CN215772536U - Resistance grounding system - Google Patents

Abstract

The utility model discloses a resistance grounding system, which comprises at least two operating systems and a section switch, wherein each operating system comprises a bus, a main transformer, a grounding module, a control module, a first protection module, a partition and a second protection module; the first protection module comprises a first switch unit and a second switch unit; the second protection module comprises a third switching unit; the grounding module comprises a first impedance unit, a second impedance unit, a third impedance unit and a fourth impedance unit; the first impedance unit is composed of only a first resistor, the second impedance unit is composed of a second resistor and a second resistor switch, and the third impedance unit is composed of a third resistor and a third resistor switch. The resistance grounding system determines the occurrence of the grounding fault and cuts off the fault by utilizing the relation of the zero sequence current and the change rule of the resistance value of the grounding module, and the sensitivity is higher. The embodiment of the utility model relates to the field of power system control.

Description

Resistance grounding system

Technical Field

The embodiment of the utility model relates to the field of power system control, in particular to a resistance grounding system.

Background

The power distribution network is used as the last link of the power system, and the significance of safe operation of the power distribution network and fault removal after a fault occurs is great.

With the rapid development of urban economy, a small-resistance grounding system is adopted on a large scale for cables in an urban power distribution network, but when zero-sequence current generated when a grounding fault occurs is too small and is smaller than a setting value, the protection is refused and the fault cannot be removed, the fault exists for a long time, the power supply quality is seriously influenced, and the loss of power supply equipment is more serious.

SUMMERY OF THE UTILITY MODEL

The utility model provides a resistance grounding system, which is used for determining the existence of a grounding fault in time and removing the grounding fault so as to ensure the safety of power supply equipment.

The utility model provides a resistance grounding system, which comprises at least two operating systems and a section switch connected with the adjacent operating systems, wherein each operating system comprises a bus, a main transformer corresponding to the bus, a grounding module, a control module, a first protection module, at least one interval and a second protection module arranged in the interval; the first protection module comprises a first switch unit and a second switch unit, the grounding module is connected with the bus through the first switch unit, and the bus is connected with the main transformer through the second switch unit; the second protection module comprises a third switching unit, and the third switching unit is used for controlling the connection state of the grounding module and the corresponding resistor;

in any one of the operating systems, the control module is respectively connected with the first switch unit, the second switch unit and the section switch;

the control module is electrically connected with the grounding module, the grounding module comprises a parallel group and a fourth impedance unit, the parallel group is formed by connecting a first impedance unit, a second impedance unit and a third impedance unit in parallel, the first end of the parallel group is electrically connected with the first switch unit, the second end of the parallel group is electrically connected with the first end of the fourth impedance unit, and the second end of the fourth impedance unit is grounded; the first impedance unit is composed of only a first resistor, the second impedance unit is composed of a second resistor and a second resistor switch, and the third impedance unit is composed of a third resistor and a third resistor switch.

Further, the resistance value of the first resistor is equal to the resistance value of the second resistor and is 2 times of the resistance value of the fourth impedance unit, the resistance value of the third resistor is zero, and the control module controls the switching-in/switching-out state of the second resistor switch or the third resistor switch to realize regular change of the total resistance value.

Further, the second resistance switch and the third resistance switch are both circuit breakers.

Further, the first protection module comprises a grounding transformer and a first current acquisition unit, and the second protection module further comprises a second current acquisition unit;

one end of the grounding transformer is electrically connected with the first switch unit, and the other end of the grounding transformer is electrically connected with the first end of the first impedance unit, the second impedance unit and the third impedance unit which are connected in parallel;

one end of the first current acquisition unit is electrically connected with the second end of the fourth impedance unit, the other end of the first current acquisition unit is grounded, and the first current acquisition unit is used for acquiring the current of the first protection module;

the second current collecting units are arranged on the corresponding spaced lines.

Furthermore, the operation system further comprises a voltage acquisition module, the voltage acquisition module is respectively electrically connected with the control module and the bus, and the voltage acquisition module is used for acquiring the zero sequence voltage of the operation system.

The control module of the resistance grounding system provided by the embodiment of the utility model collects the position information of the first switch unit, the second switch unit and the section switch, determines the operation mode of the system according to the position information and transmits the operation mode to the first protection module and the second protection module, the control module also generates a control signal according to the zero sequence voltage, the grounding module controls the resistance value of the grounding module to change according to the rule according to the control signal and transmits the resistance value change information of the grounding module to the first protection module and the second protection module, the second protection module controls the third switch unit to act and generate an action signal according to the relation between the change rule of the zero sequence current and the change rule of the resistance value of the grounding module, and the first protection module controls the first switch unit to act and generate an action signal according to the relation between the change rule of the zero sequence current and the change rule of the resistance value of the grounding module, the operation mode, the action signal, the first current set value and the second current set value, The second switching unit and the section switch act. When a system has a ground fault, the first protection module and the second protection module can control corresponding switch units to act to remove the fault, so that safe operation of the system is ensured, meanwhile, most of the prior art sets a current setting value, when the acquired zero-sequence current of the system is greater than the set current setting value, the ground fault is considered to occur, and the situation that the ground fault occurs but the zero-sequence current is smaller is easy to cause protection failure.

According to the size of the grounded zero sequence resistive current, the change characteristics of the grounded line fault zero sequence resistive current are observed by utilizing the regular change characteristics of the zero sequence resistive current caused by the combined switching of a plurality of grounded resistors during grounding, and the spaced branch circuits with consistent change characteristics are fault circuits, so that the fault branch circuits with high resistance and grounding are found and cut off, and the safety of a power supply system and human bodies is ensured.

In addition, the grounding module comprises a first impedance unit, a second impedance unit and a third impedance unit, but only two resistance switches are used for adjustment, namely one resistance is normally input, operation switches are reduced, the number of the adjustable switches is reduced, the investment is low, the adjustment is convenient, and the structure is simple. The combined size of the resistors can also be chosen differently.

Drawings

Fig. 1 is a schematic structural diagram of a resistance grounding system provided in the present invention.

Fig. 2 is a schematic diagram of a network communication structure of a resistance grounding system provided in the present invention.

Fig. 3 is a schematic structural diagram of a resistance grounding system provided in the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the utility model and are not limiting of the utility model. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Fig. 1 is a schematic structural diagram of a resistance grounding system provided by the present invention, and referring to fig. 1, the resistance grounding system includes at least two operating systems and a section switch L1 connecting adjacent operating systems, and the operating systems include: the bus comprises a bus 100, a main transformer T1 corresponding to the bus, a grounding module 200, a control module 300, a first protection module 400, at least one interval and a second protection module 500 arranged in the interval; the first protection module 400 comprises a first switch unit L2 and a second switch unit L3, the grounding module 200 is connected with the bus bar 100 through the first switch unit L2, the bus bar 100 is connected with the main transformer T1 through the second switch unit L3, the first switch unit L2 is used for controlling the connection state of the grounding module 200 and the bus bar 100, and the second switch unit L3 is used for controlling the connection state of the bus bar 100 and the corresponding main transformer T1; the second protection module 500 includes a third switching unit L4, the third switching unit L4 is used for controlling the connection state of the ground module 200 and the corresponding resistor;

in any operating system, the control module 300 is connected to the first switch unit L2, the second switch unit L3 and the section switch L1, respectively, and the control module 300 is configured to collect position information of the first switch unit L2, the second switch unit L3 and the section switch L1, determine an operating mode of the system according to the position information, and send the operating mode to the first protection module 400, the second protection module 500 and the control module 300 of the adjacent operating system; the control module 300 is electrically connected with the grounding module 200 and is used for generating a control signal according to the zero sequence voltage; the grounding module 200 is used for controlling the change of the self resistance value according to the control signal; the second protection module 500 is configured to control the third switching unit L4 to act and generate an action signal according to a relationship between a change rule of the zero sequence current of the second protection module and a change rule of the resistance of the ground module 200; the first protection module 400 is configured to control the first switch unit L2, the second switch unit L3, and the section switch L1 to operate according to a relationship between a change rule of the zero sequence current and a change rule of the resistance of the ground module 200, an operation mode, an operation signal, a first current set value, and a second current set value.

The first switch unit L2, the second switch unit L3, the third switch unit L4, and the section switch L1 may be contactors, circuit breakers, or other switches, the control module 300 may be a single chip microcomputer, a circuit structure, or other devices capable of achieving a control function, and the grounding module 200 may be a circuit structure composed of resistors.

The position information of the first switch unit L2 includes two cases of the first switch unit L2 being in the on position and in the off position, the position information of the second switch unit L3 includes two cases of the second switch unit L3 being in the on position and in the off position, and the position information of the section switch L1 includes two cases of the section switch L1 being in the on position and in the off position. The operation mode of the system comprises independent operation and parallel operation. When the position information of the section switch L1 is collected to be positioned at the separation position and the first switch unit L2 and the second switch unit L3 are both positioned at the closing position, the system operates independently; when the collection section switch L1 is in the closed position, the system is in parallel operation. When the system runs in parallel, the system can be subdivided into a plurality of modes, for example, the mode one: when the first switch unit L2 and the second switch unit L3 connected with the bus 100 are collected to be located at the closed position, the bus 100 where the first protection module 400 and the main transformer T1 are located and the adjacent bus 100 in another section are determined to run in parallel; the second method comprises the following steps: when the first switch unit L2 connected with the bus 100 is collected to be located at the closing position and the second switch unit L3 is collected to be located at the separating position, the first protection module 400 is determined to run in parallel with the other adjacent section of bus 100 through the bus 100; the third method comprises the following steps: when the first switch unit L2 connected with the bus 100 is in the open position and the second switch unit L3 is in the closed position, the main transformer T1 is determined to run in parallel with the adjacent other section of bus 100 through the bus 100.

The control signals include resistance value change control signals and resistance value invariable control signals, and when the zero sequence voltage of the system is greater than a set voltage threshold, the control module 300 generates resistance value change control signals; when the zero sequence voltage of the system is less than or equal to the set voltage threshold, the control module 300 generates a resistance-invariant control signal. The grounding module 200 can adjust the resistance value thereof according to the control signal, when the system normally operates, the grounding module 200 is connected to the system with the maximum resistance value, when the grounding module 200 receives the resistance value change control signal, the grounding module 200 controls the resistance value thereof to change according to a preset rule, the preset rule can be that the resistance value thereof is firstly decreased and then increased, wherein the decreased and increased values can be changed in a multiple rule of a certain set value, exemplarily, the resistance value of the grounding module 200 can be changed from 12 ohms to 8 ohms to 4 ohms to 12 ohms and in a multiple of 4 ohms; when the grounding module 200 receives the resistance-constant control signal, the grounding module 200 keeps the maximum resistance value added during operation unchanged.

The action signals include a first action signal, a second action signal and a third action signal, and when the change rule of the zero sequence current of the second protection module 500 matches the change rule of the resistance value of the grounding module 200, the second protection module 500 controls the third switching unit L4 to be turned off and generates the first action signal; when the change rule of the zero sequence current of the second protection module 500 does not match the change rule of the resistance of the grounding module 200, the second protection module 500 controls the third switching unit L4 to be inactive and generates a second action signal; when the relationship between the change rule of the zero sequence current of the second protection module 500 and the change rule of the resistance of the grounding module 200 matches and the second protection module 500 controls the third switching unit L4 not to act, a third action signal is generated. The matching of the change law of the zero-sequence current and the change law of the resistance value of the grounding module 200 means that when the resistance value of the grounding module 200 is decreased and then increased according to the law, the zero-sequence current is increased and then decreased according to the law, and in the process that the zero-sequence current is increased and then decreased, the zero-sequence current value is larger than the current setting value to determine that the ground fault occurs.

Fig. 1 schematically illustrates a case where the first operating system 001 and the second operating system 002 comprise two operating systems, and each system comprises one bay in an exemplary manner, and in other embodiments, a plurality of operating systems and a plurality of bays may be included. Fig. 2 is a schematic diagram of a network communication structure of a resistance grounding system according to an embodiment of the present invention, referring to fig. 2, a control module 300, a first protection module 400, a second protection module 500, a main transformer T1, and a section switch L1 in all the systems are all connected to an ethernet and synchronous time synchronization network, and perform information interaction through the network, for example, after determining a system operation mode, the control module 300 of a first operating system 001 may transmit the operation mode to the first protection module 400, the control module 300 of a second operating system 002 or other devices connected to the network through the network.

With reference to fig. 1, when the control module 300 of the first operating system 001 (or the second operating system 002) acquires the position information of the section switch L1, the first switch unit L2, and the second switch unit L3 of the system to determine that the system operates independently, the ground module 200 accesses the system with the maximum resistance value, when the control module 300 acquires that the zero-sequence voltage of the system is greater than the set voltage threshold, it indicates that the system has a ground fault, and when the zero-sequence voltage is still greater than the set voltage threshold after the first set time, it indicates that the ground fault is not cut off, at this time, the control module 300 controls the resistance value of the ground module 200 to decrease and then increase, it is noted that the resistance value of the ground module 200 is spaced by the second set time between each two adjacent changes, the control module 300 transmits the corresponding time of the change and the change of the resistance value of the ground module 200 to the first protection module 400 and the second protection module 500 through the communication network, after receiving the information of the control module 300, the first protection module 400 and the second protection module 500 respectively collect the zero sequence currents of themselves, and control the corresponding switching actions according to the relationship between the change rule of the zero sequence current and the change rule of the resistance value of the grounding module 200, and the second protection module 500 generates an action signal after the third switching unit L4 is completed. When the change law of the zero-sequence current of the first protection module 400 is matched with the change law of the resistance value of the grounding module 200, and meanwhile, after a third set time, an action signal of the second protection module 500 is received through the communication network as a second action signal, it is determined that the bus 100 or the main transformer T1 branch or the first protection module 400 branch has a ground fault, and the first protection module 400 controls the first switching unit L2 and the second switching unit L3 to be disconnected, so that the fault is removed; when the change rule of the zero-sequence current of the first protection module 400 matches the change rule of the resistance value of the ground module 200, and meanwhile, after a third set time, an action signal of the second protection module 500 is received as a third action signal through the communication network, it is determined that a ground fault occurs at an interval corresponding to the second protection module 500 of the system, the third switching unit L4 is not disconnected, the fault is not removed by the second protection module 500, and at this time, the first protection module 400 controls the first switching unit L2 and the second switching unit L3 to be disconnected, so that the fault is removed; when the change rule of the zero-sequence current of the first protection module 400 matches the change rule of the resistance value of the ground module 200, and meanwhile, after the third set time, the action signal received via the communication network from the second protection module 500 is the first action signal, and the zero-sequence current of the second protection module 500 is greater than the first current set value, it is determined that the ground fault occurs in the interval corresponding to the second protection module 500 of the system, and the third switching unit L4 is disconnected but the fault still exists after the switch is disconnected, at this time, the first protection module 400 controls the first switching unit L2 and the second switching unit L3 to be disconnected, and the fault is removed.

After the control module 300 collects the position information of the sectionalizing switch L1, the first switch unit L2 of the first operating system 001, the second switch unit L3 of the first operating system 001, the first switch unit L2 of the second operating system 002 and the second switch unit L3 of the second operating system 002, it is determined that the first operating system 001 and the second operating system 002 both operate in parallel in the same manner, i.e. the main transformer T1 and the first protection module 400 of the first operating system 001 and the main transformer T1 and the first protection module 400 of the second operating system 002 operate in parallel through the bus, when the control module 300 of any system obtains that the zero sequence voltage of the system is greater than the set voltage threshold, it is indicated that the system has a ground fault, and when the zero sequence voltage is still greater than the set voltage threshold after the first set time, it is indicated that the ground fault is not removed, at this time, the control module 300 of the first operating system 001 and the control module 300 of the second operating system 002 respectively control the ground modules 200 of the respective systems The resistance value is decreased progressively and then increased progressively, the control module 300 of each operating system transmits the change of the resistance value of the grounding module 200 of the operating system and the corresponding time during the change to the first protection module 400 of the operating system and the second protection module 500 of the operating system through the network, after receiving the information of the control module 300, the first protection module 400 of the operating system and the second protection module 500 of the operating system respectively collect the zero sequence current of the operating system and control the corresponding switching action according to the relation between the change rule of the zero sequence current and the change rule of the resistance value of the grounding module 200 of the operating system, and the second protection module 500 of the operating system generates an action signal after the action of the third switching unit L4 is completed. When the change law of the zero-sequence current of the first protection module 400 of a certain operating system is matched with the change law of the resistance value of the grounding module 200 of the self operating system, and meanwhile, after a third set time, an action signal of the second protection module 500 of the self operating system is received through a communication network and is a second action signal, it is determined that a grounding fault occurs on the bus 100 or the main transformer T1 branch or the first protection module 400 branch of the certain operating system, the control module 300 controls the section switch L1 to be switched off, and after a set settable time, the first protection module 400 obtains the zero-sequence current value of the first protection module 400, when the zero-sequence current of the first protection module 400 is smaller than or equal to the second set current value, it is determined that the grounding fault occurs on another operating system, and the first switch unit L2 and the second switch unit L3 of the self operating system do not act; when the zero sequence current of the first protection module 400 is greater than the second set current value, it is determined that the ground fault occurs in the present operating system, and the first protection module 400 controls the first switching unit L2 and the second switching unit L3 to be turned off, so as to remove the fault. When the change law of the zero sequence current of the first protection module 400 of a certain operating system matches the change law of the resistance value of the grounding module 200 of the operating system, and at the same time, after a third set time, the action signal of the second protection module 500 received through the communication network is a third action signal, it is determined that the ground fault occurs at the interval corresponding to the second protection module 500 and the third switching unit L4 is not opened to remove the fault, at this time, the first protection module 400 of the operating system which sends the third action signal controls the first switching unit L2, the second switching unit L3 and the section switch L1 of the operating system to be opened, and the first switching unit L2 and the second switching unit L3 of the operating system which does not send the third action signal do not act. When the change rule of the zero sequence current of the first protection module 400 of a certain operation system is matched with the change rule of the resistance value of the grounding module 200 of the own operation system, meanwhile, after the third set time, the action signal of the second protection module 500 received via the communication network is the first action signal and the zero sequence current of the first protection module 400 is greater than 50% of the first set current value, it is determined that the interval corresponding to the second protection module 500 has a ground fault and the third switching unit L4 is opened but the fault still exists after the switch is opened, and at this time, the first protection module 400 of the operating system which sends the first operation signal and has the zero-sequence current value greater than 50% of the first set current value controls the first off unit L2, the second switching unit L3 and the section switch L1 of the operating system to be turned off, and the first off unit L2 and the second switching unit L3 of the operating system which does not send the first operation signal do not operate.

After the control module 300 collects the position information of the sectionalizing switch L1, the first switch unit L2 of the first operating system 001, the second switch unit L3 of the first operating system 001, the first switch unit L2 of the second operating system 002 and the second switch unit L3 of the second operating system 002, it is determined that the first operating system 001 and the second operating system 002 operate in parallel in a first mode, that is, the first protection module 400 of the first operating system 001 operates in parallel with the main transformer T1 of the second operating system 002 and the first protection module 400 of the second operating system 002 through a bus, when the zero sequence voltage obtained by the control module 300 of any operating system is greater than the set voltage threshold, it is indicated that the system has a ground fault, and when the zero sequence voltage is still greater than the set voltage threshold after the first set time, it is indicated that the ground fault is not removed, at this time, the control module 300 of the first operating system 001 and the control module 300 of the second operating system 002 respectively control each of the first operating system 001 and the second operating system 002 The resistance value of the grounding module 200 of the self-running system is decreased progressively and then increased progressively, the control module 300 of each running system transmits the change of the resistance value of the grounding module 200 of the self-running system and the corresponding time during the change to the first protection module 400 of the self-running system and the second protection module 500 of the self-running system through the network, after receiving the information of the control module 300 of the self-running system, the first protection module 400 of the self-running system and the second protection module 500 of the self-running system respectively collect the zero sequence current of the self-running system and control the corresponding switch action according to the relation between the change rule of the zero sequence current and the change rule of the resistance value of the grounding module 200 of the self-running system, and the third switch unit L4 of the second protection module 500 of the self-running system generates an action signal after the action is completed. When the change law of the zero sequence current of the first protection module 400 of a certain operating system is matched with the change law of the resistance value of the grounding module 200 of the self operating system, and meanwhile, after a third set time, an action signal of the second protection module 500 of the self operating system is received as a second action signal through the communication network, it is determined that a grounding fault occurs in a bus or a main transformer T1 branch or a first protection module 400 branch of the certain operating system, the control module 300 of the first operating system 001 controls the section switch L1 and the first switch unit L2 to be disconnected, the control module 300 of the second operating system 002 controls the section switch L1 to be disconnected and after a set settable time, the first protection module 400 of the second operating system 002 obtains the zero sequence current value thereof, and when the zero sequence current of the first protection module 400 of the second operating system 002 is less than or equal to the second set current value, it is determined that the grounding fault occurs in the first operating system, the first switching unit L2 and the second switching unit L3 of the second operating system 002 do not operate; when the zero sequence current of the first protection module 400 of the second operation system 002 is greater than the second set current value, it is determined that the ground fault occurs in the second operation system 002, and the first protection module 400 of the second operation system 002 controls the first switching unit L2 and the second switching unit L3 to be turned off, so that the fault is removed. When the change law of the zero-sequence current of the first protection module 400 of a certain operating system matches the change law of the resistance value of the grounding module 200 of the self operating system, and at the same time, after a third set time, the action signal of the second protection module 500 is received as a third action signal through the communication network, it is determined that the ground fault occurs at the interval corresponding to the second protection module 500 and the third switching unit L4 is not opened to remove the fault, at this time, the first protection module 400 of the operating system which sends the third action signal controls the first switching unit L2, the second switching unit L3 and the section switch L1 to be opened (if the second protection module 500 of the first operating system 001 sends the third action signal, the first protection module 400 of the first operating system 001 only controls the first switching unit L2 and the section switch L1 of the system to be opened), and the first switching unit L2, the section switch L8538 of the operating system which does not send the third action signal, The second switching unit L3 does not operate (if the second protection module 500 of the first operating system 001 does not issue the third operation signal, the first switching unit L2 of the first operating system 001 does not operate). When the change rule of the zero-sequence current of the first protection module 400 of a certain operating system matches the change rule of the resistance value of the grounding module 200 of the operating system, and after a third set time, the action signal received via the communication network from the second protection module 500 is the first action signal and the zero-sequence current of the first protection module 400 is greater than 50% of the first set current value, it is determined that the interval corresponding to the second protection module 500 has a ground fault and the fault still exists after the third switching unit L4 is turned off but the switch is turned off, and at this time, the first protection module 400 of the operating system which sends the first action signal and has a zero-sequence current value greater than 50% of the first set current value controls the first switching unit L2, the second switching unit L3 and the section switch L1 to be turned off (if the second protection module 500 of the first operating system 001 sends the first action signal and has a zero-sequence current value greater than 50% of the first set current value, the first protection module 400 of the first operating system 001 may control only the first switch unit L2 and the sectionalizing switch L1 of the system to be turned off), and the first switch unit L2 and the second switch unit L3 of the operating system which do not send the first action signal do not act (if the second protection module 500 of the first operating system 001 does not send the first action signal, the first switch unit L2 of the first operating system 001 does not act).

After the control module 300 collects the position information of the sectionalizing switch L1, the first switch unit L2 of the first operating system 001, the second switch unit L3 of the first operating system 001, the first switch unit L2 of the second operating system 002 and the second switch unit L3 of the second operating system 002, it is determined that the first operating system 001 and the second operating system 002 operate in parallel in a mode one, that is, the first protection module 400 and the main transformer T1 of the first operating system 001 operate in parallel with the first protection module 400 of the second operating system 002 through a bus, and when the control module 300 of any operating system obtains that the zero sequence voltage of the system is greater than the set voltage threshold, it is indicated that the system has a ground fault, and when the zero sequence voltage is still greater than the set voltage threshold after the first set time, it is indicated that the ground fault is not removed, at this time, the control module 300 of the first operating system 001 and the control module 300 of the second operating system 002 respectively control the ground modules of the respective systems 200, the resistance value of each operating system is decreased progressively and then increased progressively, the control module 300 of each operating system transmits the change of the resistance value of the grounding module 200 of the operating system and the corresponding time during the change to the first protection module 400 of the operating system and the second protection module 500 of the operating system through the network, after receiving the information of the control module 300 of the operating system, the first protection module 400 of the operating system and the second protection module 500 of the operating system respectively collect the zero sequence current of the operating system and control the corresponding switching action according to the relation between the change rule of the zero sequence current and the change rule of the resistance value of the grounding module 200 of the operating system, and the third switching unit L4 of the second protection module 500 of the operating system generates an action signal after finishing the action. When the change law of the zero-sequence current of the first protection module 400 of a certain operating system is matched with the change law of the resistance value of the grounding module 200 of the self operating system, and an action signal of the second protection module 500 of the self operating system is received as a second action signal through the communication network after a third set time, it is determined that a grounding fault occurs in a bus or a main transformer T1 branch or a first protection module 400 branch of the certain operating system, the control module 300 of the second operating system 002 controls the section switch L1 and the first switching unit L2 of the second operating system 002 to be disconnected, the control module 300 of the first operating system 001 controls the section switch L1 to be disconnected and after a settable time is set, the first protection module 400 of the first operating system 001 obtains the zero-sequence current value thereof, and when the zero-sequence current value of the first protection module 400 of the first operating system 001 is less than or equal to the second set current value, determining that the ground fault occurs in the second operating system 002, and the first switching unit L2 and the second switching unit L3 of the first operating system 001 do not act; when the zero-sequence current of the first protection module 400 of the first operating system 001 is greater than the second set current value, it is determined that the ground fault occurs in the first operating system 001, and the first protection module 400 of the first operating system 001 controls the first switching unit L2 and the second switching unit L3 to be turned off, thereby removing the fault. When the change law of the zero-sequence current of the first protection module 400 of a certain operating system matches the change law of the resistance value of the grounding module 200 of the self operating system, and after a third set time, it is determined that the action signal of the second protection module 500 of the self operating system received through the communication network is the third action signal, and it is determined that the ground fault occurs at the interval corresponding to the second protection module 500 and the third switch unit L4 is not turned off to remove the fault, at this time, the first protection module 400 of the operating system which sends the third action signal controls the first switch unit L2, the second switch unit L3, and the section switch L1 to be turned off (if the second protection module 500 of the second operating system 002 sends the third action signal, the first protection module 400 of the second operating system 002 only controls the first switch unit L2 and the section switch L1 of the self system to be turned off), the first switch unit L2, the section switch L1 of the operating system which does not send the third action signal, The second switching unit L3 does not act (if the second protection module 500 of the second operating system 002 does not issue the third action signal, the first switching unit L2 of the second operating system 002 does not act). When the change rule of the zero-sequence current of the first protection module 400 of a certain operating system matches the change rule of the resistance value of the grounding module 200 of the operating system, and after a third set time, the action signal received via the communication network from the second protection module 500 is the first action signal and the zero-sequence current of the first protection module 400 is greater than 50% of the first set current value, it is determined that the ground fault occurs in the interval corresponding to the second protection module 500, and the fault still exists after the third switching unit L4 is turned off but the switch is turned off, at this time, the first protection module 400 of the operating system which sends the first action signal and has a zero-sequence current value greater than 50% of the first set current value controls the first switching unit L2, the second switching unit L3 and the section switch L1 to be turned off (if the second protection module 500 of the second operating system 002 sends the first action signal and has a zero-sequence current value greater than 50% of the first set current value, the first protection module 400 of the second operating system 002 only controls the first switch unit L2 and the sectionalizing switch L1 of the system to be turned off), the first switch unit L2 and the second switch unit L3 of the operating system which do not send out the first action signal do not act (if the second protection module 500 of the second operating system 002 does not send out the first action signal, the first switch unit L2 of the second operating system 002 does not act).

In this embodiment, the first setting time, the second setting time, the third setting time, the voltage threshold, the current setting value, the first current setting value, and the second current setting value may all be set according to requirements.

The control module of the resistance grounding system provided in this embodiment collects position information of the first switch unit, the second switch unit and the section switch, determines an operation mode of the system according to the position information, and transmits the operation mode to the first protection module and the second protection module, the control module further generates a control signal according to the zero-sequence voltage, the grounding module controls a resistance value of the grounding module to change according to a rule according to the control signal and transmits resistance value change information of the grounding module to the first protection module and the second protection module, the second protection module controls the third switch unit to operate and generate an action signal according to a relation between a change rule of the zero-sequence current and a change rule of the resistance value of the grounding module, the first protection module controls the first switch unit according to a relation between a change rule of the zero-sequence current and a change rule of the resistance value of the grounding module, the operation mode, the action signal, a first current setting value and a second current setting value, The second switching unit and the section switch act. When a system has a ground fault, the first protection module and the second protection module can control corresponding switch units to act to remove the fault, so that safe operation of the system is ensured, meanwhile, most of the prior art sets a current setting value, when the acquired zero-sequence current of the system is greater than the set current setting value, the ground fault is considered to occur, and the situation that the ground fault occurs but the zero-sequence current is smaller is easy to cause protection failure.

Fig. 3 is a schematic structural diagram of a resistance grounding system provided in the present invention, referring to fig. 3, in an embodiment, the control module is electrically connected to the grounding module, the grounding module 200 includes a parallel group and a fourth impedance unit 240, the parallel group is connected in parallel by a first impedance unit 210, a second impedance unit 220 and a third impedance unit 230, a first end of the parallel group is electrically connected to the first switch unit L2, a second end of the parallel group is electrically connected to a first end of the fourth impedance unit 240, and a second end of the fourth impedance unit 240 is grounded;

the first impedance unit 210, the second impedance unit 220, and the third impedance unit 230 all have resistance values, and the resistance values of the grounding module 200 can be controlled to be changed regularly by controlling the on/off of the first impedance unit 210, the second impedance unit 220, the third impedance unit 230, and the fourth impedance unit 240.

With continued reference to fig. 3, in a specific embodiment, the first impedance unit 210 is composed of only the first resistor R1, the second impedance unit 220 is composed of the second resistor R2 and the second resistor switch Q2, and the third impedance unit 230 is composed of the third resistor R3 and the third resistor switch Q3. The adjustable switch has the advantages that one resistor is normally used, the number of operation switches is reduced, the number of the adjustable switches is reduced, the investment is low, the adjustment is convenient, and the structure is simple. The combined size of the resistors can also be chosen differently.

With continued reference to fig. 3, in an embodiment, the resistance of the first resistor R1 is equal to the resistance of the second resistor R2 and is 2 times the resistance of the fourth impedance unit 240, the resistance of the third resistor R3 is zero, and the control module implements regular change of the total resistance by controlling the on/off states of the second resistor switch Q2 or the third resistor switch Q3 of the second impedance unit 220 or the third impedance unit 230.

The second resistive switch Q2 and the third resistive switch Q3 are circuit breakers. The resistance values of the first impedance unit 210, the second impedance unit 220, the third impedance unit 230, and the fourth impedance unit 240 may be determined according to the voltage of the system connected to the grounding module 200. Illustratively, the resistance values of the first impedance unit 210, the second impedance unit 220, and the third impedance unit 230 are 8 ohms, and 0 ohms, respectively, and the resistance value of the fourth impedance unit 240 is 4 ohms, and in other embodiments, the resistance values of the first impedance unit 210, the second impedance unit 220, and the third impedance unit 230 are 10 ohms, and 0 ohms, respectively, and the resistance value of the fourth impedance unit 240 is 5 ohms, respectively. Taking the above-mentioned 8 ohms, 0 ohms and 4 ohms of the fourth impedance unit 240 as an example, the second resistor switch Q2 and the third resistor switch Q3 are both turned off, and the ground module 200 has a 12 ohm resistance; furthermore, when the second resistor switch Q2 is in the closed position, the resistance of the grounding module 200 is 8 ohms; furthermore, when the third resistor switch Q3 of the third impedance unit 230 is also turned on, the resistance of the grounding module 200 is 4 ohms. The resistance value of the grounding module 200 can be changed regularly by controlling the on/off of the resistor switch Q, for example, the resistance value of the grounding module 200 can be decreased from 12 ohms to 8 ohms, then decreased from 4 ohms to 12 ohms. The grounding module 200 is provided with 3 branches and is adjusted by using two resistance switches, namely, one resistance is normally input, the number of operation switches is reduced, the number of adjustable switches is reduced, the investment is low, the adjustment is convenient, and the structure is simple. The combined size of the resistors can also be chosen differently.

With continued reference to fig. 3, in a particular embodiment, the first protection module 400 further includes a grounding transformer T2 and a first current collection unit 410, and the second protection module 500 further includes a second current collection unit 510;

one end of the grounding transformer T2 is electrically connected to the first switch unit L2, and the other end of the grounding transformer T2 is electrically connected to the first end of the first impedance unit 210, the second impedance unit 220, and the third impedance unit 230 after being connected in parallel;

one end of the first current collecting unit 410 is electrically connected to the second end of the fourth impedance unit 240, the other end of the first current collecting unit 410 is grounded, and the first current collecting unit 410 is used for collecting the current of the first protection module 400;

the second current collecting units 510 are disposed on the corresponding spaced lines.

The first current collection unit 410 and the second current collection unit 510 may be current transformers, the first current collection unit 410 is configured to collect zero sequence current of a line where the first protection module 400 is located, and the second current collection unit 510 is configured to collect zero sequence current of a line at an interval where the second protection module 500 is located.

With continued reference to fig. 3, in a specific embodiment, the operating system further includes a voltage acquisition module PT, and the voltage acquisition module PT is electrically connected to the control module 300 and the bus 100, respectively, for acquiring the zero sequence voltage of the operating system.

The voltage acquisition module PT can be a voltage transformer which can acquire the zero sequence voltage of the system.

According to the technical scheme of the embodiment, when the resistance value of the grounding resistor is controlled to decrease progressively according to a rule, the decreasing operation can be completed by controlling one switch when the resistance value decreases progressively each time, so that the control mode is simpler and more convenient.

The control method of the resistance grounding system specifically comprises the following steps:

the method comprises the following steps: the control module collects the position information of the first switch unit, the second switch unit and the section switch, and determines the operation mode of the system according to the position information; sending the operation mode to a first protection module, a second protection module and a control module of an adjacent operation system;

when the first switch unit is in the closed position, the second switch unit is in the closed position, and the section switch connected with any adjacent running system of the running system to which the control module belongs is in the separated position, determining that the running system is in an independent running mode;

and when the section switch of any adjacent operation system of the operation system to which the control module belongs is closed, determining that the operation system is in a parallel operation mode.

Step two: the control module generates a control signal according to the zero sequence voltage;

step three: when the zero sequence voltage is larger than a preset voltage threshold, the control module generates a resistance value change control signal;

and the grounding module controls the self resistance value to change according to a preset rule according to the resistance value change control signal.

Step four: when the second protection module is matched with the change rule of the resistance value of the grounding module according to the change rule of the zero sequence current of the second protection module, the second protection module controls the third switch unit to be switched off and generates a first action signal;

when the second protection module is not matched with the change rule of the resistance value of the grounding module according to the change rule of the zero sequence current of the second protection module, the second protection module controls the third switch unit not to act and generates a second action signal;

under the condition that the first protection module is matched with the change rule of the resistance value of the grounding module according to the change rule of the zero sequence current of the first protection module and the operation mode is an independent operation mode, when the action signal is a first action signal and the zero sequence current of the first protection module is greater than a first set current value, or the action signal is a second action signal or a third action signal, the first protection module controls the first switch unit and the second switch unit to be switched off;

the third action signal is a signal generated when the second protection module is matched with the change rule of the resistance of the grounding module according to the relation between the change rule of the zero sequence current of the second protection module and the change rule of the resistance of the grounding module and the third switch unit does not act;

under the conditions that the first protection module is matched with the change rule of the resistance value of the grounding module according to the change rule of the zero sequence current of the first protection module and the change rule of the resistance value of the grounding module, and the operation mode is a parallel operation mode, when the action signal is a second action signal, the section switch is switched off, and after a set time, the zero sequence current of the first protection module is smaller than a second set current value, and the first protection module controls the first switch unit and/or the second switch unit to be not operated;

and under the condition that the first protection module is matched with the change rule of the resistance value of the grounding module according to the change rule of the zero sequence current of the first protection module and the operation mode is the parallel operation mode, the first protection module controls the first switch unit and/or the second switch unit to be switched off when the action signal is the first action signal and the zero sequence current of the first protection module is greater than 50% of the first set current value or the action signal is the third action signal.

In the control method of the resistance grounding system in this embodiment, the second switch module generates a first action signal, a first action signal and a third action signal, and under the condition that the first protection module is matched with the change rule of the resistance of the grounding module according to the change rule of the zero sequence current of the first protection module and the change rule of the resistance of the grounding module, and the operation mode is an independent operation mode, when the action signal is the first action signal and the zero sequence current of the first protection module is greater than a first set current value, or the action signal is the second action signal or the third action signal, the first protection module controls the first switch unit and the second switch unit to be both switched off, so as to remove the fault. Under the conditions that the first protection module is matched with the change rule of the resistance value of the grounding module according to the change rule of the zero sequence current of the first protection module and the change rule of the resistance value of the grounding module, and the operation mode is a parallel operation mode, when the action signal is a second action signal, the section switch is switched off, and after a set time, the zero sequence current of the first protection module is smaller than a second set current value, and the first protection module controls the first switch unit and/or the second switch unit to be not operated; and under the condition that the first protection module is matched with the change rule of the resistance value of the grounding module according to the change rule of the zero sequence current of the first protection module and the operation mode is the parallel operation mode, when the action signal is the first action signal and the zero sequence current of the first protection module is greater than 50% of the first set current value or the action signal is the third action signal, the first protection module controls the first switch unit and/or the second switch unit to be switched off, so that the fault is removed. The control method of the resistance grounding system of the embodiment determines whether a fault occurs by using the relation of the change rule of the zero sequence current and the resistance value of the grounding module, and compared with the method of determining whether the fault occurs by simply depending on the magnitude relation of the zero sequence current and the set current setting value, the control method of the resistance grounding system can also remove the fault when the ground fault occurs and the zero sequence current is smaller than the set current setting value.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the utility model. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (5)

1. A resistance grounding system is characterized by comprising at least two operation systems and a section switch connected with the adjacent operation systems, wherein each operation system comprises a bus, a main transformer corresponding to the bus, a grounding module, a control module, a first protection module, at least one interval and a second protection module arranged at the interval; the first protection module comprises a first switch unit and a second switch unit, the grounding module is connected with the bus through the first switch unit, and the bus is connected with the main transformer through the second switch unit; the second protection module comprises a third switching unit, and the third switching unit is used for controlling the connection state of the grounding module and the corresponding resistor;

in any one of the operating systems, the control module is respectively connected with the first switch unit, the second switch unit and the section switch;

the control module is electrically connected with the grounding module, the grounding module comprises a parallel group and a fourth impedance unit, the parallel group is formed by connecting a first impedance unit, a second impedance unit and a third impedance unit in parallel, the first end of the parallel group is electrically connected with the first switch unit, the second end of the parallel group is electrically connected with the first end of the fourth impedance unit, and the second end of the fourth impedance unit is grounded; the first impedance unit is composed of only a first resistor, the second impedance unit is composed of a second resistor and a second resistor switch, and the third impedance unit is composed of a third resistor and a third resistor switch.

2. The resistance grounding system of claim 1, wherein the resistance value of the first resistor is equal to the resistance value of the second resistor and is 2 times of the resistance value of the fourth impedance unit, the resistance value of the third resistor is zero, and the control module controls the on/off state of the second resistor switch or the third resistor switch to realize regular change of the total resistance value.

3. The resistive grounding system of claim 1, wherein the second and third resistive switches are circuit breakers.

4. The resistive grounding system of claim 1, wherein the first protection module includes a grounding transformer and a first current collection unit, the second protection module further including a second current collection unit;

one end of the grounding transformer is electrically connected with the first switch unit, and the other end of the grounding transformer is electrically connected with the first end of the first impedance unit, the second impedance unit and the third impedance unit which are connected in parallel;

one end of the first current acquisition unit is electrically connected with the second end of the fourth impedance unit, the other end of the first current acquisition unit is grounded, and the first current acquisition unit is used for acquiring the current of the first protection module;

the second current collecting units are arranged on the corresponding spaced lines.

5. The resistive grounding system of claim 1, wherein the operating system further comprises a voltage acquisition module electrically connected to the control module and the bus, respectively, the voltage acquisition module configured to acquire a zero sequence voltage of the operating system.

Images