Power angle stability interval division and control method and system based on wide-area branch response

Abstract

The present application belongs to the field of power system safety and stability analysis, and discloses a power angle stability interval division and control method and system based on wide-area branch response; the method comprises the following steps: identifying a key branch k in a power system; judging whether the unit power angle in the power system is unstable according to the key branch k; if it is judged that the unit power angle in the power system is unstable, entering the judgment step of the instability zone; otherwise, entering the judgment step of the emergency zone and the warning zone; the judgment step of the instability zone: if it is judged that the power system has entered the instability zone, disconnecting the key branch k from the power system; the judgment step of the emergency zone and the warning zone: if it is judged that the power system has entered the emergency zone or the warning zone, cutting off part of the generator power from the power system. By dividing different power angle stability intervals, the present application can determine the appropriate time to take different control measures, so as to realize the timely execution of the control measures when the system power angle is unstable.

Description

Technical Field

[0001] This invention belongs to the field of power system security and stability analysis, and specifically relates to a method and system for dividing and controlling the power angle stability interval based on wide-area branch response. Background Technology

[0002] The safe and stable operation of a power grid depends on monitoring its stability. Accurately identifying the instability state and its timing is crucial for timely emergency control measures and restoring the grid to stable operation as quickly as possible. Regarding the power angle stability of the power grid, existing methods for analyzing and controlling its characteristics either target a single time interval during a disturbance, focus on a single characteristic state of the disturbed trajectory, or address specific control measures. Since the transition from a stable to an unstable state in a power system's power angle stability is a time-varying process, the control measures required at different stages of power angle stability also differ. Existing methods that apply a single control measure to a single power angle stability state suffer from control mismatch. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for dividing and controlling the power angle stability interval based on wide-area branch response, so as to solve the technical problem of control mismatch in the prior art where a single control measure is adopted for a single power angle stability state.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a method for dividing and controlling the power angle stability interval based on wide-area branch response, including:

[0006] Obtain the voltage amplitude U between nodes m and n on each branch i in the power system. mi U ni and voltage phase θ mi θ ni Calculate the branch transient transmission capacity index sBTTC for each branch. i and position coefficient ξ vi According to the branch transient transmission capacity index sBTTC i and position coefficient ξ vi Identify the critical branch k in the power system;

[0007] Based on the critical branch k, determine whether the power angle of the generator units in the power system is unstable; if the power angle of the generator units in the power system is determined to be unstable, proceed to the determination steps of the instability zone; otherwise, proceed to the determination steps of the emergency zone and the warning zone.

[0008] The steps for determining the instability zone are as follows: If the power system is determined to have entered the instability zone, disconnect the critical branch k from the power system;

[0009] The procedure for determining emergency zones and warning zones: If the power system is determined to have entered an emergency zone or warning zone, a portion of the generator power is cut off from the power system.

[0010] A further improvement of the present invention is that: the two nodes m and n on each branch i are the two endpoints of branch i.

[0011] A further improvement of this invention lies in: the branch transient transmission capacity index sBTTC i The calculation formula is:

[0012]

[0013] Position coefficient ξ vi The calculation formula is:

[0014]

[0015]

[0016] Among them, U mi U is the voltage magnitude at node m on branch i. ni Let θ be the voltage magnitude at node n on branch i. mi Let θ be the voltage phase at node m on branch i. ni θ represents the voltage phase at node n on branch i; mi -θ ni This represents the voltage phase difference between the two nodes of branch i.

[0017] A further improvement of this invention lies in: based on the branch transient transmission capacity index sBTTC i and position coefficient ξ vi In the step of identifying the critical branch k in the power system, the transient transmission capacity index sBTTC of each branch is calculated using formula (4). i The branches with the smallest transient transmission capacity index are sorted and identified as critical branches k.

[0018]

[0019] A further improvement of this invention is that the step of determining whether the power angle of the generator units in the power system is unstable based on the critical branch k; if the power angle of the generator units in the power system is determined to be unstable, the step of entering the instability zone; otherwise, the step of entering the emergency zone and the warning zone, specifically includes:

[0020] Determine whether the critical branch k satisfies equation (5):

[0021]

[0022] In equation (5), Δθk This represents the voltage phase difference between the two nodes of the critical branch k; if equation (5) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (5) is satisfied, further determine whether the critical branch k satisfies equation (6):

[0023]

[0024] In equation (6), P k This represents the active power transmitted by the critical branch k; if equation (6) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (6) is satisfied, further determine whether the critical branch k satisfies equation (7):

[0025]

[0026] In equation (7), Δf k The frequency difference between the two nodes of the critical branch k is indicated; if equation (7) is not satisfied, the determination steps for entering the emergency zone and the warning zone are performed; if equation (7) is satisfied, the power angle of the generator in the power system is determined to be unstable, and the determination steps for entering the instability zone are performed.

[0027] A further improvement of the present invention is that the step of determining the unstable region specifically includes:

[0028] Determine whether the critical branch k satisfies equation (9):

[0029] sBTTC k <ε asth (9)

[0030] Where, ε asth The threshold value for initiating the disconnection control; if equation (9) is satisfied, it is determined that the power system has entered the instability zone and the critical branch k is disconnected from the power system; if equation (9) is not satisfied, there is no risk of power angle instability in the power system at this moment.

[0031] A further improvement of the present invention is that the determination steps for the emergency zone and the warning zone specifically include:

[0032] Determine whether the critical branch k satisfies equation (8):

[0033] sBTTC k <ε acth (8)

[0034] Where, ε acth The threshold value for initiating corrective control and additional control; if equation (8) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (8) is satisfied, the critical branch Δθ within the time window width [t-dt,t] is selected. k , Δf kThe measurement sequence is obtained and polynomial fitting is performed to determine whether the critical branch k satisfies equation (12):

[0035]

[0036]

[0037] Δf k Ψ″(Δθ k )<0 (12)

[0038] If equation (12) is satisfied, it is determined that the current state of the power system has entered the emergency zone, and active additional control is applied at the moment when equation (12) is satisfied, cutting off a portion of the generator power from the current power system;

[0039] If equation (12) is not satisfied, it is determined that the current state of the power system has entered the warning zone, and active correction control is applied at the moment when equation (12) is not satisfied, and a portion of the generator power is cut off from the current power system.

[0040] Among them, the generator power cut off when entering the emergency zone is greater than the generator power cut off when entering the warning zone.

[0041] Secondly, the present invention provides a power angle stability interval division and control device based on wide-area branch response, comprising:

[0042] The critical branch identification module is used to obtain the voltage amplitude U between nodes m and n on each branch i in the power system. mi U ni and voltage phase θ mi θ ni Calculate the branch transient transmission capacity index sBTTC for each branch. i and position coefficient ξ vi According to the branch transient transmission capacity index sBTTC i and position coefficient ξ vi Identify the critical branch k in the power system;

[0043] The judgment module is used to determine whether the power angle of the generator units in the power system is unstable based on the critical branch k; if the power angle of the generator units in the power system is determined to be unstable, the judgment module enters the instability zone; otherwise, the judgment module enters the emergency zone and the warning zone.

[0044] The instability zone determination module is used to determine the instability zone: if the power system is determined to have entered the instability zone, the critical branch k is disconnected from the power system;

[0045] The emergency zone and warning zone determination module is used to determine whether the power system has entered an emergency zone or warning zone: if it is determined that the power system has entered an emergency zone or warning zone, a portion of the generator power is cut off from the power system.

[0046] Thirdly, the present invention provides an electronic device, including a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the power angle stability interval division and control method based on wide-area branch response.

[0047] Fourthly, the present invention provides a computer-readable storage medium storing at least one instruction, which, when executed by a processor, implements the power angle stability interval division and control method based on wide-area branch response.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] This invention provides a method and system for dividing and controlling the power angle stability interval based on wide-area branch response, which obtains the voltage amplitude U between two nodes m and n on each branch i in the power system. mi U ni and voltage phase θ mi θ ni Calculate the branch transient transmission capacity index sBTTC for each branch. i and position coefficient ξ vi According to the branch transient transmission capacity index sBTTC i and position coefficient ξ vi The invention identifies a critical branch k in the power system; determines whether the power angle of the generating units in the power system is unstable based on the critical branch k; if the power angle of the generating units in the power system is determined to be unstable, it proceeds to the determination step of the instability zone; otherwise, it proceeds to the determination steps of the emergency zone and the warning zone. When the power angle of the power system becomes unstable, this invention, on the one hand, can determine the appropriate time to take different control measures by dividing different power angle stability intervals, thereby realizing the timely execution of control measures when the system power angle is unstable; on the other hand, by formulating different control measures at different stages of system power angle stability, it avoids the situation where the control measures fail due to inadequacy or the control cost is too high.

[0050] This invention enables continuous monitoring of the power angle stability of the power grid after disturbance, and allows for multi-level prevention and control strategies based on the monitoring results. By designing different stability criteria for the power angle stability of the power grid according to the severity, it achieves accurate identification of the power angle stability of the power grid and divides different power angle stability intervals. Furthermore, it allows for different targeted control measures to be taken for power systems in different power angle stability intervals. Attached Figure Description

[0051] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0052] Figure 1 This is a flowchart illustrating a method for dividing and controlling the power angle stability interval based on wide-area branch response according to the present invention.

[0053] Figure 2 A schematic diagram of a typical system model for power angle stability analysis;

[0054] Figure 3 This is a schematic diagram of another power angle stability interval division and control method based on wide-area branch response according to the present invention;

[0055] Figure 4 This is a schematic diagram of a 10-machine, 39-node test system;

[0056] Figure 5 For B 16 -B 17 A schematic diagram of system power angle instability after a branch circuit fault is interrupted; where... Figure 5 (a) is a schematic diagram of the generator power angle difference; Figure 5 (b) is a schematic diagram of node voltages;

[0057] Figure 6 The curves show the sBTTC index and position coefficient of each branch during the power angle instability process; among them, Figure 6 (a) is a schematic diagram of the sBTTC index of each branch. Figure 6 (b) shows the location coefficient curves for each branch road;

[0058] Figure 7 For the critical branch Δθ k -P k , Δθ k -Δf k Trajectory curve; where, Figure 7 (a) is Δθ k -P k trajectory curve, Figure 7 (b) is Δθ k -Δf k trajectory curve;

[0059] Figure 8 This is a schematic diagram of the system response after implementing active correction control; where, Figure 8 (a) is a schematic diagram of the generator power angle difference after active correction control. Figure 8 (b) is a schematic diagram of the node voltage after active correction control;

[0060] Figure 9 This is a schematic diagram of the system response after implementing active additional control; where, Figure 9 (a) Schematic diagram of generator power angle difference after implementing active additional control. Figure 9 (b) Schematic diagram of node voltage after implementing active supplementary control;

[0061] Figure 10 To implement active additional control on the critical branch Δθ k -P k , Δθ k -Δf k Trajectory curve; where, Figure 10 (a) is Δθ k -P k trajectory curve, Figure 10 (b) is Δθ k -Δf k trajectory curve;

[0062] Figure 11 This is a schematic diagram of the system response after implementing active disconnection control; where, Figure 11 (a) is a schematic diagram of the generator power angle difference. Figure 11 (b) is a schematic diagram of node voltages; Figure 11 (c) is a schematic diagram of the node frequency difference;

[0063] Figure 12 This is a structural block diagram of a power angle stability interval division and control device based on wide-area branch response according to the present invention.

[0064] Figure 13 This is a schematic diagram of the structure of an electronic device according to the present invention. Detailed Implementation

[0065] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0066] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0067] The symbols to be used in this invention are as follows: Figure 1 As shown. U mi U is the voltage amplitude at node m on branch i. ni θ is the voltage magnitude at node n on branch i. mi θ is the voltage phase at node m on branch i. ni It is the voltage phase at node n on branch i; I i For branch current, b is the power factor angle. i r i and x iFor branch i, the susceptance, resistance, and reactance to ground are I. bi Let be the current flowing through branch i with respect to ground susceptance.

[0068] Example 1

[0069] Please see Figure 2 As shown, this invention provides a method for dividing and controlling the power angle stability interval based on wide-area branch response, including:

[0070] S1. Obtain the voltage amplitude U between nodes m and n on each branch i in the power system. mi U ni and voltage phase θ mi θ ni Calculate the branch transient transmission capacity index sBTTC for each branch. i and position coefficient ξ vi According to the branch transient transmission capacity index sBTTC i and position coefficient ξ vi Identify the critical branch k in the power system;

[0071] S2. Determine whether the power angle of the generator units in the power system is unstable based on the critical branch k; if the power angle of the generator units in the power system is determined to be unstable, proceed to the determination steps of the instability zone; otherwise, proceed to the determination steps of the emergency zone and the warning zone.

[0072] S3. Determination steps for the unstable zone: If the power system is determined to have entered the unstable zone, disconnect the critical branch k from the power system; Determination steps for the emergency zone and warning zone: If the power system is determined to have entered the emergency zone or warning zone, disconnect part of the generator power from the power system.

[0073] In one specific implementation, the two nodes m and n on each branch i are the two endpoints of branch i.

[0074] In one specific implementation, the branch transient transmission capacity index sBTTC i The calculation formula is:

[0075]

[0076] Position coefficient ξ vi The calculation formula is:

[0077]

[0078]

[0079] Among them, U mi U is the voltage magnitude at node m on branch i. ni Let θ be the voltage magnitude at node n on branch i. miLet θ be the voltage phase at node m on branch i. ni θ represents the voltage phase at node n on branch i; mi -θ ni This represents the voltage phase difference between the two nodes of branch i.

[0080] In one specific implementation, based on the branch transient transmission capacity index sBTTC i and position coefficient ξ vi In the step of identifying the critical branch k in the power system, the transient transmission capacity index sBTTC of each branch is calculated using formula (4). i The branches with the smallest transient transmission capacity index are sorted and identified as critical branches k.

[0081]

[0082] In one specific implementation, the step of determining whether the power angle of the generator units in the power system is unstable based on the critical branch k; if the power angle of the generator units in the power system is determined to be unstable, entering the instability zone; otherwise entering the emergency zone and the warning zone, specifically includes:

[0083] Determine whether the critical branch k satisfies equation (5):

[0084]

[0085] In equation (5), Δθ k This represents the voltage phase difference between the two nodes of the critical branch k; if equation (5) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (5) is satisfied, further determine whether the critical branch k satisfies equation (6):

[0086]

[0087] In equation (6), P k This represents the active power transmitted by the critical branch k; if equation (6) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (6) is satisfied, further determine whether the critical branch k satisfies equation (7):

[0088]

[0089] In equation (7), Δf k The frequency difference between the two nodes of the critical branch k is indicated; if equation (7) is not satisfied, the determination steps for entering the emergency zone and the warning zone are performed; if equation (7) is satisfied, the power angle of the generator in the power system is determined to be unstable, and the determination steps for entering the instability zone are performed.

[0090] In one specific embodiment, the step of determining the unstable region specifically includes:

[0091] Determine whether the critical branch k satisfies equation (9):

[0092] sBTTC k <ε asth (9)

[0093] Where, ε asth The threshold value for initiating the disconnection control; if equation (9) is satisfied, it is determined that the power system has entered the instability zone and the critical branch k is disconnected from the power system; if equation (9) is not satisfied, there is no risk of power angle instability in the power system at this moment.

[0094] In one specific implementation, the steps for determining the emergency zone and the warning zone specifically include:

[0095] Determine whether the critical branch k satisfies equation (8):

[0096] sBTTC k <ε acth (8)

[0097] Where, ε acth The threshold value for initiating corrective control and additional control; if equation (8) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (8) is satisfied, the critical branch Δθ within the time window width [t-dt,t] is selected. k , Δf k The measurement sequence is obtained and polynomial fitting is performed to determine whether the critical branch k satisfies equation (12):

[0098]

[0099]

[0100] Δf k Ψ″(Δθ k )<0 (12)

[0101] If equation (12) is satisfied, it is determined that the current state of the power system has entered the emergency zone, and active additional control is applied at the moment when equation (12) is satisfied, cutting off a portion of the generator power from the current power system to restore the power angle stability of the system;

[0102] If equation (12) is not satisfied, it is determined that the current state of the power system has entered the warning zone, and active correction control is applied at the moment when equation (12) is not satisfied, cutting off a portion of the generator power from the current power system to restore the power angle stability of the system.

[0103] Example 2

[0104] Please see Figure 3As shown, this invention provides a method for dividing and controlling the power angle stability interval based on wide-area branch response, including the following steps:

[0105] Step 1: Set the relevant parameters R, Δt, ε acth ε asth .

[0106] R is a parameter set by the user, representing the highest order of the polynomial set in equation (10);

[0107] Δt is a parameter set by the user, representing the time interval between two adjacent moments in each moment traversed by the present invention;

[0108] ε acth A parameter set manually, representing the threshold value for initiating corrective and supplementary control;

[0109] ε asth A manually set parameter representing the threshold value for initiating decoupling control, and requiring ε asth <ε acth .

[0110] Step 2: Measure the voltage amplitude U at nodes m and n at both ends of each branch i (i = 1, 2, 3, ..., N, where N represents the total number of branches in the system) in the power system. mi U ni and voltage phase θ mi θ ni The branch transient transmission capacity (sBTTC) index of each branch is calculated according to equation (1), and the location coefficient ξ of each branch is calculated according to equations (2) and (3). vi According to equation (4), sort and locate the key branches.

[0111]

[0112]

[0113]

[0114]

[0115] In equation (1), U mi U ni θ mi θ ni exist Figure 1 The values ​​are already marked. The subscripts m and n represent the locations of two measurement points on a line, usually at both ends of the line. θ mi -θ ni This represents the voltage phase difference between the two nodes of branch i.

[0116] In equation (2), U v The vertical voltage amplitude of the branch is represented by equation (3).

[0117] The sBTTC index of each branch is sorted according to equation (4). The branch with the smallest sBTTC index value is defined as the critical branch, and its branch number is denoted as k.

[0118] Step 3: Determine whether the critical branch satisfies equation (5).

[0119]

[0120] In equation (5), Δθ k This represents the voltage phase difference between the two nodes of the critical branch k. When there is a risk of power angle instability in the system, the power angle of the generator group in the system will show an increasing trend, and the voltage phase difference between the two nodes of the critical branch will increase accordingly, which satisfies equation (5); if equation (5) is not satisfied, it means that there is no risk of power angle instability in the system at this moment.

[0121] If satisfied, proceed to step four;

[0122] If the condition is not met, make t = t + Δt, and return to step two.

[0123] Step 4: Determine whether the critical branch satisfies equation (6).

[0124]

[0125] In equation (6), P k This represents the active power transmitted in the critical branch k. As the power angle between generator groups further increases, the voltage drop at the nodes at both ends of the critical branch increases. When the effect of voltage drop in suppressing power transmission begins to outweigh the effect of increasing power transmission due to the increased phase difference, the active power P transmitted in the critical branch... k The phase difference Δθ between the voltages at both ends will change. k If the voltage phase difference between the two nodes increases and decreases, the system will have a risk of power angle instability, which means that equation (6) is satisfied. If equation (6) is not satisfied, it means that at this moment, as the voltage phase difference between the two nodes increases, the active power of the key branch can still maintain growth and send the surplus power to the receiving end, and the system will not have a risk of power angle instability.

[0126] If satisfied, proceed to step five;

[0127] If the condition is not met, the system is determined to be in a safe zone, so that t = t + Δt, and returns to step two.

[0128] Step 5: Determine whether the critical branch satisfies equation (7).

[0129]

[0130] In equation (7), Δf k Let represent the frequency difference between the nodes at both ends of the critical branch k. If equation (7) is satisfied, it means that at this moment, as the voltage phase difference between the nodes at both ends of the critical branch increases due to the increase in the power angle of the generator group, the frequency difference between the nodes at both ends of the critical branch continues to increase, indicating that the power angle of the generators at both ends of the critical branch is unstable and the judgment process of entering the unstable zone needs to be entered. If equation (7) is not satisfied, it means that the frequency difference between the nodes at both ends of the critical branch continues to decrease, indicating that the power angle stability of the system tends to deteriorate but still has a margin, and the judgment process of entering the emergency zone and the warning zone is entered.

[0131] If satisfied, proceed to step seven;

[0132] If the conditions are not met, proceed to step six.

[0133] Step 6: Determine whether the critical branch satisfies equation (8).

[0134] sBTTC k <ε acth (8)

[0135] If satisfied, proceed to step eight;

[0136] If the condition is not met, make t = t + Δt, and return to step two.

[0137] Step 7: Determine whether the critical branch satisfies equation (9).

[0138] sBTTC k <ε asth (9)

[0139] If satisfied, the system is determined to have entered the unstable region, and active disconnection control is applied at the moment when equation (9) is satisfied, that is, the critical branch k is disconnected from the current power system;

[0140] If the condition is not met, make t = t + Δt, and return to step two.

[0141] Step 8: Extract the critical branch Δθ within the time window width [t-dt,t]. k , Δf k The measurement sequence is obtained and polynomial fitting is performed to determine whether the key branch satisfies equation (12).

[0142]

[0143]

[0144] Δf k Ψ″(Δθ k )<0 (12)

[0145] Equation (10) represents the Δf of the critical branch. k -Δθ k The curve is fitted with a polynomial, where C r For each order of constant coefficients; Equation (11) is Ψ(Δθ) k The second derivative of Δf represents the second derivative of Δf. k -Δθ k The concavity or convexity of the curve, if Δf k Ψ″(Δθ k If the phase frequency response trajectory is less than 0, it exhibits concave characteristics; otherwise, it exhibits convex characteristics. The critical branch Δf is considered when the system's power angle is stable. k -Δθ k The curve should have concave characteristics, and the critical branch Δf should be observed when the system experiences power angle instability. k -Δθ k The curve will exhibit a "concave to convex" characteristic. Therefore, equation (12) can be used as a criterion for whether the system's power angle stability deteriorates.

[0146] If equation (12) is satisfied, it is determined that the current state of the power system has entered the emergency zone, and active additional control is applied at the moment when equation (12) is satisfied, cutting off a portion of the generator power from the current power system;

[0147] If equation (12) is not satisfied, it is determined that the current state of the power system has entered the warning zone, and active correction control is applied at the moment when equation (12) is not satisfied, cutting off a portion of the generator power from the current power system.

[0148] Example 3

[0149] Build such a system in power system transient simulation software Figure 4 The 10-machine, 39-node test system shown includes a connection branch B between region A and region C. 16 -B 17 After the fault is interrupted, the units in Area A and the main grid will experience power angle instability. Furthermore, during the power angle adjustment process, there is a risk that the units in Area B will successively become unstable, thus expanding the scope of the disturbance.

[0150] Set R = 2, Δt = 0.02s, ε acth =0.5, ε asth =0.25; set in B 16 -B 17 Branch Road B 16 A three-phase permanent short circuit lasting 0.26 seconds occurs at the node side at 0.2 seconds, clearing the disturbance of the faulty branch. The transient responses of the power angle and node voltage of all units in the system, with G9 as the reference unit, are as follows: Figure 5 As shown, the system will experience power angle instability at this time, and the voltage of each branch node will also show an oscillating instability trend due to the power angle instability.

[0151] Corresponding to the above-mentioned power angle instability process, the amplitude and phase of the voltage at both ends of each branch in the system at each time are read by the wide-area measurement system, and the sBTTC index of each AC branch in the system and the position coefficient ξ of each branch are calculated according to equations (1)-(3). v The result is as follows Figure 6 As shown, the critical branch obtained by sorting according to equation (4) is B. 14 -B 15 .

[0152] Read the critical branch B using a wide-range measurement system 14 -B 15 The phase difference Δθ between the two node voltages at each time point k Frequency difference Δf between the two nodes k Branch active power P k , can obtain as Figure 7 The key branch Δθ shown k -P k , Δθ k -Δf k Trajectory curve. Combined with Figure 7 And the relevant processes of equations (5)-(7) can determine and divide the stable range of the power angle: S bpmax This represents the characteristic state point where the active power of the critical branch reaches its maximum value, during which... This corresponds to the safe zone; S bconv Represents the critical branch Δθ k -Δf k The characteristic state point where the concavity and convexity of the curve change, corresponding to equation (12), is the dividing point between the warning zone and the emergency zone; S bust Represents the critical branch Δθ k -Δf k The characteristic state point where the monotonicity of the curve changes, corresponding to equation (7), is the node for dividing the unstable region.

[0153] From the time the disturbance was cleared until 2.64 seconds later, critical branch B 14 -B 15 If equation (5) is satisfied but equation (6) is not, the system's power angle stability is in the safe zone. After 2.64s, the critical branch does not satisfy equation (7), satisfies equation (8), and does not satisfy equation (12), so the system's power angle stability has entered the warning zone, and therefore active correction control can be initiated. Considering a 0.2s communication and control delay, the generator G5 power of 300MW is cut off at 2.84s. The transient response of the system after the control is implemented is as follows: Figure 8 As shown, it can be seen that taking active correction control measures at the time determined by this method can restore the system to power angle stability.

[0154] If active correction control is not implemented in the warning zone, the system stability will tend to deteriorate further as the power angle difference between generator groups increases, and the critical branch will satisfy equation (12) at 3.32s, at which point the system power angle stability state will enter the emergency zone. Considering a 0.2s communication and control delay, active supplementary control is implemented at 3.52s to cut off the power of generators G4 and G5 by 300MW each. The system transient response is as follows: Figure 9 As shown, since the system state is very close to instability at this point, and control measures cannot restore system stability, it is necessary to further implement active disconnection control on top of applying additional active control.

[0155] With active additional control implemented in the system, the sBTTC index, location coefficient, and critical branch Δθ of each branch in the system are measured. k -P k , Δθ k -Δf k The trajectory curves will all change. After recalculation, the new critical branch is determined to be B. 14 -B 15 And obtain the new critical branch Δθ k -P k , Δθ k -Δf k trajectory curve as Figure 10 As shown.

[0156] according to Figure 10 At 4.8s, the critical branch satisfies equations (7) and (9), and the system enters the unstable region in the power angle stable state. Considering the 0.2s communication and control delay, active disconnection control is implemented at 5.0s, and the critical branch B is disconnected. 14 -B 15 System transient response such as Figure 11 As shown in the figure, it can be seen that taking active supplementary control and active disconnection control measures at the time determined by this method can restore the system to power angle stability, thus verifying the accuracy and effectiveness of this method in dividing the system's power angle stability interval.

[0157] Example 4

[0158] Please see Figure 12 As shown, the present invention provides a power angle stability interval division and control device based on wide-area branch response, comprising:

[0159] The critical branch identification module is used to obtain the voltage amplitude U between nodes m and n on each branch i in the power system. mi U ni and voltage phase θ mi θ ni Calculate the branch transient transmission capacity index sBTTC for each branch. iand position coefficient ξ vi According to the branch transient transmission capacity index sBTTC i and position coefficient ξ vi Identify the critical branch k in the power system;

[0160] The judgment module is used to determine whether the power angle of the generator units in the power system is unstable based on the critical branch k; if the power angle of the generator units in the power system is determined to be unstable, the judgment module enters the instability zone; otherwise, the judgment module enters the emergency zone and the warning zone.

[0161] The instability zone determination module is used to determine the instability zone: if the power system is determined to have entered the instability zone, the critical branch k is disconnected from the power system;

[0162] The emergency zone and warning zone determination module is used to determine whether the power system has entered an emergency zone or warning zone: if it is determined that the power system has entered an emergency zone or warning zone, a portion of the generator power is cut off from the power system.

[0163] In one specific implementation, the two nodes m and n on each branch i are the two endpoints of branch i.

[0164] In one specific implementation, the branch transient transmission capacity index sBTTC i The calculation formula is:

[0165]

[0166] Position coefficient ξ vi The calculation formula is:

[0167]

[0168]

[0169] Among them, U mi U is the voltage amplitude at node m on branch i. ni Let θ be the voltage magnitude at node n on branch i. mi Let θ be the voltage phase at node m on branch i. ni θ represents the voltage phase at node n on branch i; mi -θ ni This represents the voltage phase difference between the two nodes of branch i.

[0170] In one specific implementation, the critical branch identification module identifies the branch based on the branch transient transmission capacity index sBTTC. i and position coefficient ξ vi In the step of identifying the critical branch k in the power system, the transient transmission capacity index sBTTC of each branch is calculated using formula (4). iThe branches with the smallest transient transmission capacity index are sorted and identified as critical branches k.

[0171]

[0172] In one specific implementation, the judgment module determines whether the power angle of the generator units in the power system is unstable based on the critical branch k; if the power angle of the generator units in the power system is determined to be unstable, the judgment enters the instability zone; otherwise, the judgment enters the emergency zone and the warning zone, specifically including:

[0173] Determine whether the critical branch k satisfies equation (5):

[0174]

[0175] In equation (5), Δθ k This represents the voltage phase difference between the two nodes of the critical branch k; if equation (5) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (5) is satisfied, further determine whether the critical branch k satisfies equation (6):

[0176]

[0177] In equation (6), P k This represents the active power transmitted by the critical branch k; if equation (6) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (6) is satisfied, further determine whether the critical branch k satisfies equation (7):

[0178]

[0179] In equation (7), Δf k The frequency difference between the two nodes of the critical branch k is indicated; if equation (7) is not satisfied, the determination steps for entering the emergency zone and the warning zone are performed; if equation (7) is satisfied, the power angle of the generator in the power system is determined to be unstable, and the determination steps for entering the instability zone are performed.

[0180] In one specific implementation, the determination of the instability zone specifically includes:

[0181] Determine whether the critical branch k satisfies equation (9):

[0182] sBTTC k <ε asth (9)

[0183] Where, ε asth The threshold value for initiating the disconnection control; if equation (9) is satisfied, it is determined that the power system has entered the instability zone and the critical branch k is disconnected from the power system; if equation (9) is not satisfied, there is no risk of power angle instability in the power system at this moment.

[0184] In one specific implementation, the determination of emergency zones and restricted zones specifically includes:

[0185] Determine whether the critical branch k satisfies equation (8):

[0186] sBTTC k <ε acth (8)

[0187] Where, ε acth The threshold value for initiating corrective control and additional control; if equation (8) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (8) is satisfied, the critical branch Δθ within the time window width [t-dt,t] is selected. k , Δf k The measurement sequence is obtained and polynomial fitting is performed to determine whether the critical branch k satisfies equation (12):

[0188]

[0189]

[0190] Δf k Ψ″(Δθ k )<0 (12)

[0191] If equation (12) is satisfied, it is determined that the current state of the power system has entered the emergency zone, and active additional control is applied at the moment when equation (12) is satisfied, cutting off a portion of the generator power from the current power system;

[0192] If equation (12) is not satisfied, it is determined that the current state of the power system has entered the warning zone, and active correction control is applied at the moment when equation (12) is not satisfied, cutting off a portion of the generator power from the current power system.

[0193] Example 5

[0194] Please see Figure 13 As shown, the present invention also provides an electronic device 100 for implementing a power angle stability interval division and control method based on wide-area branch response; the electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on the at least one processor 102, and at least one communication bus 104.

[0195] The memory 101 can be used to store the computer program 103. The processor 102 implements the steps of the power angle stability interval division and control method based on wide-area branch response described in Embodiment 1 or 2 by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101. The memory 101 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device 100 (such as audio data), etc. In addition, the memory 101 may include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other non-volatile solid-state storage device.

[0196] The at least one processor 102 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 102 may be a microprocessor or any conventional processor. The processor 102 is the control center of the electronic device 100, connecting various parts of the electronic device 100 via various interfaces and lines.

[0197] The memory 101 in the electronic device 100 stores multiple instructions to implement a power angle stability interval division and control method based on wide-area branch response, and the processor 102 can execute the multiple instructions to achieve the following:

[0198] Obtain the voltage amplitude U between nodes m and n on each branch i in the power system. mi U ni and voltage phase θ mi θ ni Calculate the branch transient transmission capacity index sBTTC for each branch. i and position coefficient ξ vi According to the branch transient transmission capacity index sBTTC iand position coefficient ξ vi Identify the critical branch k in the power system;

[0199] Based on the critical branch k, determine whether the power angle of the generator units in the power system is unstable; if the power angle of the generator units in the power system is determined to be unstable, proceed to the determination steps of the instability zone; otherwise, proceed to the determination steps of the emergency zone and the warning zone.

[0200] The steps for determining the instability zone are as follows: If the power system is determined to have entered the instability zone, disconnect the critical branch k from the power system;

[0201] The procedure for determining emergency zones and warning zones: If the power system is determined to have entered an emergency zone or warning zone, a portion of the generator power is cut off from the power system.

[0202] Example 6

[0203] If the modules / units integrated in the electronic device 100 are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, and a read-only memory (ROM).

[0204] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0205] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0206] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0207] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0208] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for dividing and controlling the power angle stability interval based on wide-area branch response, characterized in that, include: Obtain every branch in the power system i Voltage amplitudes at the two nodes m and n , and voltage phase , Calculate the transient transmission capacity index of each branch. and position coefficient According to the transient transmission capacity index of the branch line and position coefficient Identify critical branches in the power system k ; Based on key branches k Determine whether the power angle of the generator units in the power system is unstable; if the power angle of the generator units in the power system is determined to be unstable, proceed to the determination steps of the instability zone; otherwise, proceed to the determination steps of the emergency zone and the warning zone. The steps for determining the instability zone are as follows: If the power system is determined to have entered the instability zone, disconnect the critical branches from the power system. k ; The procedure for determining emergency zones and warning zones: If it is determined that the power system has entered an emergency zone or warning zone, a portion of the generator power is cut off from the power system; According to the critical branch k The process involves determining whether the power angle of generating units in the power system is unstable. If the power angle is determined to be unstable, the process proceeds to the instability zone determination steps. Otherwise, the process proceeds to the emergency zone and the warning zone determination steps, specifically including: Determine whether the critical branch k satisfies equation (5): （5） In equation (5), Indicates the critical branch k The voltage phase difference between the two nodes; if equation (5) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (5) is satisfied, further judgment of the critical branch. k Does it satisfy equation (6)? （6） In equation (6), Indicates the critical branch k The transmitted active power; if equation (6) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (6) is satisfied, further judgment is made on the critical branch. k Does it satisfy equation (7)? （7） In equation (7), Indicates the critical branch k Frequency difference between the two nodes; if equation (7) is not satisfied, the determination steps for entering the emergency zone and the warning zone; if equation (7) is satisfied, the determination steps for entering the instability zone of the generator unit in the power system are determined. The steps for determining the unstable region specifically include: Determine the critical branch k Does it satisfy equation (9)? （9） in, The threshold value for initiating disconnection control; if equation (9) is satisfied, it is determined that the power system has entered the instability zone, and the critical branch is disconnected from the power system at the moment when equation (9) is satisfied. k If equation (9) is not satisfied, there is no risk of power angle instability in the power system at this moment. The specific steps for determining the emergency zone and the restricted zone include: Determine the critical branch k Does it satisfy equation (8)? （8） in, The threshold values ​​for initiating corrective and supplementary control. If equation (8) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (8) is satisfied, the time window width is truncated. Internal critical branch , The measurement sequence is obtained and polynomial fitting is performed to determine the critical branches. k Does it satisfy equation (12)? （10） （11） （12） If equation (12) is satisfied, it is determined that the current state of the power system has entered the emergency zone, and active additional control is applied at the moment when equation (12) is satisfied, and a portion of the generator power is cut off from the current power system; If equation (12) is not satisfied, it is determined that the current state of the power system has entered the warning zone, and active correction control is applied at the moment when equation (12) is not satisfied, and a portion of the generator power is cut off from the current power system; wherein, the generator power cut off when entering the emergency zone is greater than the generator power cut off when entering the warning zone.

2. The method for dividing and controlling the power angle stability interval based on wide-area branch response according to claim 1, characterized in that, Every branch road i The two nodes m and n are branches. i The two endpoints.

3. The method for dividing and controlling the power angle stability interval based on wide-area branch response according to claim 1, characterized in that, Branch transient transmission capacity index The calculation formula is: （1） Position coefficient The calculation formula is: （2） （3） in, branch road i The voltage amplitude at node m, branch road i The voltage amplitude at node n, branch road i The voltage phase at node m, branch road i The voltage phase at node n; Indicates a branch i The voltage phase difference between the two nodes.

4. The method for dividing and controlling the power angle stability interval based on wide-area branch response according to claim 3, characterized in that, According to the branch transient transmission capacity index and position coefficient Identify critical branches in the power system k In the steps, the transient transmission capacity index of each branch is calculated using formula (4). The branches with the smallest transient transmission capacity index are ranked and identified as critical branches. k : （4）。 5. A power angle stability interval division and control device based on wide-area branch response, characterized in that, include: The critical branch identification module is used to acquire information about each branch in the power system. i Voltage amplitudes at the two nodes m and n , and voltage phase , Calculate the transient transmission capacity index of each branch. and position coefficient According to the transient transmission capacity index of the branch line and position coefficient Identify critical branches in the power system k ; The decision module is used to determine the critical branch. k Determine whether the power angle of the generating units in the power system is unstable; if the power angle of the generating units in the power system is determined to be unstable, determine whether to enter the instability zone; otherwise, determine whether to enter the emergency zone and the warning zone. The instability zone determination module is used to determine the instability zone: if the power system is determined to have entered the instability zone, the critical branch is disconnected from the power system. k ; The emergency zone and warning zone determination module is used to determine whether the power system has entered an emergency zone or warning zone: if it is determined that the power system has entered an emergency zone or warning zone, a portion of the generator power is cut off from the power system. According to the critical branch k The process involves determining whether the power angle of generating units in the power system is unstable. If the power angle is determined to be unstable, the process proceeds to the instability zone determination steps. Otherwise, the process proceeds to the emergency zone and the warning zone determination steps, specifically including: Determine whether the critical branch k satisfies equation (5): （5） In equation (5), Indicates the critical branch k The voltage phase difference between the two nodes; if equation (5) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (5) is satisfied, further judgment of the critical branch. k Does it satisfy equation (6)? （6） In equation (6), Indicates the critical branch k The transmitted active power; if equation (6) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (6) is satisfied, further judgment is made on the critical branch. k Does it satisfy equation (7)? （7） In equation (7), Indicates the critical branch k Frequency difference between the two nodes; if equation (7) is not satisfied, the determination steps for entering the emergency zone and the warning zone; if equation (7) is satisfied, the determination steps for entering the instability zone of the generator unit in the power system are determined. The steps for determining the unstable region specifically include: Determine the critical branch k Does it satisfy equation (9)? （9） in, The threshold value for initiating disconnection control; if equation (9) is satisfied, it is determined that the power system has entered the instability zone, and the critical branch is disconnected from the power system at the moment when equation (9) is satisfied. k If equation (9) is not satisfied, there is no risk of power angle instability in the power system at this moment. The specific steps for determining the emergency zone and the restricted zone include: Determine the critical branch k Does it satisfy equation (8)? （8） in, The threshold values ​​for initiating corrective and supplementary control. If equation (8) is not satisfied, there is no risk of power angle instability in the power system at this moment; if equation (8) is satisfied, the time window width is truncated. Internal critical branch , The measurement sequence is obtained and polynomial fitting is performed to determine the critical branches. k Does it satisfy equation (12)? （10） （11） （12） If equation (12) is satisfied, it is determined that the current state of the power system has entered the emergency zone, and active additional control is applied at the moment when equation (12) is satisfied, and a portion of the generator power is cut off from the current power system; If equation (12) is not satisfied, it is determined that the current state of the power system has entered the warning zone, and active correction control is applied at the moment when equation (12) is not satisfied, and a portion of the generator power is cut off from the current power system; wherein, the generator power cut off when entering the emergency zone is greater than the generator power cut off when entering the warning zone.

6. An electronic device, characterized in that, It includes a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the power angle stability interval division and control method based on wide-area branch response as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction, which, when executed by a processor, implements the power angle stability interval division and control method based on wide-area branch response as described in any one of claims 1 to 4.

Images