Protection method for concurrent faults and relay protection device

Abstract

The application provides a concurrent fault protection method and a relay protection device, which are applied to a power supply and distribution system. The power supply and distribution system comprises M incoming lines, M bus sections, N outgoing lines and M-1 bus section couplings, wherein M>=1, N>=2, N>M, and the method comprises the following steps: setting the concurrent fault protection of the incoming line relay protection device to an input state, and the outgoing line relay protection device collects the currents flowing through the multiple outgoing lines; when it is detected that the currents and direction elements of a plurality of outgoing lines meet preset conditions, it is determined that the plurality of outgoing lines are concurrent fault outgoing lines, and the concurrent fault states of the concurrent fault outgoing lines are obtained; based on the concurrent fault state, the fault duration and a preset concurrent fault delay setting value, the outgoing line relay protection device adopts a concurrent fault logic judgment mode to control the outgoing line breakers corresponding to the concurrent fault outgoing lines to trip, so as to isolate the concurrent fault outgoing lines. The application can accurately remove the electrical concurrent fault outgoing lines and avoid the forced power loss of the non-fault outgoing lines.

Description

Technical Field

[0001] This application belongs to the field of fault handling technology for power grid power supply and distribution systems, and particularly relates to a protection method and relay protection device for concurrent faults. Background Technology

[0002] Currently, relay protection, as the first line of defense for power transmission and distribution safety, requires selectivity, speed, sensitivity, and reliability in the event of electrical accidents to ensure the safety of the large power grid and normal power supply for users. Existing technologies handle accidents by coordinating upstream and downstream bay settings to ensure the sequence of line disconnections in various scenarios, which can meet the needs of most single outgoing line bay faults. However, in Southeast Asian countries, a common power outage phenomenon occurs when multiple outgoing lines fail to meet their operating conditions, while incoming lines do, causing priority tripping and forcing even fault-free outgoing lines to lose power. Therefore, for situations with concurrent faults on multiple outgoing lines, traditional setting coordination alone is insufficient to meet the selectivity and speed requirements for accurately disconnecting faulty outgoing lines.

[0003] Therefore, traditional relay protection technology solutions have the problem of not being able to accurately disconnect the electrical faulty outgoing line when multiple outgoing lines experience simultaneous faults (SF), resulting in the outgoing lines without faults also being forced to lose power. Summary of the Invention

[0004] The purpose of this application is to provide a method and device for protecting against concurrent faults, which aims to solve the problem that traditional relay protection cannot accurately disconnect electrical faulty outgoing lines, resulting in the forced power loss of even fault-free outgoing lines.

[0005] The first aspect of this application provides a method for protecting against concurrent faults, applied to a power supply and distribution system, the power supply and distribution system including M incoming lines, M bus sections, N outgoing lines and M-1 bus tie sections, wherein M≧1, N≧2, N>M;

[0006] Each incoming line is connected to the busbar via an incoming line circuit breaker, each section of the busbar is connected to the corresponding multiple outgoing lines via an outgoing line circuit breaker, and two sections of the busbar are connected by a bus tie sectionalizing circuit breaker.

[0007] The incoming circuit breaker is equipped with an incoming line relay protection device, the outgoing circuit breaker is equipped with an outgoing line relay protection device, and the bus tie sectional circuit breaker is equipped with a bus tie sectional relay protection device.

[0008] The concurrent fault protection method includes:

[0009] The incoming line relay protection device is set to the concurrent fault protection enabled state;

[0010] The outgoing line relay protection device collects the current flowing through multiple outgoing lines respectively;

[0011] When multiple outgoing line relay protection devices simultaneously detect that the current and direction elements of several outgoing lines meet preset conditions, the outgoing line relay protection devices determine that several outgoing lines are concurrent fault outgoing lines and obtain the concurrent fault status of each concurrent fault outgoing line.

[0012] Based on the concurrent fault status, the fault duration, and the preset concurrent fault delay setting, the outgoing line relay protection device uses a concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip, so as to isolate each concurrent fault outgoing line.

[0013] In one embodiment,

[0014] Before the step of setting the relay protection device of each of the incoming lines to the concurrent fault protection enabled state, the method further includes:

[0015] Based on the power supply and distribution system parameters and the preset upstream and downstream coordination principle, the protection settings for phase overcurrent of the outgoing line and the bus tie section are set respectively, and the protection settings for zero-sequence overcurrent of the outgoing line and the bus tie section are set respectively.

[0016] In one embodiment,

[0017] The protection settings include at least one of the following: current setting, delay curve, delay setting, and direction element setting.

[0018] In one embodiment,

[0019] The preset conditions include a first preset condition;

[0020] The preset first condition is:

[0021] The current of each of the several outgoing lines is greater than or equal to the preset phase overcurrent current setting of the outgoing line;

[0022] Furthermore, the directional element is defined as flowing from the busbar to the line in the positive direction. The directional element adopts a 90° connection, i.e., Ia→Ubc / Ib→Uca / Ic→Uab. The positive direction operation equation is:

[0023]

[0024] in, This refers to the polarization phase current;

[0025] This refers to the polarization phase-to-phase voltage;

[0026] e is the base of the exponential function;

[0027] j is the imaginary unit of the exponential function in the complex plane;

[0028] RCA is the characteristic angle of the device.

[0029] In one embodiment,

[0030] The preset conditions also include a preset second condition;

[0031] The preset second condition is:

[0032] The current of each of the several outgoing lines is greater than or equal to the preset zero-sequence overcurrent current value of the outgoing line.

[0033] Furthermore, the directional element is defined as flowing from the busbar to the line in the positive direction. The directional element adopts a 0° connection, i.e., I0-(-U0), and the positive direction operation equation is:

[0034]

[0035] in, The zero-sequence current is polarized;

[0036] The zero-sequence voltage of polarization;

[0037] e is the base of the exponential function;

[0038] j is the imaginary unit of the exponential function in the complex plane;

[0039] RCA is the characteristic angle of the device.

[0040] In one embodiment,

[0041] The concurrent fault state includes the concurrent fault first state;

[0042] The first state of concurrent failure includes:

[0043] The bus tie section circuit breaker is in the open position;

[0044] Each of the aforementioned concurrent fault outgoing lines is connected to the same concurrent fault bus.

[0045] In one embodiment,

[0046] The concurrent fault state also includes a concurrent fault second state;

[0047] The second concurrent failure state includes:

[0048] The bus tie section circuit breaker is in the closed position;

[0049] Each of the aforementioned concurrent fault outgoing lines is connected to at least two of the aforementioned concurrent fault busbars;

[0050] The bus tie section relay protection device determines that the current flowing through the bus tie section between each of the concurrent fault buses is greater than or equal to the preset phase overcurrent current setting of the bus tie section, or determines that the current flowing through the bus tie section between each of the concurrent fault buses is greater than or equal to the preset zero-sequence overcurrent current setting of the bus tie section.

[0051] In one embodiment, based on the concurrent fault state, the fault duration, and a preset concurrent fault delay setting, the outgoing line relay protection device uses a concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip, including:

[0052] Based on the concurrent fault state, the fault duration, and the preset concurrent fault delay setting, the outgoing line relay protection device uses a distributed concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip.

[0053] The distributed concurrent fault logic judgment method includes:

[0054] Each of the outgoing line relay protection devices receives the concurrent fault protection activation / deactivation signal sent by each of the incoming line relay protection devices;

[0055] If the concurrent fault protection enable / disable signal is in the concurrent fault protection enable state, and based on the concurrent fault state, the outgoing line relay protection device corresponding to each concurrent fault outgoing line respectively times the fault duration of the concurrent fault outgoing line;

[0056] If the duration of the concurrent fault outgoing line is greater than or equal to the preset concurrent fault delay setting, the outgoing line relay protection device of each concurrent fault outgoing line outputs an output signal to the corresponding connected outgoing line circuit breaker to trip.

[0057] In one embodiment, the outgoing line relay protection device, based on the concurrent fault state, the fault duration, and a preset concurrent fault delay setting, controls the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip using a concurrent fault logic judgment method, further includes:

[0058] Based on the concurrent fault status, the fault duration, and the preset concurrent fault delay setting, the outgoing line relay protection device uses a centralized concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip.

[0059] The centralized concurrent fault logic judgment method includes:

[0060] The bus tie section relay protection device receives concurrent fault protection activation / deactivation signals sent by each of the corresponding connected incoming line relay protection devices;

[0061] If the concurrent fault protection enable / disable signal indicates that the concurrent fault protection is enabled, and based on the concurrent fault status, the bus tie section relay protection device counts the duration of the fault for each of the concurrent fault outgoing lines.

[0062] If the duration of the concurrent fault outgoing line is greater than or equal to the preset concurrent fault delay setting, the bus tie section relay protection device sends a trip signal to the outgoing line relay protection device corresponding to each concurrent fault outgoing line.

[0063] Each of the outgoing line relay protection devices that cause concurrent faults receives the trip signal and outputs an output signal to the corresponding connected outgoing line circuit breaker to trip the circuit breaker.

[0064] The second aspect of this application provides a relay protection device for concurrent faults, applied to a power supply and distribution system, including: an analog quantity acquisition module, an input quantity acquisition module, an output quantity module, a memory, a processor, and a computer program stored in the memory and executable on the processor;

[0065] The analog quantity acquisition module is used to acquire analog quantities of the power supply and distribution system and output them to the processor;

[0066] The input signal acquisition module is used to acquire the input signal of the power supply and distribution system and transmit it to the processor;

[0067] The output module is used to send the output signal from the processor;

[0068] When the processor executes the computer program, it implements the steps of the method as described in any of the first aspects.

[0069] The beneficial effects of the embodiments in this application compared with the prior art are:

[0070] This application provides a method and relay protection device for concurrent fault protection in power supply and distribution systems. The method involves setting the relay protection devices on each incoming line to a concurrent fault protection enabled state. The outgoing line relay protection devices identify outgoing lines whose current and direction elements meet preset conditions as concurrent fault outgoing lines, and acquire the concurrent fault status of each outgoing line. Based on the concurrent fault status, fault duration, and preset concurrent fault delay setting, the outgoing line relay protection devices use a concurrent fault logic judgment method to control the corresponding outgoing line circuit breaker to trip, thereby isolating each concurrent fault outgoing line. The concurrent fault method provided in this application can quickly and accurately disconnect each outgoing line with concurrent overcurrent faults when multiple outgoing lines experience concurrent overcurrent faults, preventing fault-free outgoing lines from being disconnected, thus minimizing the scope of power loss and reducing the impact of power outages on society. Attached Figure Description

[0071] Figure 1 A schematic flowchart illustrating a concurrent fault protection method provided in an embodiment of this application;

[0072] Figure 2 A wiring diagram of a power supply and distribution system provided in one embodiment of this application;

[0073] Figure 3 Based on Figure 2 A schematic diagram of a single-line power supply and distribution system;

[0074] Figure 4 This is a schematic diagram illustrating the enabling / disabling of concurrent fault protection logic for any incoming line in one embodiment of this application;

[0075] Figure 5 This is a schematic diagram of the concurrent fault protection activation process for any outgoing line in one embodiment of this application;

[0076] Figure 6 This is a schematic diagram of a concurrent fault in outgoing lines 1 and 2 in one embodiment of this application;

[0077] Figure 7 This is a schematic diagram of a concurrent fault of outgoing lines 1 and 6 in one embodiment of this application;

[0078] Figure 8 This is a schematic diagram illustrating the activation of concurrent fault protection for the bus tie segment in one embodiment of this application;

[0079] Figure 9 This is a schematic diagram of the concurrent fault protection activation of incoming line 2 in one embodiment of this application;

[0080] Figure 10 This is a schematic diagram of the concurrent fault tripping logic judgment process for any outgoing line in one embodiment of this application;

[0081] Figure 11 A schematic diagram of the concurrent fault module connection of output line 1 in a distributed concurrent fault logic judgment method provided in an embodiment of this application;

[0082] Figure 12 This is a schematic diagram of the connection of the concurrent fault module in the bus joint segment in a centralized concurrent fault logic judgment method provided in an embodiment of this application. Detailed Implementation

[0083] Traditional overcurrent protection schemes, when dealing with overcurrent faults on a single outgoing line, only protect the line itself and adjacent lines. However, in actual operation of power distribution systems, when overcurrent faults occur on two or more outgoing lines, incoming lines may trip before outgoing lines, failing to accurately isolate the faulty outgoing line and thus amplifying the impact of power loss.

[0084] Figure 1 A flowchart illustrating a concurrent fault protection method provided in this embodiment is shown. For ease of explanation, only the parts relevant to this embodiment are shown.

[0085] The present application will be further described below with reference to embodiments:

[0086] The first aspect of this application provides a method for protecting against concurrent faults, applied to a power supply and distribution system. The power supply and distribution system includes M incoming lines, M bus sections, N outgoing lines, and M-1 bus tie sections, wherein M≧1, N≧2, and N>M. Each incoming line is connected to the bus via an incoming line circuit breaker, and each bus section is connected to the corresponding multiple outgoing lines via an outgoing line circuit breaker. Two bus sections are connected by a bus tie section circuit breaker. Each incoming line circuit breaker is equipped with an incoming line relay protection device, each outgoing line circuit breaker is equipped with an outgoing line relay protection device, and each bus tie section circuit breaker is equipped with a bus tie section relay protection device.

[0087] This embodiment provides a method for protecting against concurrent faults in a power supply and distribution system. The method involves setting the relay protection devices on each incoming line to a concurrent fault protection enabled state. The outgoing line relay protection devices identify outgoing lines whose current and direction elements meet preset conditions as concurrent fault outgoing lines, and acquire the concurrent fault status of each outgoing line. Based on the concurrent fault status, fault duration, and preset concurrent fault delay setting, the outgoing line relay protection devices use a concurrent fault logic judgment method to control the corresponding outgoing line circuit breaker to trip, thereby isolating each concurrent fault outgoing line. This concurrent fault method can quickly and accurately disconnect each outgoing line with concurrent overcurrent faults when multiple outgoing lines experience concurrent overcurrent faults, preventing fault-free outgoing lines from being disconnected, thus minimizing the scope of power loss and reducing the impact of power outages on society.

[0088] In one embodiment, such as Figure 2 , 3 As shown, the power supply and distribution system includes 2 incoming lines, 2 busbar sections, 10 outgoing lines, and 1 bus tie section. Each incoming line is connected to the busbar via an incoming line circuit breaker, and each busbar section is connected to 5 outgoing lines via outgoing line circuit breakers. The two busbar sections are connected by a bus tie section circuit breaker. Each circuit breaker is equipped with a corresponding relay protection device, which controls the closed and open positions of the circuit breaker. For example, the incoming line circuit breaker is equipped with an incoming line relay protection device, the outgoing line circuit breaker is equipped with an outgoing line relay protection device, and the bus tie section circuit breaker is equipped with a bus tie section relay protection device.

[0089] Each relay protection device is equipped with traditional overcurrent protection function. When a single outgoing line overcurrent fault occurs, the traditional outgoing line overcurrent protection takes effect, completing the isolation of the faulty outgoing line. When a single outgoing line overcurrent fault fails to trip, resulting in a bus tie section fault or an incoming line fault, the traditional overcurrent protection of the bus tie section or incoming line takes effect, completing the fault isolation. Among them, the traditional overcurrent protection of outgoing lines, incoming lines, and bus tie sections all include phase overcurrent protection and zero-sequence overcurrent protection. The protection settings of the traditional overcurrent protection are set according to the power supply and distribution system parameters and the upstream and downstream coordination principle.

[0090] like Figure 2 , 3 As shown, when two outgoing lines from the same incoming line experience overcurrent faults simultaneously, or when the bus tie sectionalizing switch is closed, one outgoing line from each of the two incoming lines experiences an overcurrent fault simultaneously. Outgoing lines 1 and 6, which experience overcurrent faults, correspond to incoming lines 1 and 2, respectively. According to the traditional overcurrent protection scheme, if outgoing lines 1 and 6 experience overcurrent faults simultaneously, and the overcurrent protection action time for outgoing lines 1 and 6 is longer than that for incoming lines 1 and 2, then incoming lines 1 and 2 will trip first, causing outgoing lines 2, 3, 4, 5, 7, 8, 9, and 10, which did not experience overcurrent faults, to lose power. Therefore, the traditional overcurrent protection scheme often results in incoming lines tripping before outgoing lines, meaning that traditional relay protection fault isolation methods cannot accurately isolate overcurrent faults, thus increasing the impact of power loss.

[0091] like Figure 1 As shown, the first aspect of the embodiments of this application provides a method for protecting against concurrent faults, including:

[0092] S100, based on the power supply and distribution system parameters and the preset upstream and downstream coordination principle, sets the protection settings for phase overcurrent of outgoing lines and bus tie sections respectively, and sets the protection settings for zero-sequence overcurrent of outgoing lines and bus tie sections respectively.

[0093] In practice, the protection settings include at least one of the following: current setting, delay curve, delay setting, and directional element setting. The specific parameters are set according to the input and output parameters of the power supply and distribution system.

[0094] Substation parameters in a power supply and distribution system include maximum load current capacity, rated phase-to-phase voltage, current transfer ratio, frequency, maximum three-phase fault current of the busbar, and maximum single-phase ground fault current of the busbar. In this embodiment, the concurrent fault protection method is preferably applied to power supply and distribution systems with a voltage level ≤22kV, but it can also be applied to other voltage levels, such as power supply and distribution systems with voltage levels ≤33kV, ≤69kV, ≤138kV, and ≤500kV. Power supply and distribution systems at all voltage levels need to achieve sensitivity and speed in fault isolation so that faults can be promptly isolated and power supply restored as quickly as possible.

[0095] The pre-defined upstream-downstream coordination principle is that the delay setting of the downstream power grid is less than that of the upstream power grid. The delay setting of the downstream power grid is set based on the delay setting of the upstream power grid, so that the delay setting of the upstream power grid is greater than that of the downstream power grid. With this setting, if a fault occurs in the downstream power grid, the fault duration will trigger the delay setting of the downstream power grid first, thus prioritizing the tripping of the downstream power grid and preventing the upstream power grid from tripping first and causing a wider power outage.

[0096] In one embodiment, the substation parameters in the power supply and distribution system are set as follows:

[0097] Maximum load current capacity (MVA): Outgoing line P tr =16, incoming line P tr =50, parent-child joint segment P tr =50;

[0098] Rated phase-to-phase voltage (kV): V t_lv =22;

[0099] Based on the current transformer ratio (CTR) selected by the system: outgoing line CTR = 600 / 1, incoming line CTR = 1800 / 1, bus tie section CTR = 1800 / 1;

[0100] Voltage Transformer Ratio (VTR): VTR = 200 for outgoing lines, incoming lines, and bus tie sections;

[0101] Frequency (Hz): For outgoing lines, incoming lines, and bus tie sections, the frequency is Fr = 50.

[0102] Secondary value of rated voltage (V) for single-phase VT: Vn = 63.5 for outgoing lines, incoming lines, and bus tie sections;

[0103] Maximum 3-phase fault current (A) of 22kV busbar: I for outgoing lines, incoming lines, and bus tie sections. f_3ph =8645;

[0104] Maximum single-phase ground fault current (A) of 22kV busbar: I for outgoing lines, incoming lines, and bus tie sections. f_1ph =9315;

[0105] In practice, in accordance with the State Grid Corporation of China's relay protection technical specifications, current-related protection devices for incoming lines, outgoing lines, and bus tie sections were configured, and the traditional current protection setting methods for each relay protection device were determined based on the aforementioned substation parameters.

[0106] In one embodiment, the power supply and distribution system is configured with the following overcurrent protection parameters:

[0107] S101, the outgoing lines are respectively equipped with two-stage directional phase overcurrent protection 67P and directional zero-sequence overcurrent protection 67G.

[0108] Set the protection settings for directional phase overcurrent of the outgoing line. The protection settings include current setting, delay curve, delay setting, and directional element setting. The specific process is as follows:

[0109] The first section describes the protection settings for transient phase overcurrent, calculated based on the secondary current calculation formula. The secondary current calculation formula is:

[0110]

[0111] Among them, I s For the secondary side current (A), I f_3ph The maximum three-phase fault current (A) is the bus tie section, CTR is the current transformer ratio, and k is the current ratio.

[0112] Calculated based on the maximum three-phase fault current at 100% current ratio, using the secondary side current calculation formula, I s 14.41A: Based on the secondary side current, determine the direction of the instantaneous phase overcurrent setting I for the outgoing line protection. s_ip It is 14.41A.

[0113] The delay setting for the instantaneous phase overcurrent of the outgoing line is set to 0.01s.

[0114] The second section is the protection setting for inverse-time phase overcurrent, calculated based on 120% of the cable current capacity.

[0115] The formula for calculating the primary current is:

[0116]

[0117] Among them, I pri For a single current measurement (A), P tr For maximum load current capacity (MVA), V t_lv Rated phase-to-phase voltage (kV);

[0118] Therefore, the primary side current I pri 419.89A:

[0119] Calculated based on the maximum three-phase fault current at 120% current ratio, and using the above secondary current calculation formula, the secondary current I... s The current setting is 0.84A; based on the secondary side current, the current setting I for the inverse-time direction phase overcurrent of the outgoing line is determined. s_ip It is 0.84A.

[0120] The outgoing line delay is a very inverse time limit. The action delay t during a three-phase fault is obtained based on the very inverse (VI) delay calculation formula.

[0121] The formula for calculating the very inverse time limit is:

[0122]

[0123] Where TMS is the time factor setting, I is the three-phase fault current, Ip is the current setting for omnidirectional phase overcurrent, and t is the protection action delay.

[0124] When the maximum three-phase fault current I is less than 20 times the current setting for phase overcurrent, the operating delay during the maximum three-phase fault of the outgoing line is coordinated with the delay setting for the upstream phase overcurrent of the power supply and distribution system (t = 0.31s). Therefore, the time multiplier TMS for the outgoing line protection operating delay is:

[0125]

[0126] Among them, I f_3ph I is the maximum three-phase fault current of the outgoing line. s_p The outgoing line is set to the directional phase overcurrent, and CTR is the outgoing line current transfer ratio.

[0127] The setpoint for the outgoing line's setting time multiplier is TMS = 0.37;

[0128] At this time, the three-phase fault protection operation time t is... op The calculation formula is obtained based on the protection action time with a TMS of 0.37. The formula is as follows:

[0129]

[0130] In one embodiment, the phase current directional element of the outgoing line satisfies the following: the positive direction is defined as the flow from the busbar to the line, and the outgoing line directional element adopts a 90° connection, i.e., it is set as Ia→Ubc / Ib→Uca / Ic→Uab; the positive direction operation equation is:

[0131]

[0132] in, This refers to the polarization phase current;

[0133] This refers to the polarization phase-to-phase voltage;

[0134] e is the base of the exponential function;

[0135] j is the imaginary unit of the exponential function in the complex plane;

[0136] RCA is the characteristic angle of the device.

[0137] The characteristic angle RCA is preferably 60° to ensure reliable operation in the positive direction and reliable non-operation in the reverse direction.

[0138] The specific setting process for the protection setting value of zero-sequence overcurrent in the outgoing line direction is as follows:

[0139] The first stage is instantaneous zero-sequence overcurrent protection. Referring to the above process, the calculation is based on a 100% single-phase zero-sequence fault circuit:

[0140] The secondary current is:

[0141] Among them, I f_1ph This is the maximum single-phase fault current of the outgoing line.

[0142] The current setpoint for obtaining instantaneous zero-sequence overcurrent is I. s_g =15.53A;

[0143] Set the delay setpoint for the instantaneous zero-sequence overcurrent to t. op =0.01s.

[0144] The second stage is inverse-time directional zero-sequence overcurrent protection, with the zero-sequence starting current calculated based on a 30% proportion of the phase current setting.

[0145] I s =0.3I s_p =0.252A;

[0146] Therefore, the current setting for inverse-time directional zero-sequence overcurrent is I. s_g =0.25A.

[0147] The outgoing line delay is a very inverse time, when the maximum single-phase fault current I f_1ph When the current setting is less than 20 times the zero-sequence overcurrent, and the maximum single-phase current operating delay is coordinated with the zero-sequence current delay (t = 0.1s) of the upstream power grid of the power supply and distribution system, the calculation formula for the time ratio TMS is:

[0148]

[0149] The zero-sequence overcurrent setting time multiple setting value for the outgoing line is obtained as TMS = 0.42.

[0150] The protection action time t for zero-sequence overcurrent in the single-phase overcurrent fault of the outgoing line op The calculation formula is obtained based on the protection action time with a TMS of 0.42. The formula is as follows:

[0151]

[0152] The directional element for zero-sequence overcurrent in the outgoing line satisfies the following: the positive direction is defined as the flow from the busbar to the line, the directional element adopts a 0° connection, i.e., I0-(-U0), and the positive direction operating equation is:

[0153]

[0154] in, The zero-sequence current is polarized;

[0155] The zero-sequence voltage of polarization;

[0156] e is the base of the exponential function;

[0157] j is the imaginary unit of the exponential function in the complex plane;

[0158] RCA is the characteristic angle of the device, and preferably, RCA is set to 240°.

[0159] S102, the bus tie section is configured with one section of non-directional phase overcurrent protection setting 51P and one section of non-directional zero-sequence overcurrent protection 51G.

[0160] The specific setting process for the protection settings of the bus tie section for non-directional phase overcurrent is as follows:

[0161] Configure inverse-time non-directional phase overcurrent protection, and calculate the starting current setting based on 100% of the transformer's rated current:

[0162] The current on one side is:

[0163] The secondary current is:

[0164] The current setting for inverse-time undirected phase overcurrent is then set to I. s_p =0.73A.

[0165] The delay of the bus joint segment action is the standard inverse time, and the standard inverse time is calculated as follows:

[0166]

[0167] Where TMS is the time factor setting, I is the maximum three-phase fault current, Ip is the current setting for omnidirectional phase overcurrent, and t is the protection action delay.

[0168] When the maximum three-phase fault current I is less than 20 times the phase starting current, the operating delay of the bus tie section during the maximum three-phase fault is coordinated with the overcurrent protection delay of the upstream phase of the power supply and distribution system (t = 0.70s), and the setting time ratio of the bus tie section is TMS = 0.19.

[0169] Operating delay t during three-phase fault in bus tie section op The calculation formula is obtained based on the protection action time with a TMS of 0.19. The formula is as follows:

[0170]

[0171] The specific setting process for the protection settings of the bus tie section with omnidirectional zero-sequence overcurrent is as follows:

[0172] Set up inverse-time, non-directional zero-sequence overcurrent protection, with the zero-sequence starting current calculated as 25% of the transformer's rated current.

[0173] Primary current:

[0174] Secondary current:

[0175] The inverse-time undirected zero-sequence overcurrent setting is I. s_g =0.18A.

[0176] The bus tie section omnidirectional zero-sequence overcurrent protection delay is a standard inverse time, when the maximum single-phase fault current I... f_1ph When the starting current of the zero-sequence overcurrent protection is less than 20 times, the maximum single-phase current operation delay of the bus tie section is coordinated with the zero-sequence current delay (t = 0.7s) of the upstream power grid of the power supply and distribution system to obtain the bus tie section zero-sequence overcurrent setting time ratio TMS = 0.35.

[0177] The operating time t of the zero-sequence overcurrent protection for a single-phase overcurrent fault in the bus tie section op The calculation formula is obtained based on the protection action time with a TMS of 0.35. The formula is as follows:

[0178]

[0179] S103, the incoming lines are respectively equipped with a directional phase overcurrent protection 67P and a zero-sequence overcurrent protection 67G.

[0180] The specific process for setting the protection settings for incoming phase overcurrent is as follows:

[0181] Configure inverse-time directional phase overcurrent protection. The starting current setting is calculated based on 125% of the transformer's rated current.

[0182] Primary current:

[0183]

[0184] Secondary current:

[0185]

[0186] The current setting for inverse-time directional phase overcurrent is then obtained as I. s_p =0.91A;

[0187] The incoming line operation delay is a standard inverse time. When the maximum three-phase fault current I is less than 20 times the phase starting current, the operation delay during the maximum three-phase fault of the incoming line is coordinated with the overcurrent protection delay of the upstream phase of the power supply and distribution system (t = 1.12s) to obtain the time multiple setting value of the incoming line TMS = 0.27.

[0188] Action time t during three-phase fault in incoming line op The calculation formula is obtained based on the protection action time with a TMS of 0.27. The formula is as follows:

[0189]

[0190] The wiring method and directional characteristic angle of the directional element are the same as those of the outgoing phase overcurrent protection.

[0191] The specific process for setting the protection settings for zero-sequence overcurrent on the incoming line is as follows:

[0192] Set up inverse-time zero-sequence protection, with the zero-sequence starting current calculated as 30% of the transformer's rated current.

[0193] Primary current:

[0194]

[0195] Secondary current:

[0196]

[0197] The inverse-time directional zero-sequence overcurrent setting is I. s_g =0.22A;

[0198] The incoming line directional zero-sequence overcurrent protection delay is a standard inverse time, when the maximum single-phase fault current I... f_1ph When the starting current of the zero-sequence overcurrent protection is less than 20 times, the maximum single-phase current operating delay of the incoming line is coordinated with the zero-sequence current delay (t = 1.1s) of the upstream of the power grid of the power supply and distribution system to obtain the incoming line zero-sequence overcurrent time ratio setting value TMS = 0.51.

[0199] The operating time t of the zero-sequence overcurrent protection for a single-phase overcurrent fault on the incoming line op The calculation formula is obtained based on the protection action time with a TMS of 0.51. The formula is as follows:

[0200]

[0201] The wiring method and directional characteristic angle of the incoming line directional element are the same as those of the outgoing line zero-sequence overcurrent protection.

[0202] S104, obtain the protection settings for concurrent faults of outgoing lines based on the protection settings for phase overcurrent and zero-sequence overcurrent of outgoing lines, and obtain the protection settings for concurrent faults of bus tie sections based on the protection settings for phase overcurrent and zero-sequence overcurrent of bus tie sections.

[0203] The current setting of the concurrent fault protection of the power supply and distribution system is the same as the current setting of the traditional inverse time overcurrent protection in the above steps. The directional element setting of the concurrent fault protection is the same as the directional element setting of the phase overcurrent and zero sequence overcurrent of the traditional overcurrent protection in the above steps. The concurrent fault protection adopts a time definite time, so the delay curve and delay setting of the concurrent fault are different from those of the traditional overcurrent protection.

[0204] Preferably, the current setting for directional phase overcurrent during concurrent faults of outgoing lines is set to 0.84A, the current setting for directional zero-sequence overcurrent is set to 0.25A, and the action delay setting is set to 0.1s; the current setting for non-directional phase overcurrent during concurrent faults of bus tie sections is set to 0.73A, the current setting for non-directional zero-sequence overcurrent is set to 0.18A, and the action delay setting is set to 0.1s. The directional element setting for concurrent fault protection of outgoing lines is the same as the directional element setting for phase overcurrent and zero-sequence overcurrent of traditional overcurrent protection in the above steps.

[0205] S200, the relay protection devices of each incoming line are set to the concurrent fault protection enabled state.

[0206] In practice, all relay protection devices are equipped with concurrent fault protection functions. When two or more outgoing lines experience overcurrent faults simultaneously, the concurrent fault protection function is activated to disconnect the outgoing lines experiencing concurrent fault overcurrent. Concurrent fault protection is a comprehensive and coordinated protection function that comprehensively assesses the overcurrent fault conditions of all incoming lines, outgoing lines, and sections in the entire power supply and distribution system. Concurrent fault protection is independent of the overcurrent protection function of traditional protection and is an improvement on the existing traditional overcurrent protection function.

[0207] The relay protection devices of each incoming line are set to concurrent fault protection enabled, so that concurrent fault protection can confirm the fault status of the corresponding outgoing line and thus accurately disconnect the outgoing line with a concurrent fault. Concurrent fault protection enabling includes hard-panel enabling, soft-panel enabling, and control word enabling. The concurrent fault enabling logic is as follows: Figure 4 As shown, concurrent faults are detected by the input line 1 or 2. The concurrent fault protection of input line 1 or 2 is activated when all three activation conditions are 1.

[0208] Concurrent fault protection for each incoming and downstream outgoing line can be independently enabled or disabled. When enabled, concurrent fault protection for this incoming and downstream outgoing lines is effective; when disabled, concurrent fault protection for this incoming and downstream outgoing lines is ineffective, but traditional overcurrent protection remains effective. For example, in... Figure 3 In the event of a simultaneous overcurrent fault on outgoing lines 1, 2, 6, and 7, if the concurrent fault protection for incoming lines 1 and 2 is activated and the bus tie sectionalizing circuit breaker is in the closed position, then the concurrent fault protection for all four outgoing lines will be activated simultaneously (e.g., outgoing lines 1, 2, 6, and 7). If the concurrent fault protection for incoming lines 1 and 2 is activated, but the bus tie sectionalizing circuit breaker is in the open position, then the concurrent fault protection for two outgoing lines will be activated simultaneously (e.g., outgoing lines 1 and 2 corresponding to incoming line 1, and outgoing lines 6 and 7 corresponding to incoming line 2). If the concurrent fault protection for incoming line 1 is activated, but the concurrent fault protection for incoming line 2 is deactivated, then only outgoing lines 1 and 2 will have their concurrent fault protection activated; the concurrent fault protection for outgoing lines 6 and 7 will be ineffective.

[0209] In one embodiment, based on the incoming line concurrent fault activation type, the protection setting parameters for some concurrent faults in the power supply and distribution system are shown in Table 1 below:

[0210]

[0211] Table 1

[0212] The directional element for concurrent fault protection of outgoing lines is the same as the directional element for phase overcurrent and zero-sequence overcurrent protection in the aforementioned steps.

[0213] S300, the outgoing line relay protection device collects the current flowing through multiple outgoing lines respectively.

[0214] The power supply and distribution system in this embodiment includes 10 outgoing lines, 2 incoming lines, 2 busbar sections, and 1 bus tie section. After setting the incoming line relay protection device to the concurrent fault protection activation state and setting the protection settings for concurrent faults of the outgoing lines and the bus tie section, the 10 outgoing line relay protection devices simultaneously collect the current flowing through the corresponding outgoing line.

[0215] S400: When multiple outgoing line relay protection devices simultaneously detect that the current and direction elements of several outgoing lines meet preset conditions, the outgoing line relay protection devices determine that several outgoing lines are concurrent fault outgoing lines and obtain the concurrent fault status of each concurrent fault outgoing line.

[0216] In specific implementation, such as Figure 5 As shown, if the current flowing through any outgoing line is greater than or equal to the outgoing line's current setting, the traditional overcurrent protection of that outgoing line will be triggered. For example... Figure 6 , 7 As shown, when multiple outgoing line relay protection devices simultaneously detect that the current and direction elements of at least two outgoing lines meet preset conditions, the outgoing line relay protection devices determine that these two outgoing lines are concurrent fault outgoing lines and obtain the concurrent fault status of these two concurrent fault outgoing lines.

[0217] The preset conditions include a first preset condition, which is:

[0218] The current of several outgoing lines is greater than or equal to the preset phase overcurrent setting value of the outgoing lines.

[0219] And the directional elements meet the requirements.

[0220] The requirements for the directional element in the first preset condition are the same as the requirements for the directional element of the phase current flow in the outgoing line in S101 above.

[0221] For example, such as Figure 6 As shown, if the phase currents flowing through outgoing lines 1 and 2 are both greater than or equal to the preset phase overcurrent setting value I of the outgoing lines, s_p If the directional element meets the above requirements, then the concurrent fault overcurrent protection of outgoing lines 1 and 2 is triggered, thereby obtaining concurrent fault outgoing lines 1 and 2.

[0222] For example, such as Figure 7 As shown, if the phase currents flowing through outgoing lines 1 and 6 are both greater than or equal to the preset phase overcurrent setting value I of the outgoing lines, s_p If the directional element meets the above requirements, then the concurrent fault overcurrent protection of outgoing lines 1 and 6 is triggered, thereby obtaining concurrent fault outgoing lines 1 and 6.

[0223] The preset conditions also include a second preset condition, which is:

[0224] The current of several outgoing lines is greater than or equal to the preset zero-sequence overcurrent current setting value for the outgoing line direction;

[0225] And the directional elements meet the requirements.

[0226] The requirements for the directional element in the second preset condition are the same as those for the zero-sequence overcurrent directional element in S101 above.

[0227] For example, if the zero-sequence current flowing through outgoing lines 1 and 2 of the power supply and distribution system is greater than or equal to the preset zero-sequence overcurrent setting I for the outgoing lines. s_g If the directional element setting meets the above requirements, then the concurrent fault overcurrent protection of outgoing lines 1 and 2 is triggered, thereby obtaining concurrent fault outgoing lines 1 and 2.

[0228] For example, if the zero-sequence current flowing through outgoing lines 1 and 6 of the power supply and distribution system is greater than or equal to the preset zero-sequence overcurrent setting I for the outgoing lines... s_g If the directional element setting meets the above requirements, then the concurrent fault overcurrent protection of outgoing lines 1 and 6 is triggered, thereby obtaining concurrent fault outgoing lines 1 and 6.

[0229] The concurrent fault states include the first concurrent fault state, which includes:

[0230] The bus tie sectionalizing circuit breaker is in the open position;

[0231] Each concurrent fault outgoing line is connected to the same concurrent fault bus.

[0232] For example, the outgoing line relay protection device acquires the concurrent fault status of outgoing lines 1 and 2.

[0233] First, the outgoing line relay protection device obtains the open / closed status of the bus tie section circuit breaker from the bus tie section relay protection device.

[0234] If the bus tie section circuit breaker is in the open position, then determine the fault status of the downstream outgoing lines of bus 1 and bus 2 respectively. Since outgoing lines 1 and 2 are both connected to bus 1 and are both concurrent fault outgoing lines, the outgoing line relay protection device obtains the concurrent fault status of concurrent fault outgoing lines 1 and 2 as the first concurrent fault status.

[0235] The concurrent fault state also includes the concurrent fault second state, which includes:

[0236] The bus tie section circuit breaker is in the closed position;

[0237] Each concurrent fault outgoing line is connected to at least two concurrent fault bus sections;

[0238] The bus tie section relay protection device determines that the current flowing through the bus tie section between each concurrent fault bus is greater than or equal to the preset phase overcurrent current setting of the bus tie section, or determines that the current flowing through the bus tie section between each concurrent fault bus is greater than or equal to the preset zero-sequence overcurrent current setting of the bus tie section.

[0239] For example, the outgoing line relay protection device acquires the concurrent fault status of outgoing lines 1 and 6.

[0240] First, the outgoing line relay protection device obtains the open / closed status of the bus tie section circuit breaker from the bus tie section relay protection device.

[0241] If the bus tie section circuit breaker is in the closed position, then the concurrent fault status of all outgoing lines downstream of bus 1 and bus 2 is determined by detection.

[0242] If concurrent fault outgoing lines 1 and 6 are connected to at least two concurrent fault busbars, for example, concurrent fault outgoing line 1 is connected to concurrent fault busbar 1 and concurrent fault outgoing line 6 is connected to concurrent fault busbar 2.

[0243] For example, such as Figure 8 As shown, if the bus tie section relay protection device determines that the phase current flowing through the bus tie section between the concurrent fault busbars 1 and 2 is greater than or equal to the preset phase overcurrent setting of 0.73A for the bus tie section, or determines that the zero-sequence current flowing through the bus tie section between the concurrent fault busbars 1 and 2 is greater than or equal to the preset zero-sequence overcurrent setting of 0.18A for the bus tie section, then the bus tie section relay protection device will activate overcurrent protection. If there is a concurrent fault outgoing line, then the bus tie section relay protection device will activate the concurrent fault protection function.

[0244] The outgoing line relay protection device obtains the concurrent fault status of outgoing lines 1 and 6 as the second concurrent fault status.

[0245] It should be noted that for two adjacent busbars with corresponding two incoming lines, such as incoming line 1 and incoming line 2, if the concurrent fault incoming line 1 is in the concurrent fault enabled state but the concurrent fault incoming line 2 is in the concurrent fault disabled state, then only the concurrent fault status of outgoing lines 1 to 5 downstream of the concurrent fault incoming line 1 will be obtained. The concurrent fault protection of outgoing lines 6 to 10 downstream of the concurrent fault incoming line 2 will be disabled, and the concurrent fault status of outgoing lines 6 to 10 downstream of the concurrent fault incoming line 2 will not be obtained, but the traditional overcurrent protection will still be effective. Similarly, the above situation also applies when the concurrent fault incoming line 2 is in the concurrent fault enabled state but the concurrent fault incoming line 1 is in the concurrent fault disabled state.

[0246] In addition, for two adjacent busbars corresponding to two incoming lines, such as incoming line 1 and incoming line 2, if both incoming line 1 and incoming line 2 are in the concurrent fault enabled state and the bus tie section circuit breaker is in the closed state, then all outgoing lines downstream of the two incoming lines will participate in the concurrent fault judgment at the same time. As long as there is a concurrent fault outgoing line, the concurrent fault status of the concurrent fault outgoing line will be obtained.

[0247] S500, based on concurrent fault status, fault duration and preset concurrent fault delay setting, the outgoing line relay protection device uses concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip, so as to isolate each concurrent fault outgoing line.

[0248] If the concurrent fault status of each concurrent fault outgoing line meets the first concurrent fault status or the second concurrent fault status, the outgoing line relay protection device will time the duration of the fault of each concurrent fault outgoing line.

[0249] For example, if concurrent fault outgoing lines 1 and 2 meet the first state of concurrent fault, then the outgoing line relay protection devices will time the fault duration of concurrent fault outgoing lines 1 and 2 respectively.

[0250] For example, if concurrent fault outgoing lines 1 and 6 meet the second state of concurrent fault, then the outgoing line relay protection devices will time the fault duration of concurrent fault outgoing lines 1 and 6 respectively.

[0251] Among them, the concurrent fault logic judgment method includes the distributed concurrent fault logic judgment method, which includes:

[0252] S510, each outgoing line relay protection device receives the concurrent fault protection activation / deactivation signal sent by each incoming line relay protection device;

[0253] S511, if the concurrent fault protection enable / disable signal is the concurrent fault protection enabled state, the outgoing line relay protection devices corresponding to each concurrent fault outgoing line shall time the fault duration of the concurrent fault outgoing line respectively.

[0254] S512 If the fault duration of a concurrent fault outgoing line is greater than or equal to the preset concurrent fault delay setting, the outgoing line relay protection device of each concurrent fault outgoing line outputs an output signal to the corresponding connected outgoing line circuit breaker to trip.

[0255] In one embodiment, preferably, the preset concurrent fault delay setting is 0.1s.

[0256] For example, the process by which the outgoing line relay protection device uses a distributed concurrent fault logic judgment method to control the outgoing line circuit breakers corresponding to concurrent fault outgoing lines 1 and 2 to trip is as follows:

[0257] The outgoing line relay protection devices of outgoing lines 1 and 2 respectively receive the concurrent fault protection activation / deactivation signals sent by the incoming line relay protection device of incoming line 1.

[0258] If the concurrent fault protection enable / disable signal indicates that the concurrent fault protection is enabled, the relay protection devices corresponding to the concurrent fault outgoing lines 1 and 2 will time the duration of the concurrent fault outgoing lines 1 and 2 respectively.

[0259] If the fault duration of concurrent fault outgoing lines 1 and 2 is greater than or equal to 0.1s, the outgoing line relay protection devices of concurrent fault outgoing lines 1 and 2 will output an output signal to the corresponding connected outgoing line circuit breaker to trip.

[0260] After tripping the concurrent faulty outgoing lines 1 and 2, the concurrent faulty outgoing lines 1 and 2 are isolated, while the outgoing lines 3, 4, and 5 without faults continue to be powered, thus achieving precise and rapid isolation of concurrent overcurrent faulty outgoing lines.

[0261] For example, the outgoing line relay protection devices of outgoing lines 1 and 6 receive concurrent fault protection activation / deactivation signals sent by the incoming line relay protection devices of incoming lines 1 and 2, respectively.

[0262] If the concurrent fault protection activation / deactivation signals of incoming lines 1 and 2 are both in the concurrent fault protection activation state, the outgoing line relay protection devices corresponding to concurrent fault outgoing lines 1 and 6 will time the fault duration of concurrent fault outgoing lines 1 and 6 respectively.

[0263] If the fault duration of concurrent fault outgoing lines 1 and 6 is greater than or equal to 0.1s, the outgoing line relay protection devices of concurrent fault outgoing lines 1 and 6 will output an output signal to the corresponding connected outgoing line circuit breaker to trip.

[0264] After tripping the concurrent faulty outgoing lines 1 and 6, the concurrent faulty outgoing lines 1 and 6 are isolated, allowing the non-faulty outgoing lines 2, 3, 4, 5 or outgoing lines 7, 8, 9, 10 to continue to be powered, thus achieving precise and rapid isolation of concurrent overcurrent faulty outgoing lines.

[0265] Concurrent fault logic judgment methods include centralized concurrent fault logic judgment methods;

[0266] Centralized concurrent fault logic judgment methods include:

[0267] S520, the bus tie section relay protection device receives concurrent fault protection activation / deactivation signals sent by the corresponding connected incoming line relay protection devices;

[0268] S521, if the concurrent fault protection enable / disable signal is the concurrent fault protection enabled state, the bus tie section relay protection device times the fault duration of each concurrent fault outgoing line.

[0269] S522, if the fault duration of the concurrent fault outgoing line is greater than or equal to the preset concurrent fault delay setting, the bus tie section relay protection device sends a trip signal to the outgoing line relay protection device corresponding to each concurrent fault outgoing line.

[0270] S523, the outgoing line relay protection device of each concurrent fault outgoing line receives the trip signal and outputs an output signal to the corresponding connected outgoing line circuit breaker to trip.

[0271] For example, the process by which the outgoing line relay protection device uses a centralized concurrent fault logic judgment method to control the outgoing line circuit breakers corresponding to concurrent fault outgoing lines 1 and 2 to trip is as follows:

[0272] The bus tie section relay protection devices receive concurrent fault protection activation / deactivation signals sent by the incoming line relay protection device of incoming line 1.

[0273] If the concurrent fault protection signal of incoming line 1 is in the concurrent fault protection enabled state, the bus tie section relay protection device will time the fault duration of concurrent fault outgoing lines 1 and 2 respectively.

[0274] If the duration of the concurrent fault outgoing lines 1 and 2 is greater than or equal to 0.1s, the bus tie sectional relay protection device sends a trip signal to the outgoing line relay protection device corresponding to the concurrent fault outgoing lines 1 and 2.

[0275] The outgoing line relay protection devices of concurrent fault outgoing lines 1 and 2 receive the trip signal and output the output signal to the corresponding connected outgoing line circuit breaker to trip.

[0276] After tripping the concurrent faulty outgoing lines 1 and 2, the concurrent faulty outgoing lines 1 and 2 are isolated, while the outgoing lines 3, 4, and 5 without faults continue to be powered, thus achieving precise and rapid isolation of concurrent overcurrent faulty outgoing lines.

[0277] For example, the process by which the outgoing line relay protection device uses a centralized concurrent fault logic judgment method to control the outgoing line circuit breakers corresponding to concurrent fault outgoing lines 1 and 6 to trip is as follows:

[0278] The bus tie section relay protection device receives concurrent fault protection activation / deactivation signals from the incoming line relay protection devices of incoming lines 1 and 2, respectively.

[0279] If the concurrent fault protection activation / deactivation signals for incoming lines 1 and 2 are both in the concurrent fault protection activation state, the bus tie sectional relay protection device will time the fault duration of concurrent fault outgoing lines 1 and 6 respectively.

[0280] If the fault duration of concurrent fault outgoing lines 1 and 6 is greater than or equal to 0.1s, the bus tie sectional relay protection device sends a trip signal to the outgoing line relay protection device corresponding to concurrent fault outgoing lines 1 and 6.

[0281] The outgoing relay protection devices of concurrent fault outgoing lines 1 and 6 receive the trip signal and output the output signal to the outgoing circuit breaker connected to the corresponding outgoing lines 1 and 6 to trip.

[0282] After tripping the concurrent faulty outgoing lines 1 and 6, the concurrent faulty outgoing lines 1 and 6 are isolated, allowing the non-faulty outgoing lines 2, 3, 4, 5 or outgoing lines 7, 8, 9, 10 to continue to be powered, thus achieving precise and rapid isolation of concurrent overcurrent faulty outgoing lines.

[0283] In the specific logic implementation, all overcurrent start signals from downstream of incoming line 1 / busbar 1 can be aggregated, and the overcurrent start signals from incoming line 2 / busbar 2 and the overcurrent start signals from the bus tie section can be aggregated for concurrent fault protection logic judgment. For example... Figure 9 , Figure 10 The diagram shows the tripping logic when the concurrent fault conditions of outgoing line 1 are met. It also applies to any other outgoing line.

[0284] like Figure 6 As shown, the relay protection devices of incoming line 1 and incoming line 2 are both set to the concurrent fault protection enabled state; when the current flowing through outgoing lines 1 and 2 collected by the outgoing line relay protection device is greater than or equal to the current setting value of the outgoing line, and the setting value of the directional element meets the preset condition, the concurrent fault overcurrent protection of outgoing lines 1 and 2 is triggered; after the concurrent fault overcurrent protection of outgoing lines 1 and 2 is activated, the outgoing line relay protection device determines that the overcurrent outgoing lines 1 and 2 are concurrent fault outgoing lines 1 and 2, and obtains the concurrent fault status of concurrent fault outgoing lines 1 and 2; Since the concurrent fault states of concurrent fault outgoing lines 1 and 2 correspond to the same concurrent fault bus 1, and the bus tie sectionalizing circuit breaker is in the open position, the concurrent fault states of concurrent fault outgoing lines 1 and 2 are the first concurrent fault state. The fault duration of concurrent fault outgoing lines 1 and 2 is timed. If the fault duration of concurrent fault outgoing lines 1 and 2 is greater than or equal to the preset concurrent fault setting delay of 0.1s, the outgoing circuit breaker corresponding to concurrent fault outgoing lines 1 and 2 is tripped to isolate each concurrent fault outgoing line 1 and 2.

[0285] like Figure 7 As shown, the relay protection devices of incoming lines 1 and 2 are both set to concurrent fault protection enabled. When the current flowing through outgoing lines 1 and 6 collected by the outgoing line relay protection device is greater than or equal to the current setting of the outgoing lines, and the setting of the directional element meets the preset conditions, the concurrent fault overcurrent protection of outgoing lines 1 and 6 is triggered. After the concurrent fault overcurrent protection of outgoing lines 1 and 6 is activated, the outgoing line relay protection device determines that the overcurrent outgoing lines 1 and 6 are concurrent fault outgoing lines 1 and 6, and obtains the concurrent fault status of concurrent fault outgoing lines 1 and 6. Since the bus tie section between busbars 1 and 2 where concurrent fault outgoing lines 1 and 6 are located is in the closed position... If the concurrent fault outgoing line 1 corresponds to the concurrent fault bus 1 and the concurrent fault outgoing line 6 corresponds to the concurrent fault bus 2, and the current flowing through the bus tie section between the concurrent fault buses 1 and 2 is greater than or equal to the current setting value of the bus tie section, and the concurrent fault state of the concurrent fault outgoing lines 1 and 2 is the second concurrent fault state, then the fault duration of the concurrent fault outgoing lines 1 and 6 is timed. If the fault duration of the concurrent fault outgoing lines 1 and 6 is greater than or equal to the preset concurrent fault setting delay of 0.1s, the outgoing circuit breaker corresponding to the concurrent fault outgoing lines 1 and 6 is controlled to trip, so as to isolate each concurrent fault outgoing line 1 and 6.

[0286] In one embodiment, a comparative verification of traditional overcurrent protection and concurrent fault overcurrent protection is performed. When multiple (2 to 10) outgoing lines fail simultaneously, and the fault points of each outgoing line are the same, the fault current of the incoming line is the sum of the faults of all outgoing lines. The operating times of traditional overcurrent protection and concurrent fault protection are shown in Table 2.

[0287]

[0288] Table 2

[0289] Among them, the operating time t1 of the outgoing line overcurrent is calculated according to the following calculation formula:

[0290]

[0291] For the incoming line, when overcurrent faults occur simultaneously in X outgoing lines, the fault current of the incoming line is X times the fault current of the outgoing line, where X = 2 to 10. The operating time t2 of the incoming line for concurrent faults of the traditional overcurrent protection is calculated according to the following calculation formula:

[0292]

[0293] As can be seen from the table, among the 36 data corresponding to 4 verified fault currents (the fault current of the outgoing line is less than the current setting value of the instantaneous overcurrent (i.e., I < Is_ip)), if the traditional overcurrent protection is put into operation but the concurrent fault protection is not put into operation, and the operating delay time is calculated through the inverse time curve for the traditional overcurrent protection of the incoming line and the outgoing line, then for 30 data, the operating time of the incoming line is less than that of the outgoing line, and the incoming line will trip first; if the traditional overcurrent protection and the concurrent fault protection are put into operation simultaneously, since the delay setting value of the concurrent fault is 0.1 s, which is less than the delay calculated by the inverse time curve of all traditional overcurrent protections, the outgoing line with the concurrent fault will trip first; when the fault currents of multiple outgoing lines are greater than or equal to the current setting value of the instantaneous overcurrent (i.e., I ≥ Is_ip), the instantaneous overcurrent protection of the outgoing line will be started simultaneously, and the traditional delay time is the same as the concurrent fault delay time, and the action results are the same. Therefore, for all concurrent faults of multiple outgoing lines in the table, through the concurrent fault protection method of this embodiment, it can be ensured that the outgoing line with the concurrent fault trips first to isolate each outgoing line with the concurrent fault, avoiding the risk that the incoming line trips first due to the operating time of the incoming line for concurrent faults being less than the operating time of the outgoing line overcurrent. The outgoing lines without overcurrent faults will continue to be powered, achieving accurate and rapid isolation of the outgoing lines with concurrent faults and reducing the power outage range.

[0294] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution is prior or subsequent. The order of execution of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0295] As Figure 11 shown, in the distributed concurrent fault logic judgment method corresponding to Figure 2In the concurrent fault protection power distribution system, the concurrent fault module in the relay protection device of each outgoing line receives 9 overcurrent start signals from the other 9 outgoing line concurrent fault modules. The outgoing line relay protection device controls the corresponding outgoing line circuit breaker to trip. At the same time, it receives 2 signals for the activation / deactivation status of the concurrent fault modules of the 2 incoming lines, and 1 signal for the overcurrent start information of the bus tie section, for a total of 12 signals. The 10 outgoing line concurrent fault modules will have a total of 120 signals, that is, the total number of signals is 12*N (N is the number of outgoing lines).

[0296] If using GOOSE (Generic Object Oriented Substation Event) wiring to configure a distributed concurrent fault module, 120 signals need to be connected in the SCD (Substation Configuration Description) configuration. If a concurrent fault module is added, the goose information of all outgoing lines needs to be reconfigured (i.e., 12 goose connections need to be added for each additional outgoing line). If using hardware wiring, for each additional concurrent fault module, one optocoupler input terminal needs to be added to all outgoing lines for receiving information.

[0297] In the distributed concurrent fault judgment method, the corresponding example is... Figure 2 The terminal connections corresponding to the concurrent fault protection power supply and distribution system are shown in Table 3, where "√" indicates that there is a corresponding connection:

[0298]

[0299] Table 3

[0300] like Figure 12 As shown, in the centralized concurrent fault logic judgment method, the corresponding method is as follows: Figure 2 In the concurrent fault protection power distribution system, the bus tie section relay protection device uniformly receives the overcurrent start signal from the concurrent fault modules of all 10 outgoing lines, totaling 10 signals; the bus tie section relay protection device also sends trip signals to the outgoing line relay protection devices corresponding to each concurrent fault outgoing line, totaling 10 signals, and the outgoing line relay protection devices control the corresponding outgoing line circuit breakers to trip; the bus tie section relay protection device also simultaneously receives the concurrent fault enable / disable status signals of 2 incoming line concurrent fault modules, totaling 22 signals, i.e., 2×N+M (N is the number of outgoing lines, and M is the number of incoming lines).

[0301] If GOOSE wiring is used, adding a concurrent fault module requires reconfiguring the GOOSE information of the bus tie section (i.e., for each additional outgoing line, two additional GOOSE connections are required), while other devices do not need to be changed.

[0302] If the hardware line method is used, the bus tie segment concurrent fault module needs to add two optocoupler input terminals for receiving information.

[0303] In the centralized concurrent fault logic judgment method, the corresponding example is... Figure 2 The terminal connections corresponding to the concurrent fault protection power supply and distribution system shown are represented in a table, as shown in Table 4. "√" indicates that there is a corresponding connection:

[0304]

[0305]

[0306] Table 4

[0307] Table 5 shows the differences between centralized and distributed solutions for concurrent fault power distribution systems. The distributed solution has more signal connections, allowing the SF6 (Signal Transfer Function) of other relays to continue functioning even when one relay fails or is under maintenance. In contrast, the centralized solution has fewer signal connections, and the SF6 function fails when a bus tie sectional relay fails. Therefore, the recommended approach is: a centralized solution is suitable for projects using traditional relays; a distributed solution is suitable for digital relays supporting GOOSE signal transmission.

[0308]

[0309] Table 5

[0310] The second aspect of this application provides a relay protection device for concurrent faults, including: an analog quantity acquisition module, an input quantity acquisition module, an output quantity module, a memory, a processor, and a computer program stored in the memory and executable on the processor.

[0311] The analog signal acquisition module is used to acquire analog signals and output them to the processor;

[0312] Input signal acquisition module is used to acquire input signals from the power supply and distribution system and transmit them to the processor;

[0313] The output module is used to send the output signal from the processor;

[0314] When a processor executes a computer program, it implements the steps of the method as described in any of the first aspects.

[0315] The relay protection device for concurrent faults also includes a display device for displaying and refreshing various data of the relay protection for concurrent faults.

[0316] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0317] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for protecting against concurrent faults, applied to a power supply and distribution system, wherein the power supply and distribution system includes M incoming lines, M bus sections, N outgoing lines, and M-1 bus tie sections, wherein, M1, N2, N>M; Each incoming line is connected to the busbar via an incoming line circuit breaker, each section of the busbar is connected to the corresponding multiple outgoing lines via an outgoing line circuit breaker, and two sections of the busbar are connected by a bus tie sectionalizing circuit breaker. The incoming circuit breaker is equipped with an incoming line relay protection device, the outgoing circuit breaker is equipped with an outgoing line relay protection device, and the bus tie sectional circuit breaker is equipped with a bus tie sectional relay protection device. The concurrent fault protection method is characterized by comprising: The incoming line relay protection device is set to the concurrent fault protection enabled state; The outgoing line relay protection device collects the current flowing through multiple outgoing lines respectively; When multiple outgoing line relay protection devices simultaneously detect that the current and direction elements of several outgoing lines meet preset conditions, the outgoing line relay protection devices determine that several outgoing lines are concurrent fault outgoing lines and obtain the concurrent fault status of each concurrent fault outgoing line. Based on the concurrent fault status, fault duration, and preset concurrent fault delay setting, the outgoing line relay protection device uses a concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip, so as to isolate each concurrent fault outgoing line. Based on the concurrent fault state, the fault duration, and a preset concurrent fault delay setting, the outgoing line relay protection device uses a concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip, including: Based on the concurrent fault state, the fault duration, and the preset concurrent fault delay setting, the outgoing line relay protection device uses a distributed concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip. The distributed concurrent fault logic judgment method includes: Each of the outgoing line relay protection devices receives the concurrent fault protection activation / deactivation signal sent by each of the incoming line relay protection devices; If the concurrent fault protection enable / disable signal is in the concurrent fault protection enable state, and based on the concurrent fault state, the outgoing line relay protection device corresponding to each concurrent fault outgoing line respectively times the fault duration of the concurrent fault outgoing line; If the duration of the concurrent fault outgoing line is greater than or equal to the preset concurrent fault delay setting, the outgoing line relay protection device of each concurrent fault outgoing line outputs an output signal to the corresponding connected outgoing line circuit breaker to trip.

2. The protection method as described in claim 1, characterized in that, Before the step of setting the relay protection device of each of the incoming lines to the concurrent fault protection enabled state, the method further includes: Based on the power supply and distribution system parameters and the preset upstream and downstream coordination principle, the protection settings for phase overcurrent of the outgoing line and the bus tie section are set respectively, and the protection settings for zero-sequence overcurrent of the outgoing line and the bus tie section are set respectively.

3. The protection method as described in claim 2, characterized in that, The protection settings include at least one of the following: current setting, delay curve, delay setting, and direction element setting.

4. The protection method as described in claim 3, characterized in that, The preset conditions include a first preset condition; The preset first condition is: The current of each of the several outgoing lines is greater than or equal to the preset phase overcurrent current setting of the outgoing line; Furthermore, the directional element is defined as flowing from the busbar to the line in the positive direction. The directional element adopts a 90° connection, i.e., Ia→Ubc / Ib→Uca / Ic→Uab. The positive direction operation equation is: in, This refers to the polarization phase current; This refers to the polarization phase-to-phase voltage; e is the base of the exponential function; j is the imaginary unit of the exponential function in the complex plane; RCA is the characteristic angle of the device.

5. The protection method as described in claim 3, characterized in that, The preset conditions also include a preset second condition; The preset second condition is: The current of each of the several outgoing lines is greater than or equal to the preset zero-sequence overcurrent current value of the outgoing line. Furthermore, the directional element is defined as flowing from the busbar to the line in the positive direction. The directional element adopts a 0° connection, i.e., I0-(-U0), and the positive direction operation equation is: in, The zero-sequence current is polarized; The zero-sequence voltage of polarization; e is the base of the exponential function; j is the imaginary unit of the exponential function in the complex plane; RCA is the characteristic angle of the device.

6. The protection method as described in claim 1, characterized in that, The concurrent fault state includes the concurrent fault first state; The first state of concurrent failure includes: The bus tie section circuit breaker is in the open position; All of the concurrent fault outgoing lines are connected to the same concurrent fault bus.

7. The protection method as described in claim 1, characterized in that, The concurrent fault state also includes a concurrent fault second state; The second concurrent failure state includes: The bus tie section circuit breaker is in the closed position; Each of the aforementioned concurrent fault outgoing lines is connected to at least two concurrent fault busbars; The bus tie section relay protection device determines that the current flowing through the bus tie section between each of the concurrent fault buses is greater than or equal to the preset phase overcurrent current setting of the bus tie section, or determines that the current flowing through the bus tie section between each of the concurrent fault buses is greater than or equal to the preset zero-sequence overcurrent current setting of the bus tie section.

8. The protection method as described in claim 1, characterized in that, Based on the concurrent fault state, the fault duration, and a preset concurrent fault delay setting, the outgoing line relay protection device uses a concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip, further comprising: Based on the concurrent fault status, the fault duration, and the preset concurrent fault delay setting, the outgoing line relay protection device uses a centralized concurrent fault logic judgment method to control the outgoing line circuit breaker corresponding to each concurrent fault outgoing line to trip. The centralized concurrent fault logic judgment method includes: The bus tie section relay protection device receives concurrent fault protection activation / deactivation signals sent by each of the corresponding connected incoming line relay protection devices; If the concurrent fault protection enable / disable signal indicates that the concurrent fault protection is enabled, and based on the concurrent fault status, the bus tie section relay protection device counts the duration of the fault for each of the concurrent fault outgoing lines. If the duration of the concurrent fault outgoing line is greater than or equal to the preset concurrent fault delay setting, the bus tie section relay protection device sends a trip signal to the outgoing line relay protection device corresponding to each concurrent fault outgoing line. Each of the outgoing line relay protection devices that cause concurrent faults receives the trip signal and outputs an output signal to the corresponding connected outgoing line circuit breaker to trip the circuit breaker.

9. A relay protection device for concurrent faults, applied in a power supply and distribution system, comprising: Analog signal acquisition module, input signal acquisition module, output signal module, memory, processor, and computer program stored in the memory and executable on the processor; The analog quantity acquisition module is used to acquire analog quantities of the power supply and distribution system and output them to the processor; The input signal acquisition module is used to acquire the input signal of the power supply and distribution system and transmit it to the processor; The output module is used to send the output signal from the processor; The characteristic is that, when the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 8.

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