An emergency reactive power control method, system, device and storage medium suitable for node voltage instability

Abstract

The present invention discloses an emergency reactive power control method, system, device, and storage medium suitable for node voltage instability. The method is based on offline simulation of an N-2 AC fault in the power grid, obtains the voltage value and slip of the load node under different voltage drop levels at the time of emergency control action, compares them with the critical voltage value and critical slip value of the load node, and calculates the amount of emergency control measures; triggers emergency control through the power grid fault, promptly matches the interval where the fault voltage drop value is located, and obtains the amount of emergency control measures; when the load node voltage is greater than or equal to the emergency control exit threshold, gradually exits the reactive power invested during the emergency control period. The present invention comprehensively considers the different severity levels of the fault and the different operating states of the induction motor, calculates different amounts of emergency control measures, and efficiently utilizes the dynamic reactive power resources near the node, which can effectively suppress the voltage instability of the load node and improve the voltage stability of the power system.

Description

Technical Field

[0001] The present invention relates to power systems and automation technologies thereof, and in particular to an emergency reactive power control method, system, device and storage medium applicable to node voltage instability. Background Art

[0002] As the scale of power grid construction continues to expand, the load on the power system is increasing. The greater the proportion of dynamic and nonlinear loads, the less reactive power support capacity, and the more likely grid voltage instability will occur. As one of the key loads in urban power grids, the load characteristics of induction motors are closely related to the voltage stability of the power system and are particularly important to grid security. The balance between the electromagnetic power and mechanical power of induction motors affects the variation trend of slip. If a system fault causes the bus voltage at the load node to drop, the electromagnetic power of the induction motor will rapidly decrease, and the slip will increase. If the critical stability state cannot be reached in time, the system will experience irreversible voltage instability and even cause voltage collapse. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide an emergency reactive power control method, system, device and storage medium suitable for node voltage instability, which can suppress load node voltage instability, prevent grid voltage collapse, and efficiently utilize dynamic reactive power resources near the load node.

[0004] Technical solution: The present invention provides an emergency reactive power control method applicable to node voltage instability, comprising:

[0005] Scan the grid N-2 AC anticipated faults and identify all faults that cause node voltage instability as fault trigger set A i , where i = 1, 2, 3, ...;

[0006] Obtain fault trigger set A through offline simulation i The instantaneous voltage value u of the fault node under different voltage drop degrees of each fault i,fault,x and the voltage value u at the time of emergency control action of the load node i,x , slip value s i,x ; Combined with the load operating parameters, calculate the fault trigger set A i Critical voltage value u of medium load node i,cri and critical slip value s i,cri ; According to the voltage value u i,x , slip value s i,x and critical voltage u i,cri , critical slip value s i,cri Size, calculate the minimum target voltage value u of the load node target,i,x , and then calculate the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each faulti,x ;

[0007] When a power grid fault is detected, the triggering set A i When a fault occurs, the emergency control is started to obtain the instantaneous voltage value u of the fault node. i,fault , matching the instantaneous voltage value u of the fault node i,fault The voltage range [u i,fault,n ,u i,fault,n+1 ], the minimum value u of the fault node voltage interval is applied to the load node i,fault,n The corresponding emergency control measures quantity Q i,n ;

[0008] When the load node bus voltage u is detected m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually exit the reactive power invested during the emergency control period until all are exited and the emergency control strategy ends.

[0009] Furthermore, the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x , the calculation process is as follows:

[0010] Set the voltage drop step size and scan the fault trigger set A separately i For the different severity of the same fault, record the instantaneous voltage value of the fault node, and count them in order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and record the voltage value u of the load node at the time of emergency control action. i,x , slip value s i,x ;

[0011] According to the electromagnetic power characteristic equation of the induction motor load P ei (u,s) and mechanical power P mi (s), calculate the tangent point of the two characteristic curves (u i,cri ,s i,cri ), and the critical voltage value u of the load node is obtained i,cri and critical slip value s i,cri ;

[0012] Compare the slip value s at the moment of emergency control action of the load node i,x Critical slip value s of the load node i,cri The size of s i,x i,cri , then u target,i,x =u i,cri ; If s i,x ≥s​i,cri , then calculate the electromagnetic power characteristic equation of the induction motor P ei (u,s) and mechanical power characteristic equation P mi (s) When the slip value is equal to s i,x The intersection point when the voltage at the intersection point is taken as the minimum target voltage value u target,i,x ;

[0013] According to the voltage value u at the time of emergency control action of the load node i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures Q i,x .

[0014] Furthermore, the tangent point (u i,cri ,s i,cri ), which is calculated as follows:

[0015]

[0016] Among them, R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K Li is the load factor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load; the equivalent resistance of the induction motor load R ei and reactance X ei The calculation formula is as follows:

[0017]

[0018] Among them, X mi is the magnetizing reactance of the induction motor load; R si is the stator resistance of the induction motor load; X si is the stator reactance of the induction motor load; j is a complex unit.

[0019] Furthermore, the minimum target voltage value u target,i,x , which is calculated as follows:

[0020]

[0021] Where R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; R ei is the equivalent resistance of the induction motor load; Xei is the equivalent reactance of the induction motor load; s i,x is the slip value of the load node at the moment of emergency control action; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K L is the load factor; u i,cri and s i,cri are the critical voltage and critical slip values ​​of the load node.

[0022] Furthermore, the emergency control measure quantity Q i,x , which is calculated as follows:

[0023]

[0024] Where Q inow is the current total reactive power of the induction motor load node; X i is the equivalent line reactance.

[0025] Furthermore, when the load node bus voltage u is detected m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends, including:

[0026] Combined with the actual operation of the power grid, with the constraint of not exceeding the high-voltage protection set value, the value in the interval [1.0,1.03]pu is selected as the emergency control exit threshold u out ;

[0027] Detect the induction motor load bus node voltage u m , taking the scanning calculation step length as one detection cycle, calculate the reactive voltage sensitivity k of the induction motor load node i , as follows:

[0028]

[0029] Where, u1 is the node bus voltage of the previous detection cycle; u2 is the node bus voltage of the current detection cycle; Q1 is the node bus reactive power of the previous detection cycle; Q2 is the node bus reactive power of the current detection cycle;

[0030] When the induction motor load bus node voltage u is detected m Greater than or equal to the emergency control exit threshold u out , then the reactive power is withdrawn; with the node voltage not lower than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j, where j = 1, 2, 3, ...:

[0031]

[0032] Determine the reactive power surplus Q rest Whether the exit quantity ΔQ is met j If Q rest ≥ΔQ j , then press ΔQ j Exit reactive power, j increases by 1, and re-detect the induction motor load bus node voltage u m If Q rest <ΔQ j , then proceed to the next step, where the reactive power surplus Q rest The calculation formula is as follows:

[0033]

[0034] Press Q rest The remaining reactive power is withdrawn, and all reactive power invested during the emergency control period is withdrawn, and the emergency control ends.

[0035] Based on the same inventive concept, the present invention provides an emergency reactive power control system suitable for node voltage instability, comprising:

[0036] The fault trigger set determination module is used to scan the N-2 AC expected faults in the power grid and determine all faults that cause node voltage instability as fault trigger set A. i , where i = 1, 2, 3, ...;

[0037] Emergency control measure quantity determination module is used to obtain the fault trigger set A through offline simulation i The instantaneous voltage value u of the fault node under different voltage drop degrees of each fault i,fault,x and the voltage value u at the time of emergency control action of the load node i,x , slip value s i,x ; Used to calculate the fault trigger set A in combination with load operating parameters i Critical voltage value u of medium load node i,cri and critical slip value s i,cri ; According to the voltage value u i,x , slip value s i,x and critical voltage u i,cri , critical slip value s i,cri Size, calculate the minimum target voltage value u of the load node target,i,x , and then calculate the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x ;

[0038] The strategy start module during emergency control is used to trigger set A when a power grid failure is detected. i When a fault occurs, the emergency control is started to obtain the instantaneous voltage value u of the fault node. i,fault , matching the instantaneous voltage value u of the fault node i,fault The voltage range [u i,fault,n ,u i,fault,n+1 ], the minimum value u of the fault node voltage interval is applied to the load node i,fault,n The amount of emergency control measures Q i,n ;

[0039] Emergency control exit strategy startup module is used to detect the load node bus voltage u m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually exit the reactive power invested during the emergency control period until all are exited and the emergency control strategy ends.

[0040] Furthermore, the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x , the calculation process is as follows:

[0041] Set the voltage drop step size and scan the fault trigger set A separately i For the different severity of the same fault, record the instantaneous voltage value of the fault node, and count them in order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and record the voltage value u of the load node at the time of emergency control action. i,x , slip value s i,x

[0042] According to the electromagnetic power characteristic equation of the induction motor load P ei (u,s) and mechanical power P mi (s), calculate the tangent point of the two characteristic curves (u i,cri ,s i,cri ), and the critical voltage value u of the load node is obtained i,cri and critical slip value s i,cri ;

[0043] Compare the slip value s at the moment of emergency control action of the load node i,x Slip value s with load node i,cri The size of s i,x i,cri , then u target,i,x =u i,cri ; If s i,x ≥s i,cri ​, then calculate the electromagnetic power characteristic equation of the induction motor P ei (u,s) and mechanical power characteristic equation P mi (s) When the slip value is equal to s i,x The intersection point when the voltage at the intersection point is taken as the minimum target voltage value u target,i,x ;

[0044] According to the voltage value u at the time of emergency control action of the load node i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures Q i,x .

[0045] Furthermore, the tangent point (u i,cri ,s i,cri ), which is calculated as follows:

[0046]

[0047] Among them, R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K Li is the load factor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load; the equivalent resistance of the induction motor load R ei and reactance X ei The calculation formula is as follows:

[0048]

[0049] Among them, X mi is the magnetizing reactance of the induction motor load; R si is the stator resistance of the induction motor load; X si is the stator reactance of the induction motor load; j is a complex unit.

[0050] Furthermore, the minimum target voltage value u target,i,x , which is calculated as follows:

[0051]

[0052] Where R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; R ei is the equivalent resistance of the induction motor load; X eiis the equivalent reactance of the induction motor load; s i,x is the slip value of the load node at the moment of emergency control action; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K L is the load factor; u i,cri and s i,cri are the critical voltage and critical slip values ​​of the load node.

[0053] Furthermore, the emergency control measure quantity Q i,x , which is calculated as follows:

[0054]

[0055] Where Q inow is the current total reactive power of the induction motor load node; X i is the equivalent line reactance.

[0056] Furthermore, when the load node bus voltage u is detected m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends, including:

[0057] Combined with the actual operation of the power grid, with the constraint of not exceeding the high-voltage protection set value, the value in the interval [1.0,1.03]pu is selected as the emergency control exit threshold u out ;

[0058] Detect the induction motor load bus node voltage u m , taking the scanning calculation step length as one detection cycle, calculate the reactive voltage sensitivity k of the induction motor load node i , as follows:

[0059]

[0060] Where, u1 is the node bus voltage of the previous detection cycle; u2 is the node bus voltage of the current detection cycle; Q1 is the node bus reactive power of the previous detection cycle; Q2 is the node bus reactive power of the current detection cycle;

[0061] When the induction motor load bus node voltage u is detected m Greater than or equal to the emergency control exit threshold u out , then the reactive power is withdrawn; with the node voltage not lower than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j , where j = 1, 2, 3, ...:

[0062]

[0063] Determine the reactive power surplus Q rest Whether the exit quantity ΔQ is met j If Q rest ≥ΔQ j , then press ΔQ j Exit reactive power, j increases by 1, and re-detect the induction motor load bus node voltage u m If Q rest <ΔQ j , then proceed to the next step, where the reactive power surplus Q rest The calculation formula is as follows:

[0064]

[0065] Press Q rest The remaining reactive power is withdrawn, and all reactive power invested during the emergency control period is withdrawn, and the emergency control ends.

[0066] Based on the same inventive concept, the present invention provides an emergency reactive power control device suitable for node voltage instability, including a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the above-mentioned emergency reactive power control method suitable for node voltage instability.

[0067] Based on the same inventive concept, a computer-readable storage medium of the present invention stores a computer program thereon, which, when executed by a processor, implements the steps of the above-mentioned emergency reactive power control method applicable to node voltage instability.

[0068] Beneficial effects: Compared with the prior art, the present invention has the following significant technical effects:

[0069] The present invention achieves precise emergency control of reactive power measures by distinguishing different degrees of fault voltage drop and the size of the slip value at the time of emergency control action, efficiently utilizes dynamic reactive resources near the node, suppresses voltage instability at the load node, prevents grid voltage collapse, and improves power system voltage stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 This is a flow chart of an emergency reactive power control method applicable to node voltage instability disclosed in an embodiment of the present invention;

[0071] Figure 2 This is a schematic structural diagram of an emergency reactive power control system applicable to node voltage instability disclosed in an embodiment of the present invention;

[0072] Figure 3 The present invention discloses an emergency reactive power control device suitable for node voltage instability. DETAILED DESCRIPTION

[0073] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It will be understood by those skilled in the art that the purposes and advantages that can be achieved by the present invention are not limited to the specific description of the above beneficial effects, and the above and other purposes that can be achieved by the present invention will be more clearly understood based on the following detailed description.

[0074] It should be understood by those skilled in the art that the exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Whether hardware or software is used depends on the specific application and design and tree conditions of the technical solution. Professionals and technicians may use different methods to implement the functions described for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0075] References to "embodiments" in this disclosure mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0076] Example 1

[0077] See also Figure 1 , Figure 1 This is a flow chart of an emergency reactive power control method applicable to node voltage instability disclosed in an embodiment of the present invention. Figure 1 The described emergency reactive power control method is applied to power systems, such as for suppressing voltage instability at load nodes such as induction motors, etc., which is not limited in the embodiments of the present invention. Figure 1 As shown, the emergency reactive power control method applicable to node voltage instability may include the following operations:

[0078] S1. Fault trigger set determination: Scan the grid N-2 AC expected faults and determine all faults that cause node voltage instability as fault trigger set A. i , where i = 1, 2, 3, ...

[0079] S2. Determination of emergency control measures: Obtain fault trigger set A through offline simulation i The instantaneous voltage value u of the fault node under different voltage drop degrees of each fault i,fault,xand the voltage value u at the time of emergency control action of the load node i,x , slip value s i,x ; Combined with the load operating parameters, calculate the fault trigger set A i Critical voltage value u of medium load node i,cri and critical slip value s i,cri ; According to the voltage value u i,x , slip value s i,x and critical voltage u i,cri , critical slip value s i,cri Size, calculate the minimum target voltage value u of the load node target,i,x , and then calculate the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x The specific steps include:

[0080] S2.1, with 0.1pu as a voltage drop step, scan the fault trigger set A respectively i For the different severity of the same fault, record the instantaneous voltage value of the fault node, and count them in order from small to large as u i,fault,x , where x = 1, 2, 3, ..., 10. At the same time, record the voltage value u of the load node at the time of emergency control action i,x , slip value s i,x .

[0081] S2.2, critical voltage value u i,cri and critical slip value s i,cri Setting: According to the electromagnetic power characteristic equation P of the induction motor load ei (u,s) and mechanical power P mi (s), calculate the tangent point of the two characteristic curves (u i,cri ,s i,cri ), and the critical voltage value u of the load node is obtained i,cri and critical slip value s i,cri , as shown in formula (1) (2):

[0082]

[0083] Among them, R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K Li is the load factor; R ei is the equivalent resistance of the induction motor load; X eiis the equivalent reactance of the induction motor load. ei and reactance X ei The calculation formula is shown in formula (3):

[0084]

[0085] Among them, X mi is the magnetizing reactance of the induction motor load; R si is the stator resistance of the induction motor load; X si is the stator reactance of the induction motor load; j is a complex unit.

[0086] S2.3, minimum target voltage value u target,i,x Setting: Compare the slip value s at the moment of emergency control action of the load node i,x Critical slip value s of the load node i,cri The size of s i,x i,cri , then u target,i,x =u i,cri ; If s i,x ≥s i,cri , then calculate the electromagnetic power characteristic equation of the induction motor P ei (u,s) and mechanical power characteristic equation P mi (s) When the slip value is equal to s i,x The intersection point when the voltage at the intersection point is taken as the minimum target voltage value u target,i,x , as shown in formula (4):

[0087]

[0088] Where R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load; s i,x is the slip value of the load node at the moment of emergency control action; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K L is the load factor; u i,cri and s i,cri are the critical voltage and critical slip values ​​of the load node.

[0089] S2.4. Emergency control measures quantity Q i,x Setting: According to the voltage value u at the time of emergency control action of the load node i,x And the minimum target voltage value u​target,i,x , calculate the required emergency control measures Q i,x , as shown in formula (5):

[0090]

[0091] Where Q inow is the current total reactive power of the induction motor load node; X i is the equivalent line reactance.

[0092] S3, emergency control period strategy: when a power grid failure is detected, set A is triggered i When a fault occurs, the emergency control is started to obtain the instantaneous voltage value u of the fault node. i,fault , matching the instantaneous voltage value u of the fault node i,fault The voltage range [u i,fault,n ,u i,fault,n+1 ], the minimum value u of the fault node voltage interval is applied to the load node i,fault,n The corresponding emergency control measure quantity Q i,n .

[0093] In this embodiment, when a system failure is detected, set A is triggered. i When there is a fault inside, start emergency control; otherwise, end.

[0094] S4, emergency control exit strategy: When the load node bus voltage u m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends. Specifically, it includes the following steps:

[0095] S4.1. Based on the actual operation of the power grid, and subject to the constraint of not exceeding the high-voltage protection set value, appropriately select a value in the interval [1.0, 1.03] pu as the emergency control exit threshold u out .

[0096] S4.2. Detect the induction motor load bus node voltage u m , taking the scanning calculation step length as one detection cycle, calculate the reactive voltage sensitivity k of the induction motor load node i , as shown in formula (6):

[0097]

[0098] Where, u1 is the node bus voltage of the previous detection cycle; u2 is the node bus voltage of the current detection cycle; Q1 is the node bus reactive power of the previous detection cycle; Q2 is the node bus reactive power of the current detection cycle;

[0099] S4.3, when the induction motor load bus node voltage u is detected m Greater than or equal to the emergency control exit threshold u out , then the reactive power is withdrawn; with the node voltage not lower than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j , where j = 1, 2, 3, ..., as shown in formula (7). Otherwise, return to step S4.2.

[0100]

[0101] S4.4. Determine the reactive power remaining Q rest Whether the exit quantity ΔQ is met j If Q rest ≥ΔQ j , then press ΔQ j Exit reactive power, j increases by 1, and return to step S4.2 to re-detect the induction motor load bus node voltage u m If Q rest <ΔQ j , then go to step S4.5; wherein, the reactive surplus Q rest The calculation formula is as follows:

[0102]

[0103] S4.5. Press Q rest The remaining reactive power is withdrawn, and all reactive power invested during the emergency control period is withdrawn, and the emergency control ends.

[0104] This invention addresses load node voltage instability scenarios. Based on varying fault voltage drop levels, it compares the slip value at the moment of emergency control action with the critical slip value to assess reactive power measures during emergency control. Emergency control is triggered by a grid fault and, by comparing the load node bus voltage with the emergency reactive power exit threshold, fully considers the reactive voltage sensitivity of the load node and implements the emergency control exit strategy sequentially.

[0105] The present invention comprehensively considers the different fault severity levels and different operating states of induction motors, calculates different emergency control measures, and efficiently utilizes dynamic reactive resources near the nodes. It can effectively suppress voltage instability at load nodes and improve the voltage stability of the power system.

[0106] Example 2

[0107] See also Figure 2 , Figure 2 This is a schematic diagram of the structure of an emergency reactive power control system applicable to node voltage instability disclosed in an embodiment of the present invention. The system can suppress voltage instability at load nodes such as induction motors, and specifically includes:

[0108] The fault trigger set determination module is used to scan the N-2 AC expected faults in the power grid and determine all faults that cause node voltage instability as fault trigger set A. i , where i = 1, 2, 3, ...;

[0109] Emergency control measure quantity determination module is used to obtain the fault trigger set A through offline simulation i The instantaneous voltage value u of the fault node under different voltage drop degrees of each fault i,fault,x and the voltage value u at the time of emergency control action of the load node i,x , slip value s i,x ; Used to calculate the fault trigger set A in combination with load operating parameters i The critical voltage value u that causes load voltage instability i,cri and critical slip value s i,cri ; According to the voltage value u i,x , slip value s i,x and critical voltage u i,cri , critical slip value s i,cri Size, calculate the minimum target voltage value u of the load node target,i,x , and then calculate the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x ;

[0110] The strategy start module during emergency control is used to trigger set A when a power grid failure is detected. i When a fault occurs, the emergency control is started to obtain the instantaneous voltage value u of the fault node. i,fault , matching the instantaneous voltage value u of the fault node i,fault The voltage range [u i,fault,n ,u i,fault,n+1 ], the minimum value u of the fault node voltage interval is applied to the load node i,fault,n The amount of emergency control measures Q i,n ;

[0111] Emergency control exit strategy startup module is used to detect the load node bus voltage u m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually exit the reactive power invested during the emergency control period until all are exited and the emergency control strategy ends.

[0112] In an optional embodiment, the emergency reactive power control method applicable to node voltage instability includes: a) scanning the N-2 AC expected faults in the power grid, and determining all faults that cause node voltage instability as a fault trigger set; b) based on the offline simulation of the N-2 AC fault in the power grid, obtaining the voltage value and slip value of the load node under different voltage drop degrees of the fault at the moment of emergency control action, comparing them with the critical voltage value and critical slip value of the load node, and calculating the amount of emergency control measures; c) triggering emergency control through the power grid fault, timely matching the interval of the fault voltage drop value, and obtaining the amount of emergency control measures; d) when the load node voltage is greater than or equal to the emergency control exit threshold, gradually exiting the reactive power invested during the emergency control period.

[0113] In one embodiment, the emergency control measure quantity determination module is used for the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x , the calculation process is as follows:

[0114] Set the voltage drop step size and scan the fault trigger set A separately i For the different severity of the same fault, record the instantaneous voltage value of the fault node, and count them in order from small to large as u i,fault,x , where x = 1, 2, 3, ...;

[0115] According to the electromagnetic power characteristic equation of the induction motor load P ei (u,s) and mechanical power P mi (s), calculate the tangent point of the two characteristic curves (u i,cri ,s i,cri ), and the critical voltage value u of the load node is obtained i,cri and critical slip value s i,cri ;

[0116] Compare the slip value s at the moment of emergency control action of the load node i,x Critical slip value s of the load node i,cri The size of s i,x i,cri , then u target,i,x =u i,cri ; If s i,x ≥s i,cri , then calculate the electromagnetic power characteristic equation of the induction motor P ei (u,s) and mechanical power characteristic equation P mi The slip value of (s) is equal to s i,x The intersection point when the voltage at the intersection point is taken as the minimum target voltage value u target,i,x ;

[0117] According to the voltage value u at the time of emergency control action of the load node​i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures Q i,x .

[0118] In one embodiment, the emergency control measure determination module is used to calculate the tangent point (u i,cri ,s i,cri ), which is calculated as follows:

[0119]

[0120] Among them, R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K Li is the load factor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load. ei and reactance X ei The calculation formula is as follows:

[0121]

[0122] Among them, X mi is the magnetizing reactance of the induction motor load; R si is the stator resistance of the induction motor load; X si is the stator reactance of the induction motor load; j is a complex unit.

[0123] In one embodiment, the emergency control measure determination module is used to calculate the minimum target voltage value u target,i,x , which is calculated as follows:

[0124]

[0125] Where R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load; s i,x is the slip value of the load node at the moment of emergency control action; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K L is the load factor; ui,cri and s i,cri are the critical voltage and critical slip values ​​of the load node.

[0126] In one embodiment, the emergency control measure quantity determination module is used to calculate the emergency control measure quantity Q i,x , which is calculated as follows:

[0127]

[0128] Where Q inow is the current total reactive power of the induction motor load node; X i is the equivalent line reactance.

[0129] In one embodiment, the emergency control strategy startup module is used to detect the load node bus voltage u m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends, including:

[0130] Combined with the actual operation of the power grid, with the constraint of not exceeding the high-voltage protection set value, the value in the interval [1.0,1.03]pu is appropriately selected as the emergency control exit threshold u out ;

[0131] Detect the induction motor load bus node voltage u m , taking the scanning calculation step length as one detection cycle, calculate the reactive voltage sensitivity k of the induction motor load node i , as follows:

[0132]

[0133] Where, u1 is the node bus voltage of the previous detection cycle; u2 is the node bus voltage of the current detection cycle; Q1 is the node bus reactive power of the previous detection cycle; Q2 is the node bus reactive power of the current detection cycle;

[0134] When the induction motor load bus node voltage u is detected m Greater than or equal to the emergency control exit threshold u out , then the reactive power is withdrawn; with the node voltage not lower than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j , where j = 1, 2, 3, ...:

[0135]

[0136] Determine the reactive power surplus Q rest Whether the exit quantity ΔQ is metj If Q rest ≥ΔQ j , then press ΔQ j Exit reactive power, j increases by 1, and re-detect the induction motor load bus node voltage u m If Q rest <ΔQ j , then proceed to the next step, where the reactive power surplus Q rest The calculation formula is as follows:

[0137]

[0138] Press Q rest The remaining reactive power is withdrawn, and all reactive power invested during the emergency control period is withdrawn, and the emergency control ends.

[0139] Example 3

[0140] See also Figure 3 , Figure 3 This is a schematic diagram of the structure of an emergency reactive power control device suitable for node voltage instability disclosed in an embodiment of the present invention. Figure 3 The described device can be applied to power systems, such as for suppressing voltage instability at load nodes such as induction motors, etc., and the embodiments of the present invention do not limit this.

[0141] like Figure 3 As shown, the device may include a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the method described in the above embodiment and can achieve technical effects consistent with the above method.

[0142] The memory may include computer system readable media in the form of volatile memory, such as random access memory (RAM) and / or cache memory. The device may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, the memory may be used to read and write non-removable, non-volatile magnetic media (commonly referred to as a "hard drive"). A program / utility having a set (at least one) of program modules may be stored in, for example, the memory, such program modules including but not limited to an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment. The program modules typically perform the functions and / or methods of the embodiments described herein.

[0143] The processor executes various functional applications and data processing by running the programs stored in the memory, such as implementing the method provided in the first embodiment of the present invention.

[0144] Example 4

[0145] Embodiment 4 of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the method described in the above embodiment are implemented and the technical effect consistent with the above method can be achieved.

[0146] The computer storage medium of the embodiment of the present invention can adopt any combination of one or more computer-readable media. Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or components, or any combination thereof. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by an instruction execution system, device or device or used in combination with it.

[0147] A computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0148] Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0149] The computer program code for performing the operations of the present invention can be written in one or more programming languages, or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0150] Of course, the computer-executable instructions of a storage medium provided by an embodiment of the present invention are not limited to the above method operations, but can also execute related operations in the method provided by any embodiment of the present invention.

[0151] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An emergency reactive power control method suitable for node voltage instability, characterized in that: include: Scan the grid N-2 AC anticipated faults and identify all faults that cause node voltage instability as fault trigger set A i , where i = 1, 2, 3, ...; Obtain fault trigger set A through offline simulation i The instantaneous voltage value u of the fault node under different voltage drop degrees of each fault i,fault,x and the voltage value u at the time of emergency control action of the load node i,x , slip value s i,x ; Combined with the load operating parameters, calculate the fault trigger set A i Critical voltage value u of medium load node i,cri and critical slip value s i,cri ; According to the voltage value u i,x , slip value s i,x and critical voltage u i,cri , critical slip value s i,cri Size, calculate the minimum target voltage value u of the load node target,i,x , and then calculate the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x ; When a power grid fault is detected, the triggering set A i When a fault occurs, the emergency control is started to obtain the instantaneous voltage value u of the fault node. i,fault , matching the instantaneous voltage value u of the fault node i,fault The voltage range [u i,fault,n ,u i,fault,n+1 ], the minimum value u of the fault node voltage interval is applied to the load node i,fault,n The corresponding emergency control measure quantity Q i,n ; When the load node bus voltage u is detected m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually exit the reactive power invested during the emergency control period until all are exited and the emergency control strategy ends.

2. The emergency reactive power control method applicable to node voltage instability according to claim 1, characterized in that: The fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x , the calculation process is as follows: Set the voltage drop step size and scan the fault trigger set A separately i For the different severity of the same fault, record the instantaneous voltage value of the fault node, and count them in order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and record the voltage value u of the load node at the time of emergency control action. i,x , slip value s i,x ; According to the electromagnetic power characteristic equation of the induction motor load P ei (u,s) and mechanical power P mi (s), calculate the tangent point of the two characteristic curves (u i,cri ,s i,cri ), and the critical voltage value u of the load node is obtained i,cri and critical slip value s i,cri ; Compare the slip value s at the time of emergency control action of the load node i,x Critical slip value s of the load node i,cri The size of s i,x i,cri , then u target,i,x =u i,cri ; If s i,x ≥s i,cri , then calculate the electromagnetic power characteristic equation of the induction motor P ei (u,s) and mechanical power characteristic equation P mi (s) When the slip value is equal to s i,x The intersection point when the voltage at the intersection point is taken as the minimum target voltage value u target,i,x ;​ According to the voltage value u at the time of emergency control action of the load node i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures Q i,x .

3. The emergency reactive power control method applicable to node voltage instability according to claim 2, characterized in that: The tangent point (u i,cri ,s i,cri ), which is calculated as follows: Among them, R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K Li is the load factor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load, and the equivalent resistance of the induction motor load R ei and reactance X ei The calculation formula is as follows: Among them, X mi is the magnetizing reactance of the induction motor load; R si is the stator resistance of the induction motor load; X si is the stator reactance of the induction motor load; j is a complex unit.

4. The emergency reactive power control method applicable to node voltage instability according to claim 2, characterized in that: The minimum target voltage value u target,i,x , which is calculated as follows: Where R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load; s i,x is the slip value at the moment of emergency control action of the load node; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K L is the load factor; u i,cri and s i,cri are the critical voltage and critical slip values ​​of the load node.

5. The emergency reactive power control method applicable to node voltage instability according to claim 2, characterized in that: The emergency control measure quantity Q i,x , which is calculated as follows: Where Q inow is the current total reactive power of the induction motor load node; X i is the equivalent line reactance.

6. The emergency reactive power control method applicable to node voltage instability according to claim 1, characterized in that: When the load node bus voltage u is detected m Greater than or equal to the emergency control exit threshold u out , emergency control exit; Reference load node reactive voltage sensitivity k i , gradually withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends, including: Combined with the actual operation of the power grid, with the constraint of not exceeding the high-voltage protection set value, the value in the interval [1.0,1.03]pu is selected as the emergency control exit threshold u out ; Detect the induction motor load bus node voltage u m , taking the scanning calculation step length as one detection cycle, calculate the reactive voltage sensitivity k of the induction motor load node i , as follows: Where, u1 is the node bus voltage of the previous detection cycle; u2 is the node bus voltage of the current detection cycle; Q1 is the node bus reactive power of the previous detection cycle; Q2 is the node bus reactive power of the current detection cycle; When the induction motor load bus node voltage u is detected m Greater than or equal to the emergency control exit threshold u out , then the reactive power is withdrawn; with the node voltage not lower than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j , where j = 1, 2, 3, ...: Determine the reactive power surplus Q rest Whether the exit quantity ΔQ is met j If Q rest ≥ΔQ j , then press ΔQ j Exit reactive power, j increases by 1, and re-detect the induction motor load bus node voltage u m If Q rest <ΔQ j , then proceed to the next step, where the reactive power surplus Q rest The calculation formula is as follows: Press Q rest The remaining reactive power is withdrawn, and all reactive power invested during the emergency control period is withdrawn, and the emergency control ends.

7. An emergency reactive power control system suitable for node voltage instability, characterized in that: include: The fault trigger set determination module is used to scan the N-2 AC expected faults in the power grid and determine all faults that cause node voltage instability as fault trigger set A. i , where i = 1, 2, 3, ...; Emergency control measure quantity determination module is used to obtain the fault trigger set A through offline simulation i The instantaneous voltage value u of the fault node under different voltage drop degrees of each fault i,fault,x and the voltage value u at the time of emergency control action of the load node i,x , slip value s i,x ; Used to calculate the fault trigger set A in combination with load operating parameters i Critical voltage value u of medium load node i,cri and critical slip value s i,cri ; According to the voltage value u i,x , slip value s i,x and critical voltage u i,cri , critical slip value s i,cri Size, calculate the minimum target voltage value u of the load node target,i,x , and then calculate the fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x ; The strategy start module during emergency control is used to trigger set A when a power grid failure is detected. i When a fault occurs, the emergency control is started to obtain the instantaneous voltage value u of the fault node. i,fault , matching the instantaneous voltage value u of the fault node i,fault The voltage range [u i,fault,n ,u i,fault,n+1 ], the minimum value u of the fault node voltage interval is applied to the load node i,fault,n The amount of emergency control measures Q i,n ; Emergency control exit strategy startup module is used to detect the load node bus voltage u m Greater than or equal to the emergency control exit threshold u out , emergency control exit; refer to load node reactive voltage sensitivity k i , gradually exit the reactive power invested during the emergency control period until all are exited and the emergency control strategy ends.

8. The emergency reactive power control system applicable to node voltage instability according to claim 7, characterized in that: The fault trigger set A i The emergency control measures Q under different voltage drop degrees of each fault i,x , the calculation process is as follows: Set the voltage drop step size and scan the fault trigger set A separately i For the different severity of the same fault, record the instantaneous voltage value of the fault node, and count them in order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and record the voltage value u of the load node at the time of emergency control action. i,x , slip value s i,x ; According to the electromagnetic power characteristic equation of the induction motor load P ei (u,s) and mechanical power P mi (s), calculate the tangent point of the two characteristic curves (u i,cri ,s i,cri ), and the critical voltage value u of the load node is obtained i,cri and critical slip value s i,cri ; Compare the slip value s at the moment of emergency control action of the load node i,x Critical slip value s of the load node i,cri The size of s i,x i,cri , then u target,i,x =u i,cri ; If s i,x ≥s i,cri , then calculate the electromagnetic power characteristic equation of the induction motor P ei (u,s) and mechanical power characteristic equation P mi (s) When the slip value is equal to s i,x The intersection point when the voltage at the intersection point is taken as the minimum target voltage value u target,i,x ;​ According to the voltage value u at the time of emergency control action of the load node i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures Q i,x .

9. The emergency reactive power control system applicable to node voltage instability according to claim 8, characterized in that: The tangent point (u i,cri ,s i,cri ), which is calculated as follows: Among them, R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K Li is the load factor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load; the equivalent resistance of the induction motor load R ei and reactance X ei The calculation formula is as follows: Among them, X mi is the magnetizing reactance of the induction motor load; R si is the stator resistance of the induction motor load; X si is the stator reactance of the induction motor load; j is a complex unit.

10. The emergency reactive power control system applicable to node voltage instability according to claim 8, characterized in that: The minimum target voltage value u target,i,x , which is calculated as follows: Where R ri is the load rotor resistance of the induction motor; X ri is the load rotor reactance of the induction motor; R ei is the equivalent resistance of the induction motor load; X ei is the equivalent reactance of the induction motor load; s i,x is the slip value of the load node at the moment of emergency control action; ω si is the synchronous speed of the induction motor; α i is the mechanical load torque coefficient; m is the mechanical load torque power; K L is the load factor; u i,cri and s i,cri are the critical voltage and critical slip values ​​of the load node.

11. The emergency reactive power control system applicable to node voltage instability according to claim 8, characterized in that: The emergency control measure quantity Q i,x , which is calculated as follows: Where Q inow is the current total reactive power of the induction motor load node; X i is the equivalent line reactance.

12. The emergency reactive power control system applicable to node voltage instability according to claim 7, characterized in that: When the load node bus voltage u is detected m Greater than or equal to the emergency control exit threshold u out , emergency control exit; Reference load node reactive voltage sensitivity k i , gradually withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends, including: Combined with the actual operation of the power grid, with the constraint of not exceeding the high-voltage protection set value, the value in the interval [1.0,1.03]pu is selected as the emergency control exit threshold u out ; Detect the induction motor load bus node voltage u m , taking the scanning calculation step length as one detection cycle, calculate the reactive voltage sensitivity k of the induction motor load node i , as follows: Where, u1 is the node bus voltage of the previous detection cycle; u2 is the node bus voltage of the current detection cycle; Q1 is the node bus reactive power of the previous detection cycle; Q2 is the node bus reactive power of the current detection cycle; When the induction motor load bus node voltage u is detected m Greater than or equal to the emergency control exit threshold u out , then the reactive power is withdrawn; with the node voltage not lower than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j , where j = 1, 2, 3, ...: Determine the reactive power surplus Q rest Whether the exit quantity ΔQ is met j If Q rest ≥ΔQ j , then press ΔQ j Exit reactive power, j increases by 1, and re-detect the induction motor load bus node voltage u m If Q rest <ΔQ j , then proceed to the next step, where the reactive power surplus Q rest The calculation formula is as follows: Press Q rest The remaining reactive power is withdrawn, and all reactive power invested during the emergency control period is withdrawn, and the emergency control ends.

13. An emergency reactive power control device suitable for node voltage instability, characterized in that: The electronic device comprises a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the emergency reactive power control method applicable to node voltage instability as described in any one of claims 1 to 6.

14. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the emergency reactive power control method applicable to node voltage instability as claimed in any one of claims 1 to 6.

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