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

Abstract

The invention discloses an emergency reactive power control method, system and device suitable for node voltage instability and a storage medium, and the method comprises the steps: obtaining the voltage value and slip frequency of a load node at an emergency control action moment under different voltage drop degrees of a fault based on the off-line simulation of an N-2 AC fault of a power grid; comparing with a critical voltage value and a critical slip value of a load node, and calculating an emergency control measure quantity; emergency control is triggered through a power grid fault, an interval where a fault voltage drop value is located is matched in time, and an emergency control measure quantity is obtained; and when the load node voltage is greater than or equal to the emergency control exit threshold value, gradually exiting reactive power input during the emergency control period. According to the method, different severity degrees of faults and different operation states of the induction motor are comprehensively considered, different emergency control measure quantities are calculated, dynamic reactive power resources near nodes are efficiently utilized, load node voltage instability can be effectively restrained, and the voltage stability of a power system is improved.

Description

Technical Field

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

[0002] As the scale of power grid construction continues to expand, the load of the power system is increasing. The larger the proportion of dynamic and nonlinear loads, the less reactive support capacity, and the more likely the grid voltage is to become unstable. As one of the important loads in the urban power grid, the load characteristics of the induction motor are closely related to the voltage stability of the power system, and are particularly important for the safety of the power grid. The balance between the electromagnetic power and mechanical power of the induction motor affects the trend of the slip. When a system failure causes the bus voltage of the load node to drop, the electromagnetic power of the induction motor decreases rapidly, and the slip increases. If the critical stable 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: An emergency reactive power control method applicable to node voltage instability of the present invention comprises:

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

[0006] Through offline simulation, the fault trigger set A is obtained. 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 operation 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 levels of each faulti,x ;

[0007] When a power grid fault is detected, set A is triggered i When a fault occurs within the fault node, 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 withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends.

[0009] Furthermore, the fault trigger set A i The emergency control measures Q under different voltage drop levels 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 The different severity levels of the same fault in the fault node are recorded, and the instantaneous voltage value of the fault node is recorded in the order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and 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 ;

[0011] 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 ;

[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 at which the voltage is taken as the minimum target voltage value u target,i,x ;

[0013] According to the voltage value u of the load node at the time of emergency control action i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures quantity 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 , and its calculation formula is as follows:

[0020]

[0021] In the formula, 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 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 i,cri are the critical voltage value and critical slip value of the load node.

[0022] Furthermore, the emergency control measure quantity Q i,x , and its calculation formula is as follows:

[0023]

[0024] In the formula, 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 setting, the value in the interval [1.0,1.03]pu is selected as the emergency control exit threshold u out ;

[0027] Detect the bus node voltage u of the induction motor load 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] Wherein, 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 less 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-detects 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 is withdrawn, and the emergency control ends.

[0035] Based on the same inventive concept, an emergency reactive power control system applicable to node voltage instability of the present invention comprises:

[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] The 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 operation 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 levels of each fault i,x ;

[0038] The emergency control period strategy startup module is used to trigger set A when a power grid failure is detected. i When a fault occurs within the fault node, 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 withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends.

[0040] Furthermore, the fault trigger set A i The emergency control measures Q under different voltage drop levels 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 The different severity levels of the same fault in the fault node are recorded, and the instantaneous voltage value of the fault node is recorded in the order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and 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

[0042] 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 ;

[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 at which the voltage is taken as the minimum target voltage value u target,i,x ;

[0044] According to the voltage value u of the load node at the time of emergency control action i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures quantity 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 , and its calculation formula is as follows:

[0051]

[0052] In the formula, 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 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 i,cri are the critical voltage value and critical slip value of the load node.

[0053] Furthermore, the emergency control measure quantity Q i,x , and its calculation formula is as follows:

[0054]

[0055] In the formula, 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 setting, the value in the interval [1.0,1.03]pu is selected as the emergency control exit threshold u out ;

[0058] Detect the bus node voltage u of the induction motor load 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] Wherein, 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 less 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-detects 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 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 emergency reactive power control method suitable for node voltage instability as described above.

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

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

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

[0070] Figure 1 It 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 It is a structural schematic 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 invention discloses a schematic diagram of the structure of an emergency reactive power control device suitable for node voltage instability. DETAILED DESCRIPTION

[0073] The present invention is described in detail below in conjunction with 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 with 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 in the present invention can be implemented in hardware, software or a combination of the two. Whether it is implemented in hardware or software depends on the specific application and design of the technical solution. Professional and technical personnel can use different methods to implement the functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0075] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood 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 1 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 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, ….

[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 operation 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 levels 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 The different severity levels of the same fault in the fault node are recorded, and the instantaneous voltage value of the fault node is recorded in the order from small to large as u i,fault,x , where x = 1, 2, 3, ..., 10. At the same time, the voltage value u of the load node at the time of emergency control action is recorded 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 load node emergency control action time 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 at which the voltage is taken as the minimum target voltage value u target,i,x , as shown in formula (4):

[0087]

[0088] In the formula, 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 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 i,cri are the critical voltage value and critical slip value 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 quantity Q i,x , as shown in formula (5):

[0090]

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

[0092] S3, Strategy during emergency control: When a power grid failure is detected, set A is triggered i When a fault occurs within the fault node, 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 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. Specifically, it includes the following steps:

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

[0096] S4.2. Detect the bus node voltage u of the induction motor load 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] Wherein, 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 less 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 amount 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 enter step S4.5; wherein the reactive power 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 is withdrawn, and the emergency control ends.

[0104] The present invention aims at the scenario of voltage instability at the load node, and based on different fault voltage drop degrees, evaluates the reactive measures during the emergency control by comparing the slip value at the time of emergency control action with the critical slip value. The emergency control is triggered by a power grid fault, and by comparing the bus voltage value of the load node with the emergency reactive exit threshold, the reactive voltage sensitivity of the load node is fully considered, and the emergency control exit strategy is completed one by one.

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

[0106] Example 2

[0107] See also Figure 2 , Figure 2 The present invention discloses an emergency reactive power control system applicable to node voltage instability. The system can suppress node voltage instability of loads 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] The 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 operation 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 levels of each fault i,x ;

[0110] The emergency control period strategy startup module is used to trigger set A when a power grid failure is detected. i When a fault occurs within the fault node, 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 withdraw the reactive power invested during the emergency control period until all are withdrawn, 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 anticipated AC faults of the N-2 power grid, and determining all faults that cause node voltage instability as a fault trigger set; b) based on the offline simulation of the AC fault of the N-2 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, and 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 power grid faults, 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 levels 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 The different severity levels of the same fault in the fault node are recorded, and the instantaneous voltage value of the fault node is recorded in the order from small to large as u i,fault,x , where x = 1, 2, 3, ...;

[0115] 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 ;

[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 (s) The slip value is equal to s i,x The intersection point at which the voltage is taken as the minimum target voltage value u target,i,x ;

[0117] According to the voltage value u of the load node at the time of emergency control action​i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures quantity 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 , and its calculation formula is as follows:

[0124]

[0125] In the formula, 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 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 i,cri are the critical voltage value and critical slip value 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 , and its calculation formula is as follows:

[0127]

[0128] In the formula, 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 period 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 setting, the value in the interval [1.0,1.03]pu is appropriately selected as the emergency control exit threshold u out ;

[0131] Detect the bus node voltage u of the induction motor load 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] Wherein, 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 less 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-detects 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 is withdrawn, and the emergency control ends.

[0139] Example 3

[0140] See also Figure 3 , Figure 3 1 is a schematic diagram of the structure of an emergency reactive power control device applicable to 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 are not limited thereto.

[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 the technical effect 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 the implementation of a network environment. The program modules typically perform the functions and / or methods in the embodiments described herein.

[0143] The processor executes various functional applications and data processing by running the program 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. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. 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 of the above. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, a device or a device or used in combination with it.

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

[0148] The program code embodied on the 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] Computer program code for performing the operation of the present invention may be written in one or more programming languages ​​or combinations 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 may 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 may 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 may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0150] Of course, the storage medium containing computer executable instructions provided by an embodiment of the present invention, whose computer executable instructions are not limited to the above method operations, 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 description is only a specific embodiment of the present invention and is 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 N-2 AC expected faults in the power grid and identify all faults that cause node voltage instability as fault trigger set A i , where i = 1, 2, 3, ...; Through offline simulation, the fault trigger set A is obtained. 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 operation 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 levels of each fault i,x ; When a power grid fault is detected, set A is triggered i When a fault occurs within the fault node, 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 withdraw the reactive power invested during the emergency control period until all are withdrawn, and the emergency control strategy ends.

2. The method for emergency reactive power control 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 levels 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 The different severity levels of the same fault in the fault node are recorded, and the instantaneous voltage value of the fault node is recorded in the order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and 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 ; 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 ; 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 at which the voltage is taken as the minimum target voltage value u target,i,x ;​ According to the voltage value u of the load node at the time of emergency control action i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures quantity 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 method for emergency reactive power control applicable to node voltage instability according to claim 2, characterized in that: The minimum target voltage value u target,i,x , and its calculation formula is as follows: In the formula, 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 i,cri are the critical voltage value and critical slip value 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 , and its calculation formula is as follows: In the formula, Q inow is the current total reactive power of the induction motor load node; X i is the equivalent line reactance.

6. The method for emergency reactive power control 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 setting, 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: Wherein, 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 less than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j , where j = 1, 2, 3, ...: 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 re-detects 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, ...; The 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 operation 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 levels of each fault i,x ; The emergency control period strategy startup module is used to trigger set A when a power grid failure is detected. i When a fault occurs within the fault node, 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 withdraw the reactive power invested during the emergency control period until all are withdrawn, 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 levels 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 The different severity levels of the same fault in the fault node are recorded, and the instantaneous voltage value of the fault node is recorded in the order from small to large as u i,fault,x , where x = 1, 2, 3, ...; and 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 ; 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 ; 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 at which the voltage is taken as the minimum target voltage value u target,i,x ;​ According to the voltage value u of the load node at the time of emergency control action i,x And the minimum target voltage value u target,i,x , calculate the required emergency control measures quantity 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 , and its calculation formula is as follows: In the formula, 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 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 i,cri are the critical voltage value and critical slip value 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 , and its calculation formula is as follows: In the formula, 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 setting, 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: Wherein, 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 less than 0.85pu as the constraint, calculate the reactive power withdrawal amount ΔQ j , where j = 1, 2, 3, ...: 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 re-detects 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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