a first sensitivity matrix is ​​calculated when the bus voltage value of the transient process is less than a first threshold, and a second sensitivity matrix is ​​calculated when the bus voltage value of the transient process is greater than the first threshold; the sensitivity matrix model includes the linear relationship between the controlled variable and the control variable.

[0122] In this embodiment, the sensitivity matrix construction module is further used for:

[0123] Based on the first sensitivity matrix, a first objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0124] Based on the fact that the first control cost of controlling the upper limit of excitation regulation is equal to the second control cost of the upper limit of capacitor switching, a second objective function that minimizes the target control cost is established.

[0125] A first control model is established by combining the first objective function and the second objective function; the first control model includes three constraints.

[0126] In this embodiment, the sensitivity matrix construction module is further used for:

[0127] Based on the second sensitivity matrix, a third objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value.

[0128] Based on the sensitivity matrix model, a third sensitivity matrix of reactive power output to control variables is established, and a fourth objective function for balancing the reactive power output of each generator is established based on the third sensitivity matrix.

[0129] A second control model is established by combining the third and fourth objective functions; the second control model includes three constraints.

[0130] In this embodiment, the first control module is specifically used for:

[0131] During the transient process, a dominant node is selected based on the magnitude of the bus voltage drop; and according to the first control model, the system terminal voltage reference value and the capacitor of the capacitive reactor node are adjusted to adjust the bus voltage value of the dominant node until the bus voltage value reaches the first threshold.

[0132] In this embodiment, the transient process is divided into two stages based on the bus voltage value during the transient process. At the beginning of the transient process, the system terminal voltage reference value and the capacitor node capacitor of the capacitive reactor are quickly adjusted through the first control model so that the bus voltage can be quickly restored to a relatively high level, thereby gradually approaching the first threshold. When the bus voltage reaches the first threshold, the reactive power output ratio of each generator is controlled within a preset range to balance the reactive power output of each generator in the system. This avoids excessive reactive power output of the generators after the transient voltage stabilizes, which would affect the generator life and system operation, thereby improving the system's economy.

[0133] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A transient voltage safety emergency control method, characterized in that, include: Based on the first control model, the reference value of the system terminal voltage and the capacitor at the capacitive reactor node are adjusted to increase the bus voltage value. The first control model is established by a first objective function and a second objective function; the first objective function is used to minimize the deviation between the dominant node voltage and the voltage reference value according to the first sensitivity matrix; the second objective function is used to make the first control cost for controlling the upper limit of excitation regulation equal to the second control cost for controlling the upper limit of capacitor switching. The first sensitivity matrix is ​​calculated based on the sensitivity matrix model when the bus voltage value during the transient process is less than the first threshold. The sensitivity matrix model includes the linear relationship between the controlled quantity and the control variable; The first control cost is the cost incurred by the generator when performing excitation regulation; the second control cost is the cost incurred by controlling the switching of capacitors. When the bus voltage reaches the first threshold, according to the second control model, the variance of the reactive power output ratio of each generator is controlled within a preset range to maintain transient voltage safety. The second control model is established by a third objective function and a fourth objective function. The third objective function is used to minimize the deviation between the dominant node voltage and the voltage reference value according to the second sensitivity matrix. The fourth objective function is used to balance the reactive power output of each generator according to the third sensitivity matrix. The second sensitivity matrix is ​​calculated based on the sensitivity matrix model when the bus voltage is greater than or equal to the first threshold during the transient process. The third sensitivity matrix is ​​constructed based on the linear relationship between reactive power output and control variables.

2. The transient voltage safety emergency control method as described in claim 1, characterized in that, Before adjusting the system terminal voltage reference value and the capacitive reactor node capacitor according to the first control model to increase the bus voltage value, the method further includes: The transient process is simulated by time-domain simulation to obtain the numerical changes of the controlled variables after the control variables change; the controlled variables include the generator rotor angle, the bus voltage value, and the generator reactive power output. A sensitivity matrix model is established, and a first sensitivity matrix is ​​calculated when the bus voltage value of the transient process is less than a first threshold, and a second sensitivity matrix is ​​calculated when the bus voltage value of the transient process is greater than the first threshold; the sensitivity matrix model includes the linear relationship between the controlled variable and the control variable.

3. The transient voltage safety emergency control method as described in claim 2, characterized in that, Before adjusting the system terminal voltage reference value and the capacitive reactor node capacitor according to the first control model to increase the bus voltage value, the method further includes: Based on the first sensitivity matrix, a first objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value. Based on the fact that the first control cost of controlling the upper limit of excitation regulation is equal to the second control cost of the upper limit of capacitor switching, a second objective function that minimizes the target control cost is established. A first control model is established by combining the first objective function and the second objective function; the first control model includes three constraints.

4. The transient voltage safety emergency control method as described in claim 2, characterized in that, Before controlling the variance of the reactive power output ratio of each generator within a preset range according to the second control model when the bus voltage reaches the first threshold, in order to maintain transient voltage safety, the method further includes: Based on the second sensitivity matrix, a third objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value. Based on the sensitivity matrix model, a third sensitivity matrix of reactive power output to control variables is established, and a fourth objective function for balancing the reactive power output of each generator is established based on the third sensitivity matrix. A second control model is established by combining the third and fourth objective functions; the second control model includes three constraints.

5. The transient voltage safety emergency control method as described in claim 1, characterized in that, The step of adjusting the system terminal voltage reference value and the capacitor at the capacitive reactor node according to the first control model to increase the bus voltage value is as follows: During the transient process, a dominant node is selected based on the magnitude of the bus voltage drop; and according to the first control model, the system terminal voltage reference value and the capacitor of the capacitive reactor node are adjusted to adjust the bus voltage value of the dominant node until the bus voltage value reaches the first threshold.

6. A transient voltage safety emergency control device, characterized in that, include: First control module and second control module; The first control module is used to adjust the system terminal voltage reference value and the capacitor node capacitor of the capacitive reactor according to the first control model in order to increase the bus voltage value. The first control model is established by a first objective function and a second objective function; the first objective function is used to minimize the deviation between the dominant node voltage and the voltage reference value according to the first sensitivity matrix; the second objective function is used to make the first control cost for controlling the upper limit of excitation regulation equal to the second control cost for controlling the upper limit of capacitor switching. The first sensitivity matrix is ​​calculated based on the sensitivity matrix model when the bus voltage value during the transient process is less than the first threshold. The sensitivity matrix model includes the linear relationship between the controlled quantity and the control variable; The first control cost is the cost incurred by the generator when performing excitation regulation; The second control cost is the cost incurred in controlling the switching of capacitors; The second control module is used to control the variance of the reactive power output ratio of each generator within a preset range according to the second control model when the bus voltage value reaches the first threshold, so as to maintain transient voltage safety. The second control model is established by a third objective function and a fourth objective function. The third objective function is used to minimize the deviation between the dominant node voltage and the voltage reference value according to the second sensitivity matrix. The fourth objective function is used to balance the reactive power output of each generator according to the third sensitivity matrix. The second sensitivity matrix is ​​calculated based on the sensitivity matrix model when the bus voltage value in the transient process is greater than or equal to the first threshold. The third sensitivity matrix is ​​constructed based on the linear relationship between reactive power output and control variables.

7. The transient voltage safety emergency control device as described in claim 6, characterized in that, The transient voltage safety emergency control device also includes a sensitivity matrix construction module, specifically used for: The transient process is simulated by time-domain simulation to obtain the numerical changes of the controlled variables after the control variables change; the controlled variables include the generator rotor angle, the bus voltage value, and the generator reactive power output. A sensitivity matrix model is established, and a first sensitivity matrix is ​​calculated when the bus voltage value of the transient process is less than a first threshold, and a second sensitivity matrix is ​​calculated when the bus voltage value of the transient process is greater than the first threshold; the sensitivity matrix model includes the linear relationship between the controlled variable and the control variable.

8. The transient voltage safety emergency control device as described in claim 7, characterized in that, The sensitivity matrix construction module is also used for: Based on the first sensitivity matrix, a first objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value. Based on the fact that the first control cost of controlling the upper limit of excitation regulation is equal to the second control cost of the upper limit of capacitor switching, a second objective function that minimizes the target control cost is established. A first control model is established by combining the first objective function and the second objective function; the first control model includes three constraints.

9. The transient voltage safety emergency control device as described in claim 7, characterized in that, The sensitivity matrix construction module is also used for: Based on the second sensitivity matrix, a third objective function is established to minimize the deviation between the dominant node voltage and the voltage reference value. Based on the sensitivity matrix model, a third sensitivity matrix of reactive power output to control variables is established, and a fourth objective function for balancing the reactive power output of each generator is established based on the third sensitivity matrix. A second control model is established by combining the third and fourth objective functions; the second control model includes three constraints.

10. The transient voltage safety emergency control device as described in claim 6, characterized in that, The first control module is specifically used for: During the transient process, a dominant node is selected based on the magnitude of the bus voltage drop; and according to the first control model, the system terminal voltage reference value and the capacitor of the capacitive reactor node are adjusted to adjust the bus voltage value of the dominant node until the bus voltage value reaches the first threshold.

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