A power distribution network hybrid grounding system and a closing loop and switching operation control method
Patent Information
- Application Number
- CN202311460738.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-03
- Publication Date
- 2026-10-23
- Estimated Expiration
- 2043-11-03
AI Technical Summary
不同接地方式系统负荷倒切时两种接地方式并存，且倒切后原有系统负荷增加，若在此过程中发生单相接地故障，将会出现NRS继电保护误动与系统故障电流增加，导致停电范围扩大或消弧线圈不能有效补偿等问题
[0005]本发明的目的是针对现有技术的不足，从而提供一种配电网混合接地系统及合环倒切操作控制方法。
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Figure CN117543547B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a loop-closing and reverse-switching operation control, specifically, to a hybrid grounding system for a power distribution network and a loop-closing and reverse-switching operation control method. Background Technology
[0002] Urban power distribution networks are hybrid grounding systems comprising Neutral Resistance Grounding System (NRS) and Neutral Resonant Grounding System (NES). During faults and maintenance, load shedding between these different grounding systems is inevitable. When load shedding occurs, both grounding methods coexist, and the load on the original system increases after the shedding. If a single-phase ground fault occurs during this process, it can lead to NRS relay protection malfunctions and increased system fault current, resulting in problems such as expanded power outage areas or ineffective compensation by the arc suppression coil.
[0003] Regarding the fault scenarios of mixed operation of NRS and NES during the loop-closing and switching process, and the fault scenarios of multiple loads in a separate grounding system, some experts have analyzed the impact of single-phase grounding faults on the zero-sequence protection of the system, taking the loop closure of a substation with low resistance grounding and a substation with arc suppression coil grounding as the background. However, they have not analyzed the faults occurring on the low resistance grounding side. Some experts have also studied the impact of single-phase grounding faults through fixed resistance in a mixed grounding system with loop closure at the end of the feeder on the zero-sequence current protection of the low resistance grounding side. However, their fault types do not consider the nonlinear grounding arc phenomenon that often accompanies single-phase grounding faults, nor do they consider the case where the loop closure point is located on the busbar.
[0004] In order to solve the above problems, people have been seeking an ideal technological solution. Summary of the Invention
[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a hybrid grounding system for power distribution networks and a loop-closing and switching operation control method.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A hybrid grounding system for a power distribution network includes a low-resistance grounding system on the left, an arc-suppression coil grounding system on the right, and a loop connection line for connecting the low-resistance grounding system and the arc-suppression coil grounding system.
[0008] The loop connection point between the loop connection line and the small resistance grounding system is located at the beginning of feeder 1, so that the reverse-cut line and the feeder of the small resistance grounding system share a set of zero-sequence current protection.
[0009] Zero-sequence current protection is installed on the side of the closed-loop interconnection line closest to the arc suppression coil grounding system. The side of the closed-loop interconnection line closest to the low-resistance grounding system shares a set of zero-sequence current protection with the feeder of the low-resistance grounding system.
[0010] When a single-phase ground fault occurs on the low-resistance side of a hybrid grounding system, the zero-sequence current protection originally installed on the NRS side remains effective, enabling rapid and accurate disconnection of the faulty line. By placing the loop-closing point of the low-resistance grounding system at the beginning of feeder 1, the disconnected line shares zero-sequence current protection with the NRS feeder. Combined with the arc-suppression coil grounding system, this ensures timely disconnection of the faulty line. Furthermore, by installing zero-sequence current protection on the loop-closing tie line, timely disconnection can be ensured when the loop-closing tie line is grounded, preventing the fault range from expanding.
[0011] This invention also provides a method for controlling the loop-closing and switching operation in a hybrid grounding system of a distribution network, applicable to the aforementioned hybrid grounding system of a distribution network, specifically including the following steps:
[0012] Response to 3(I) 原 +I 倒 ) set Shedding loads to low-resistance grounding systems;
[0013] In response to I max -I C1 -I C2 ≤I Q The load is switched to the arc suppression coil grounding system;
[0014] Among them, I set This refers to the zero-sequence current protection setting value for the existing feeder in a low-resistance grounding system; I 原 I is the zero-sequence current of the original feeder 1. 倒 The zero-sequence current of the reverse-cut circuit; I max I is the maximum capacitive current that the existing arc suppression coil system can compensate for; C1 I represents the capacitive current of the existing arc suppression coil grounding system. C2 I is the capacitor current that is switched into the arc suppression coil system; Q This is the specified maximum residual current value.
[0015] Furthermore, before performing the loop-closing and switching operation, the load to be switched and the maximum allowable load to be switched are calculated, and it is determined whether the load to be switched is less than or equal to the maximum allowable load to be switched; the line length to be switched is calculated, and it is determined whether the line length to be switched is less than the maximum allowable length to be switched.
[0016] In response to the load to be switched being less than or equal to the maximum allowable load to be switched, and the length of the line to be switched being less than the maximum allowable length to be switched, loop switching is permitted.
[0017] In one embodiment, the maximum allowable load to be switched is S0-S1, where S0 is the rated capacity of the bus transformer and S1 is the load carried by the original grounding system.
[0018] In one embodiment, the maximum allowable cut-off length includes the maximum allowable cut-off length into a low-resistance grounding system and the maximum allowable cut-off length into an arc suppression coil grounding system;
[0019] Before switching loads into a low-resistance grounding system, determine whether the length of the line to be switched is less than the maximum allowable line length to be switched into the low-resistance grounding system;
[0020] Before switching loads to the arc suppression coil grounding system, determine whether the length of the line to be switched is less than the maximum allowable line length to be switched into the arc suppression coil grounding system.
[0021] The formula for calculating the maximum line length allowed to be cut into a low-resistance grounding system is as follows:
[0022]
[0023] In the formula, l is the maximum allowable line length for reverse cutting into a low-resistance grounding system, I P The sum of the capacitance currents per unit length of the non-faulty phases, l 原 This is the original length of feeder 1.
[0024] The formula for calculating the maximum allowable line length for reverse cutting into the arc suppression coil grounding system is:
[0025]
[0026] In the formula: l′ is the maximum allowable line length for reverse cutting into the arc suppression coil grounding system; I max I is the maximum capacitive current that the existing arc suppression coil system can compensate for; C1 I represents the capacitive current of the existing arc suppression coil grounding system. Q The specified maximum residual current; I P It is the sum of the capacitance currents of the non-faulty phases per unit length.
[0027] Furthermore, before the loop is closed and switched off, the capacitive current of the hybrid grounding system is calculated, the pre-tuned arc suppression coil is tuned, the capacity and tap of the follow-tuned arc suppression coil are checked in advance, the capacity is expanded for those with insufficient capacity, and the faulty feeder or the loop state is terminated in time for those that are difficult to extinguish the arc, thereby enhancing the reliability of the interconnection operation.
[0028] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the aforementioned method for controlling loop-closing and switching operations in a hybrid grounding system of a power distribution network.
[0029] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned loop-closing and switching operation control method in a hybrid grounding system of a power distribution network. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of a conventional hybrid grounding system for power distribution networks.
[0031] Figure 2 This is a schematic diagram of the structure of the hybrid grounding system of the power distribution network according to an embodiment of this application.
[0032] Figure 3 This is a schematic diagram of a low-resistance grounding system operating under multiple loads according to an embodiment of this application.
[0033] Figure 4 This is a waveform diagram of three times the zero-sequence current of the non-faulty feeder 1 in an embodiment of this application.
[0034] Figure 5 This is a schematic diagram of the operation of a multi-line arc suppression coil grounding system according to an embodiment of this application.
[0035] Figure 6 This is a waveform diagram of the ground fault current in an embodiment of this application.
[0036] Figure 7 This is a schematic diagram of the structure of an electronic device according to an embodiment of this application. Detailed Implementation
[0037] Common grounding methods for open-loop power grids mainly include arc suppression coil grounding, low-resistance grounding, and a hybrid grounding method combining low resistance and arc suppression coils. The circuit diagram for the hybrid grounding method combining low resistance and arc suppression coils is shown below. Figure 1 As shown, a zero-sequence current protection device is installed on the grounding side of the small resistor. The closer the fault point is to the end of the line, the greater the short-circuit impedance, the smaller the corresponding fault current, and the less likely the relay protection is to operate.
[0038] Loop-closing switching, with its characteristic of uninterrupted load shedding, can effectively improve power supply reliability in urban distribution networks with low resistance and arc suppression coil mixed grounding methods. Specifically, loop-closing switching refers to an operational strategy in the current distribution network's "closed-loop planning, open-loop operation" model, which electrically connects two open-loop power grids. Its main advantage is reducing power outage time for users and improving power supply reliability. However, loop-closing switching leads to the short-term coexistence of different grounding systems, increasing the load. If a single-phase ground fault occurs during the loop-closing switching process, the original protection scheme may be inapplicable.
[0039] To address this issue, this application proposes a hybrid grounding system for power distribution networks and a loop-closing reverse-cut operation control method for such a system.
[0040] The technical solution of the present invention will be further described in detail below through specific embodiments.
[0041] Example 1
[0042] This embodiment provides a hybrid grounding system for a power distribution network, such as Figure 2 As shown, it includes a small-resistance grounding system on the left, an arc-suppression coil grounding system on the right, and a loop connection line for connecting the small-resistance grounding system and the arc-suppression coil grounding system.
[0043] The loop connection point between the loop connection line and the small resistance grounding system is located at the beginning of feeder 1, so that the reverse-cut line and the feeder of the small resistance grounding system share a set of zero-sequence current protection.
[0044] Zero-sequence current protection is installed on the side of the closed-loop interconnection line closest to the arc suppression coil grounding system. The side of the closed-loop interconnection line closest to the low-resistance grounding system shares a set of zero-sequence current protection with the feeder of the low-resistance grounding system.
[0045] Compared with the traditional hybrid grounding system of the distribution network, the loop closing point of the low-resistance grounding system is adjusted from the bus to the first end of feeder 1. This can solve the problem that if the arc suppression coil feeder is not equipped with zero-sequence current protection, a large current will also appear at the neutral point of the NRS in the case of incorrect line selection, causing the grounding transformer protection to malfunction and the low-resistance neutral point to be disconnected.
[0046] Meanwhile, a zero-sequence current protection is installed on the side of the loop closing switch near the NES system. The zero-sequence current protection of the NRS feeder near the loop closing tie line is also used as the zero-sequence current protection of the loop closing tie line on the NRS side, so that when a ground fault is detected, the loop closing switch can be cut off in time to end the loop closing and prevent the fault range from expanding.
[0047] Therefore, when a single-phase ground fault occurs on the low-resistance side of the mixed grounding system, the zero-sequence current protection originally installed on the NRS side remains effective, enabling rapid and accurate disconnection of the faulty line. When a single-phase ground fault occurs on the arc suppression coil side of the mixed grounding system, the switching line and the NRS feeder share the zero-sequence current protection, ensuring rapid disconnection of the faulty line. When a single-phase ground fault occurs on the tie line of the mixed grounding system, the zero-sequence current protection of the NRS feeder near the loop tie line is used as the zero-sequence current protection of the loop tie line on the NRS side. The zero-sequence current protection installed on the side of the loop switch near the NES system ensures timely disconnection when the loop tie line is grounded, preventing simultaneous bus grounding of both grounding systems and reducing the expansion of the fault range.
[0048] Example 2
[0049] This embodiment provides a loop-closing and switching operation control method for a hybrid grounding system in a power distribution network, specifically applied to a single-phase grounding fault occurring in the hybrid grounding system of the power distribution network described in Embodiment 1.
[0050] The specific steps are as follows:
[0051] Obtain the zero-sequence current protection setting value I of the original feeder of the low-resistance grounding system. set The maximum capacitive current I that the existing arc suppression coil system can compensate for. max The capacitive current I of the original arc suppression coil grounding system C1 The capacitor current I of the arc suppression coil system is switched inward. C2 The specified maximum residual current value I Q ; Obtain the zero-sequence current I of feeder 1, where the NRS side loop-closing point is located, considering a single-phase ground fault. 原 The zero-sequence current I of the reverse-cut circuit 倒 .
[0052] When I set I 原 I 倒 Satisfy 3(I) 原 +I 倒 ) set When this occurs, it triggers the shearing of loads from the low-resistance grounding system.
[0053] When I max I C1 I C2 I Q Satisfy I max -I C1 -I C2 ≤I Q At that time, the load is switched to the grounding system of the arc suppression coil.
[0054] Understandable, when Figure 3 For example, suppose the original feeder 1 and the switched-off line of the arc suppression coil grounding system share a set of zero-sequence current protection devices. If a single-phase ground fault occurs on line 4, the current flowing through the zero-sequence protection device on the non-faulty feeder 1 will be the sum of the non-faulty phase capacitance currents of the original line and the switched-off line. This value exceeds the zero-sequence current protection setting value of feeder 1, which will cause the protection to malfunction and result in a simultaneous power outage of the switched-off line and feeder 1. However, by adopting the boundary conditions for the switched-off line of the low-resistance system set in this embodiment, it can be ensured that the zero-sequence current protection of the non-faulty line of the NRS system will not malfunction when a single-phase ground fault occurs. By adopting the boundary conditions for the switched-off line of the arc suppression coil system set in this embodiment, it can be ensured that the system will reliably compensate the residual current to below the specified value of 10A when a single-phase ground fault occurs.
[0055] When excessive additional loads are connected to the system, the total system load can exceed the capacity of the 110kV / 10.5kV transformer on the busbar, causing transformer overload. Under prolonged overload operation, the transformer temperature rises, insulation life decreases, and the large load current generates a significant voltage drop across the transformer windings, reducing the output voltage. Since the increase in capacitive current in non-faulty phases depends on the length of the switching line, excessive additional line length can lead to excessive zero-sequence current in non-faulty lines, causing malfunctions in zero-sequence current protection. Therefore, before performing loop-closing switching, it is necessary to limit the load connected to the system and the length of the lines connected.
[0056] To address this issue, this embodiment calculates the load to be switched and the maximum allowable load before performing the loop-closing switching operation, and determines whether the load to be switched is less than or equal to the maximum allowable load; it also calculates the line length to be switched and determines whether the line length to be switched is less than the maximum allowable length.
[0057] Since load shedding is divided into shedding loads into a low-resistance grounding system and shedding loads into an arc suppression coil grounding system, the maximum allowable shedding length also includes the maximum allowable line length for shedding into a low-resistance grounding system and the maximum allowable line length for shedding into an arc suppression coil grounding system.
[0058] Before switching loads into a low-resistance grounding system, determine whether the length of the line to be switched is less than the maximum allowable line length to be switched into the low-resistance grounding system;
[0059] Before switching loads to the arc suppression coil grounding system, determine whether the length of the line to be switched is less than the maximum allowable line length to be switched into the arc suppression coil grounding system.
[0060] In response to the load to be switched being less than or equal to the maximum allowable load to be switched, and the line length to be switched being less than the maximum allowable length to be switched, i.e., when S2≤S0-S1 and L≤l or L≤l′ is satisfied, loop switching is allowed.
[0061] In the formula: S2 is the load to be switched, S0 is the rated capacity of the 110kV / 10.5kV transformer on the busbar; S1 is the load carried by the original grounding system; L is the line length to be switched; 1 is the maximum line length allowed to be switched into the low resistance grounding system; 1′ is the maximum line length allowed to be switched into the arc suppression coil grounding system.
[0062] In practical implementation, the formula for calculating the maximum line length allowed to be switched into a low-resistance grounding system is as follows:
[0063]
[0064] In the formula, l is the maximum allowable line length for reverse cutting into a low-resistance grounding system, I P The sum of the capacitance currents per unit length of the non-faulty phases, l 原 This is the original length of feeder 1.
[0065] The formula for calculating the maximum allowable line length for reverse cutting into the arc suppression coil grounding system is:
[0066]
[0067] In the formula: l′ is the maximum allowable line length for reverse cutting into the arc suppression coil grounding system; I max I is the maximum capacitive current that the existing arc suppression coil system can compensate for; C1 I represents the capacitive current of the existing arc suppression coil grounding system. Q The specified maximum residual current; I P It is the sum of the capacitance currents of the non-faulty phases per unit length.
[0068] by Figure 2 As shown in the example, each grounding system has four feeders. Feeders 1, 2, 4, 5, 6, and 8 are cable lines with lengths of 20km, 4km, and 10km, respectively. Feeders 3 and 7 are mixed lines of cable and overhead lines, with each cable line and overhead line having a length of 10km. The neutral point resistance on the NRS side is set to 10Ω. The line impedance parameters are shown in Table 1.
[0069] Positive sequence resistance (Ω / km) 0.270 0.178 Positive sequence inductance (mH / km) 0.260 1.210 Positive sequence capacitance (μF / km) 0.340 0.015 Zero-sequence resistance (Ω / km) 0.320 0.250 Zero-sequence inductance (mH / km) 1.055 5.540 Zero-sequence capacitance (μF / km) 0.290 0.006
[0070] The feeder load parameters of the low-resistance grounding system are shown in Table 2:
[0071] Active power / MW 0.76 0.69 1.28 1.84 Reactive power / Mvar 0.42 0.35 0.69 0.97
[0072] The feeder load parameters of the arc suppression coil grounding system are shown in Table 3:
[0073] Active power / MW 0.89 0.58 1.65 1.94 Reactive power / Mvar 0.46 0.27 0.84 1.06
[0074] According to the line impedance parameter table, the sum of the ground capacitance current per unit length of the non-faulty phase during a single-phase ground fault is 1.65A. Under normal circumstances, the total length of the cable carried by a single outgoing line of an urban substation will not exceed 25km. The calculated maximum capacitance current is 41.25A. Therefore, the zero-sequence protection setting value on a single outgoing line should be greater than this value. Considering a certain margin, 60A is taken in this embodiment.
[0075] When a single-phase ground fault occurs on the low-resistance side of a hybrid grounding system, the changes in its neutral point current and the zero-sequence current of the faulted line are relatively small compared to a low-resistance grounding system alone. The zero-sequence current protection originally installed on the outgoing line can quickly and accurately disconnect the faulted line and remains effective. At this time, the neutral point current of the NES increases, but the NES can operate with the fault for 1 to 2 hours, and the faulted line on the low-resistance side can be quickly disconnected, restoring normal operation.
[0076] When a single-phase ground fault occurs on the side of the arc suppression coil in a hybrid grounding system, the ground fault current is difficult to be compensated by the arc suppression coil to below the specified value. Therefore, the capacitive current of the hybrid grounding system should be calculated in advance before closing the loop. The pre-tuned arc suppression coil should be tuned in advance, and the capacity and tap of the follow-tuned arc suppression coil should be checked in advance. If the capacity is insufficient, it should be expanded in time. If it is difficult to extinguish the arc, the faulty feeder should be disconnected or the loop should be closed in time to prevent the accident from escalating.
[0077] Under normal circumstances, because zero-sequence current protection is not installed on the arc suppression coil feeder, a large current will also appear at the NRS neutral point in the event of a wrong line selection, causing the grounding transformer protection to malfunction and the low-resistance neutral point to be disconnected; however, in this application, if Figure 2 As shown, the loop closing point on the NRS side is adjusted from the bus to the beginning of feeder 1, so that the reverse-cut line and the feeder of NRS share a set of zero-sequence current protection, which can quickly clear the fault.
[0078] In addition, a single-phase ground fault occurring on the loop connection line can cause the busbars of both grounding systems to be grounded simultaneously, which is the most serious situation. In this application, a zero-sequence current protection is installed on the side of the loop switch near the NES system. The zero-sequence current protection of the NRS feeder near the loop connection line is also used as the zero-sequence current protection of the loop connection line on the NRS side. This allows the loop switch to be cut off in time when a ground fault is detected, thus preventing the fault range from expanding.
[0079] Furthermore, before switching the load to the low-resistance grounding system during a single-phase ground fault, after comprehensively considering the possibility of a single-phase ground fault occurring at the end of the loop switching operation, the total length of the line that can be switched to the NRS without causing the zero-sequence current protection of the non-faulty line to malfunction is calculated.
[0080] Taking the simulation parameters mentioned above as an example, the zero-sequence current protection setting value of feeder 1 is 60A, and the sum of the non-faulty phase capacitance currents per unit length is 1.65A. Therefore, the total line length 1 for the maximum reverse cut-in to NRS can be calculated by the following formula:
[0081]
[0082] In the formula: I P It is the sum of the capacitance currents per unit length of the non-faulty phases; l 原 This is the original length of feeder 1.
[0083] The calculated value is l = 16.36 km.
[0084] To verify the rationality of this switching condition, a 16.36km long cable line from the original NES system was connected to the NRS system. After the switching, a single-phase ground fault occurred on line 4, lasting 100ms. The waveform of the three-times zero-sequence current on the non-faulty feeder 1 is shown below. Figure 4 As shown:
[0085] The simulation results show that the effective value of the three times zero-sequence current of the non-faulted feeder 1 after the reversal is 59.88A, and the error with the zero-sequence protection setting value of 60A is only 0.2%. Therefore, it can be considered that the maximum line length reversal condition proposed in this paper is reasonable.
[0086] When switching the load to the arc suppression coil grounding system during a single-phase ground fault, Figure 5 For example, to ensure that the ground fault current can be compensated to below the specified 10A in a timely manner, the load shedding to the NES must meet the following conditions:
[0087] I max -I C1 -I C2 ≤I Q
[0088] In the formula: I max The maximum capacitive current that the existing arc suppression coil system can compensate for; I C1 This refers to the original NES capacitor current; I C2 I is the capacitor current that is switched into the arc suppression coil system; Q The specified maximum residual current is typically 10A.
[0089] Taking the NES system parameters in this article as an example, the arc suppression coil capacity of the original NES grounding system is 630kVA. When it is working at its maximum setting, the corresponding inductance value L m It can be calculated using the following formula:
[0090]
[0091] In the formula: U φQ is the phase voltage; Q is the arc suppression coil capacity.
[0092] Calculations show that the inductance of the arc suppression coil is 0.186H, and the compensable capacitor current is 103.93A. Therefore, the maximum shear length l′ is as follows:
[0093]
[0094] If we take the feeder parameters in this article as a reference, the maximum reverse-cut line length can be calculated to be 25.04km.
[0095] To verify the rationality of the loop closure condition, a 25.04km long cable line from the original NRS system was connected to the NES system. A metallic single-phase ground fault occurred at the end of the feeder, lasting 100ms. The current at the fault point was observed to ensure it was compensated to the specified value of 10A. The simulation waveform is shown below. Figure 6 As shown.
[0096] Depend on Figure 6 It can be seen that, under the condition of the maximum reverse-cut line length, the effective value of the current at the ground fault point is 10.42A, which is 4.2% less than the theoretical value of 10A. The error is less than 5%, so the closed-loop reverse-cut condition proposed in this paper can be considered reasonable.
[0097] Example 3
[0098] This embodiment provides an electronic device, such as... Figure 7 As shown, Figure 7 The illustrated electronic device 600 includes a processor 601 and a memory 603. The processor 601 and the memory 603 are connected, for example, via a bus 602. The structure of this electronic device 600 does not constitute a limitation on the embodiments of this application.
[0099] Processor 601 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. Processor 601 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.
[0100] Bus 602 may include a pathway for transmitting information between the aforementioned components. Bus 602 may be a PCI bus or an EISA bus, etc. Bus 602 may be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 6 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.
[0101] The memory 603 may be a ROM or other type of static storage device capable of storing static information and instructions, RAM or other type of dynamic storage device capable of storing information and instructions, or it may be an EEPROM, CD-ROM or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.
[0102] The memory 603 stores the application code that executes the scheme of this application, and its execution is controlled by the processor 601. The processor 601 executes the application code stored in the memory 603 to implement... Figure 4 The loop-closing and switching operation control method provided in the hybrid grounding system of the power distribution network shown in Embodiment 2.
[0103] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned loop-closing and switching operation control method in a hybrid grounding system of a power distribution network.
[0104] 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 them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.
Claims
1. A loop-closing and switching operation control method for a hybrid grounding system in a power distribution network, applied to a hybrid grounding system in a power distribution network, wherein the hybrid grounding system in a power distribution network includes a small-resistance grounding system on the left, an arc-suppression coil grounding system on the right, and a loop-closing tie line for connecting the small-resistance grounding system and the arc-suppression coil grounding system; in, The loop connection point between the loop connection line and the small resistance grounding system is located at the beginning of feeder 1, so that the reverse-cut line and the feeder of the small resistance grounding system share a set of zero-sequence current protection. The closed-loop interconnection line is equipped with zero-sequence current protection on the side closest to the arc suppression coil grounding system, and the side of the closed-loop interconnection line closest to the low-resistance grounding system shares a set of zero-sequence current protection with the feeder of the low-resistance grounding system; characterized by including the following steps: In response to Shedding loads to low-resistance grounding systems; In response to The load is switched to the arc suppression coil grounding system; Among them, I set This refers to the zero-sequence current protection setting value for the existing feeder in a low-resistance grounding system; I 原 I is the zero-sequence current of feeder 1. 倒 The zero-sequence current of the reverse-cut circuit; I max The maximum capacitive current that the existing arc suppression coil system can compensate for; I C1 I represents the capacitive current of the existing arc suppression coil grounding system. C2 I is the capacitor current that is switched into the arc suppression coil system; Q The specified maximum residual current; Before performing the loop-closing and switching operation, calculate the load to be switched, the maximum allowable load to be switched, and determine whether the load to be switched is less than or equal to the maximum allowable load to be switched; calculate the line length to be switched, and determine whether the line length to be switched is less than the maximum allowable length to be switched. In response to the load to be switched being less than or equal to the maximum allowable load to be switched, and the length of the line to be switched being less than the maximum allowable length to be switched, loop switching is permitted; The maximum permissible reverse cutting length includes the maximum line length permissible for reverse cutting into a low-resistance grounding system and the maximum line length permissible for reverse cutting into an arc suppression coil grounding system; Before switching loads into a low-resistance grounding system, determine whether the length of the line to be switched is less than the maximum allowable line length to be switched into the low-resistance grounding system; Before switching loads to the arc suppression coil grounding system, determine whether the length of the line to be switched is less than the maximum allowable line length to be switched into the arc suppression coil grounding system.
2. The method for controlling loop-closing and switching operations in a hybrid grounding system of a distribution network according to claim 1, characterized in that, The maximum allowable load for reverse shearing is Where S0 is the rated capacity of the bus transformer; S1 is the load carried by the original grounding system.
3. The method for controlling loop-closing and reverse-switching operation in a hybrid grounding system of a distribution network according to claim 1, characterized in that, The formula for calculating the maximum line length allowed to be switched into a low-resistance grounding system is: ； In the formula, To allow the maximum line length to be cut back into a low-resistance grounding system, I P The sum of the capacitance currents per unit length of the non-faulty phases, l 原 This is the original length of feeder 1.
4. The method for controlling loop-closing and reverse-switching operation in a hybrid grounding system of a distribution network according to claim 1, characterized in that, The formula for calculating the maximum allowable line length for reverse cutting into the arc suppression coil grounding system is: ； In the formula: l′ is the maximum allowable line length for reverse cutting into the arc suppression coil grounding system, I max The maximum capacitive current that the existing arc suppression coil system can compensate for; I C1 I represents the capacitive current of the existing arc suppression coil grounding system. Q The specified maximum residual current; I P It is the sum of the capacitance currents of the non-faulty phases per unit length.
5. The method for controlling loop-closing and switching operations in a hybrid grounding system of a distribution network according to any one of claims 2-4, characterized in that, Before closing the loop and switching off, the capacitive current of the hybrid grounding system is calculated, the pre-tuned arc suppression coil is tuned, the capacity and tap of the follow-tuned arc suppression coil are checked in advance, the capacity is expanded for those with insufficient capacity, and the faulty feeder or the loop closing state is terminated in time for those that are difficult to extinguish the arc.
6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the loop-closing and switching operation control method in the hybrid grounding system of the distribution network as described in any one of claims 1-5.
7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the loop-closing and switching operation control method in the hybrid grounding system of the distribution network as described in any one of claims 1-5.