Grounding resistance monitoring system for power transformation equipment

Abstract

The utility model provides a power transformation equipment grounding resistance monitoring system which comprises a power supply unit, a control chip, a sampling circuit, a normally open relay, a normally closed relay, a monitoring control circuit and a grounding environment monitoring unit. The resistance value change of the grounding resistor of the power transformation equipment can be accurately monitored, so that an accurate data basis is provided for formulation of subsequent processing measures, stable operation of a power system is guaranteed, the influence of a test signal on the power transformation equipment can be effectively prevented in the monitoring process, the stability of the whole system is further improved, and the reliability of the system is improved. And the system is relatively simple in structure and high in reliability.

Description

Technical Field

[0001] The utility model relates to an electric power monitoring system, in particular to a grounding resistance monitoring system for transformer equipment. Background Art

[0002] There are various substation equipment in the power grid, such as transformers. These substation equipment need to be grounded during service. If the grounding is poor, serious consequences will occur. Take the transformer as an example: especially the main transformer. If the grounding is poor during normal operation, the impact is often small. Especially during the substation operation, if the grounding is poor, it will cause the current to be out of control, which is easy to cause arc discharge in the transformer, thereby burning the transformer, and there are serious safety hazards and the power quality of the power grid will be reduced. Therefore, these substation equipment need to be well grounded.

[0003] In the prior art, grounding monitoring of substation equipment is mainly fed back through the resistance of the grounding resistor. The resistance of the grounding resistor is generally at a set value. When there is poor grounding, the resistance of the grounding resistor increases. For example, soil moisture conditions, the contact area between the grounding resistor and the earth, and corrosion of the grounding resistor will cause the resistance of the grounding resistor to increase. The existing grounding resistance monitoring technology has the following defects: low monitoring accuracy, which cannot accurately reflect the resistance state of the grounding resistor. If the accuracy is to be improved, the overall structure of the monitoring system will be extremely complex, costly, and unstable. More importantly, generally speaking, a test signal will be injected into the grounding resistor during grounding resistance monitoring. If the test signal is not handled properly, it is easy to form a backflow into the substation equipment, which is easy to cause substation failure or even substation accidents.

[0004] Therefore, in order to solve the above technical problems, it is urgent to propose a new technical means. Utility Model Content

[0005] In view of this, the purpose of the utility model is to provide a grounding resistance monitoring system for substation equipment, which can accurately monitor the resistance changes of the grounding resistance of the substation equipment, thereby providing accurate data basis for the formulation of subsequent processing measures, ensuring the stable operation of the power system, and effectively preventing the influence of test signals on the substation equipment during the monitoring process, further improving the stability of the entire system, and the system structure is relatively simple and has high reliability.

[0006] The utility model provides a grounding resistance monitoring system for substation equipment, comprising a power supply unit, a control chip, a sampling circuit, a normally open relay, a normally closed relay, a monitoring control circuit and a grounding environment monitoring unit;

[0007] One end of the normally closed switch K1 of the normally closed relay is connected to the ground through the grounding resistor RL, and the other end of the normally closed switch K1 is connected to the grounding point of the transformer equipment, the input end of the excitation coil J1 of the normally closed relay is connected to the first output end of the monitoring control circuit, and the output end of the excitation coil J1 of the normally closed relay is grounded, one end of the normally open switch K2 of the normally open relay is connected to the common connection point between the grounding resistor RL and the normally closed switch K1, the other end of the normally open switch K2 is connected to the input end of the sampling circuit, the input end of the excitation coil J2 of the normally open relay is connected to the second output end of the monitoring control circuit, and the output end of the excitation coil J2 of the normally open relay is grounded; the test signal output end of the monitoring control circuit is connected to the common connection point between the grounding resistor RL and the normally closed switch K1, the control input end of the monitoring control circuit is connected to the control chip, the power input end of the monitoring control circuit is connected to the output end of the power supply unit, the output end of the sampling circuit and the grounding environment monitoring unit is connected to the input end of the control chip, and the control chip is communicatively connected with the monitoring host through the wireless communication module.

[0008] Further, the monitoring control circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a diode D1, an NMOS tube Q1, an NMOS tube Q2, and an NMOS tube Q3;

[0009] The drain of the NMOS tube Q3 is connected to the power supply unit as the power input end of the monitoring control circuit, the gate of the NMOS tube Q3 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the control chip as the control input end of the monitoring control circuit, the source of the NMOS tube Q3 is connected to the drain of the NMOS tube Q1 through the resistor R4, the source of the NMOS tube Q3 is connected to the drain of the NMOS tube Q2 through the resistor R6, the source of the NMOS tube Q1 is connected to one end of the resistor R2, and the other end of the resistor R2 is used as the first output end of the monitoring control circuit, the source of the NMOS tube Q1 is connected to one end of the resistor R1, and the other end of the resistor R1 is used as the second output end of the monitoring control circuit, and the gate of the NMOS tube Q1 is connected to the source of the NMOS tube Q3 through the resistor R3;

[0010] The gate of the NMOS tube Q2 is connected to the source of the NMOS tube Q3 through the resistor R5, the gate of the NMOS tube Q2 is grounded through the capacitor C2, the source of the NMOS tube Q2 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to one end of the resistor R8, and the other end of the resistor R8 serves as the test signal output end of the monitoring control circuit.

[0011] Further, the sampling circuit includes a resistor R9, a capacitor C1 and an A / D sampling chip;

[0012] One end of the resistor R9 serves as the input end of the sampling circuit, and the other end of the resistor R9 is grounded through the capacitor C1. The common connection point between the resistor R9 and the capacitor C1 is connected to the input end of the A / D sampling chip, and the output end of the A / D sampling circuit is connected to the control chip.

[0013] Furthermore, the ground environment monitoring unit includes a soil moisture sensor and a soil pH value sensor, and the output ends of the soil moisture sensor and the soil pH value sensor are both connected to the input end of the control chip.

[0014] Furthermore, the wireless communication module is a 5G communication module or a 2.4G power wireless private network module.

[0015] Furthermore, the monitoring host is also provided with a touch display and an alarm, and both the touch display and the alarm are connected to the monitoring host.

[0016] The beneficial effects of the utility model are as follows: through the utility model, the resistance change of the grounding resistance of the substation equipment can be accurately monitored, thereby providing an accurate data basis for the formulation of subsequent processing measures, ensuring the stable operation of the power system, and in the monitoring process, it can effectively prevent the influence of the test signal on the substation equipment, further improving the stability of the entire system, and the system structure is relatively simple and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0018] Figure 1 It is a structural schematic diagram of the utility model.

[0019] Figure 2 This is a schematic diagram of the monitoring and control circuit of the utility model. DETAILED DESCRIPTION

[0020] The utility model is further described in detail below:

[0021] The utility model provides a grounding resistance monitoring system for substation equipment, comprising a power supply unit, a control chip, a sampling circuit, a normally open relay, a normally closed relay, a monitoring control circuit and a grounding environment monitoring unit;

[0022] One end of the normally closed switch K1 of the normally closed relay is connected to the ground through the grounding resistor RL, and the other end of the normally closed switch K1 is connected to the grounding point of the transformer equipment, the input end of the excitation coil J1 of the normally closed relay is connected to the first output end of the monitoring control circuit, and the output end of the excitation coil J1 of the normally closed relay is grounded, one end of the normally open switch K2 of the normally open relay is connected to the common connection point between the grounding resistor RL and the normally closed switch K1, the other end of the normally open switch K2 is connected to the input end of the sampling circuit, the input end of the excitation coil J2 of the normally open relay is connected to the second output end of the monitoring control circuit, and the output end of the excitation coil J2 of the normally open relay is grounded; the test signal output end of the monitoring control circuit is connected to the common connection point between the grounding resistor RL and the normally closed switch K1, the control input end of the monitoring control circuit is connected to the control chip, the power input end of the monitoring control circuit is connected to the output end of the power supply unit, the output end of the sampling circuit and the grounding environment monitoring unit is connected to the input end of the control chip, and the control chip is communicatively connected with the monitoring host through the wireless communication module. Among them, the power supply unit adopts the existing method, for example: the power supply VCC is obtained after the voltage stabilization treatment by the battery, and the online power supply method can also be adopted, that is, the current transformer is used to inductively obtain power on the transmission line, and then the full-bridge rectifier circuit is used for rectification, and then the filter circuit is used for filtering, and finally the existing voltage stabilization circuit (the model of the voltage stabilization circuit is selected according to actual needs, for example: LM7812, LM2596, AMS1117 series voltage stabilization circuit, the corresponding model is selected according to the actual required voltage) is used for voltage stabilization and then power supply. Of course, the power supply method of the control chip is the same as the above; the control chip adopts the existing single-chip microcomputer, such as the STM32 series single-chip microcomputer, these single-chip microcomputers have corresponding peripheral circuits, which belong to the existing technology and are not described here; through the above structure, the resistance change of the grounding resistance of the substation equipment can be accurately monitored, thereby providing accurate data basis for the formulation of subsequent processing measures, ensuring the stable operation of the power system, and in the monitoring process, the test signal can be effectively prevented from affecting the substation equipment, further improving the stability of the entire system, and the system structure is relatively simple and the reliability is high.

[0023] Among them, Figure 1 In the figure, the dotted arrows indicate the signal flow direction, and the real arrows indicate the current flow direction.

[0024] In this embodiment, the monitoring control circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a diode D1, an NMOS tube Q1, an NMOS tube Q2, and an NMOS tube Q3;

[0025] The drain of the NMOS tube Q3 is connected to the power supply unit as the power input end of the monitoring control circuit, the gate of the NMOS tube Q3 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the control chip as the control input end of the monitoring control circuit, the source of the NMOS tube Q3 is connected to the drain of the NMOS tube Q1 through the resistor R4, the source of the NMOS tube Q3 is connected to the drain of the NMOS tube Q2 through the resistor R6, the source of the NMOS tube Q1 is connected to one end of the resistor R2, and the other end of the resistor R2 is used as the first output end of the monitoring control circuit, the source of the NMOS tube Q1 is connected to one end of the resistor R1, and the other end of the resistor R1 is used as the second output end of the monitoring control circuit, and the gate of the NMOS tube Q1 is connected to the source of the NMOS tube Q3 through the resistor R3;

[0026] The gate of NMOS tube Q2 is connected to the source of NMOS tube Q3 through resistor R5, the gate of NMOS tube Q2 is grounded through capacitor C2, the source of NMOS tube Q2 is connected to the positive electrode of diode D1, the negative electrode of diode D1 is connected to one end of resistor R8, and the other end of resistor R8 is used as the test signal output end of the monitoring control circuit, wherein the control chip outputs a high level signal to NMOS tube Q3 according to a set period, and the period is set according to actual conditions, for example, a high level signal is output once every 24 hours, and each high level signal is maintained for 30 seconds. At this time, NMOS tube Q3 is OS tube Q3 is turned on, and the DC power provided by the power supply VCC flows to the gate and drain of NMOS tubes Q1 and Q2 respectively. Due to the existence of capacitor C2, NMOS tube Q1 is turned on earlier than NMOS tube Q2. That is to say, after NMOS tube Q1 is turned on, the excitation coil J1 of the normally closed relay is energized, thereby disconnecting the normally closed switch K1. At the same time, the excitation coil J2 of the normally open relay is energized, and the normally open switch K2 is closed. Then, when the voltage of capacitor C2 reaches the conduction threshold of NMOS tube Q2, NMOS tube Q2 is turned on, thereby injecting a test signal into the grounding resistance. At this time, since the normally closed switch K1 is disconnected, the test signal is prevented from flowing back into the substation, thereby ensuring the safety of the substation. Moreover, the resistor R8 and the grounding resistor RL form a voltage divider circuit, which is filtered by the resistor R9 and the capacitor C1 and input into the A / D sampling chip for sampling, and then output to the control chip and the control chip calculates the voltage divider value of the grounding resistor at this time, and then calculates the corresponding grounding resistor value. The larger the resistance value, the larger the voltage divider value. The control chip uploads the current grounding resistor value to the monitoring host, and the monitoring host calculates the grounding resistor value according to the grounding resistor value. Corresponding warning is carried out. After the test is completed, the control chip outputs a low level to the NMOS tube Q3, and the NMOS tube Q3 is turned off, so that the NMOS tubes Q1 and Q2 are both turned off, the normally closed switch K1 is closed again, and the normally open switch K2 is opened again, so as not to affect the grounding of the substation equipment and the current during grounding on the sampling chip and the control chip. It should be noted that the timing of the control chip outputting a high level should be the window when the substation equipment will not be subjected to substation operation during daily operation. In these windows, even if the grounding is temporarily disconnected, it will not cause any impact on the substation equipment.

[0027] In this embodiment, the sampling circuit includes a resistor R9, a capacitor C1 and an A / D sampling chip;

[0028] One end of the resistor R9 serves as the input end of the sampling circuit, and the other end of the resistor R9 is grounded through the capacitor C1. The common connection point between the resistor R9 and the capacitor C1 is connected to the input end of the A / D sampling chip, and the output end of the A / D sampling circuit is connected to the control chip. The A / D sampling chip adopts the existing analog-to-digital conversion chip, which will not be described in detail here. The resistor R9 and the capacitor C1 form an RC filter circuit, and the resistor R9 has a certain current limiting effect.

[0029] In this embodiment, the grounding environment monitoring unit includes a soil moisture sensor and a soil pH sensor, and the output ends of the soil moisture sensor and the soil pH sensor are connected to the input end of the control chip, wherein the soil moisture sensor and the pH sensor are used to monitor the soil environment. For example, if the soil moisture is too low, even if the grounding resistance is normal, the resistance of the grounding resistance will increase, and the pH environment of the soil will corrode the grounding resistance, thereby increasing the grounding resistance. Therefore, according to the current soil environment parameters and resistance conditions, a basic judgment can be made on the resistance change of the grounding resistance. For example: the current resistance increases, and only the soil moisture decreases in the soil environment parameters, then it can be concluded that the current increase in the resistance of the grounding resistance is caused by insufficient soil moisture. For example: if the soil environment parameters are all normal, that is, the soil environment has little effect on the resistance of the grounding resistance, then the current increase in resistance may be due to loose connection of the grounding resistance, deformation of the grounding wire, and the like.

[0030] In this embodiment, the wireless communication module is a 5G communication module or a 2.4G power wireless private network module. The use of this structure is conducive to data transmission, has high efficiency, and does not require additional communication line layout.

[0031] In this embodiment, the monitoring host is also provided with a touch display and an alarm, both of which are connected to the monitoring host, which is conducive to timely warning and timely display of the current resistance change status, and the alarm adopts an existing sound and light alarm.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A grounding resistance monitoring system for substation equipment, characterized in that: It includes a power supply unit, a control chip, a sampling circuit, a normally open relay, a normally closed relay, a monitoring control circuit and a grounding environment monitoring unit; One end of the normally closed switch K1 of the normally closed relay is connected to the ground through the grounding resistor RL, and the other end of the normally closed switch K1 is connected to the grounding point of the transformer equipment, the input end of the excitation coil J1 of the normally closed relay is connected to the first output end of the monitoring control circuit, and the output end of the excitation coil J1 of the normally closed relay is grounded, one end of the normally open switch K2 of the normally open relay is connected to the common connection point between the grounding resistor RL and the normally closed switch K1, the other end of the normally open switch K2 is connected to the input end of the sampling circuit, the input end of the excitation coil J2 of the normally open relay is connected to the second output end of the monitoring control circuit, and the output end of the excitation coil J2 of the normally open relay is grounded; the test signal output end of the monitoring control circuit is connected to the common connection point between the grounding resistor RL and the normally closed switch K1, the control input end of the monitoring control circuit is connected to the control chip, the power input end of the monitoring control circuit is connected to the output end of the power supply unit, the output end of the sampling circuit and the grounding environment monitoring unit is connected to the input end of the control chip, and the control chip is communicatively connected with the monitoring host through the wireless communication module.

2. The grounding resistance monitoring system for substation equipment according to claim 1 is characterized in that: The monitoring control circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a diode D1, an NMOS tube Q1, an NMOS tube Q2, and an NMOS tube Q3; The drain of the NMOS tube Q3 is connected to the power supply unit as the power input end of the monitoring control circuit, the gate of the NMOS tube Q3 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the control chip as the control input end of the monitoring control circuit, the source of the NMOS tube Q3 is connected to the drain of the NMOS tube Q1 through the resistor R4, the source of the NMOS tube Q3 is connected to the drain of the NMOS tube Q2 through the resistor R6, the source of the NMOS tube Q1 is connected to one end of the resistor R2, and the other end of the resistor R2 is used as the first output end of the monitoring control circuit, the source of the NMOS tube Q1 is connected to one end of the resistor R1, and the other end of the resistor R1 is used as the second output end of the monitoring control circuit, and the gate of the NMOS tube Q1 is connected to the source of the NMOS tube Q3 through the resistor R3; The gate of the NMOS tube Q2 is connected to the source of the NMOS tube Q3 through the resistor R5, the gate of the NMOS tube Q2 is grounded through the capacitor C2, the source of the NMOS tube Q2 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to one end of the resistor R8, and the other end of the resistor R8 serves as the test signal output end of the monitoring control circuit.

3. The grounding resistance monitoring system for substation equipment according to claim 1 is characterized in that: The sampling circuit includes a resistor R9, a capacitor C1 and an A / D sampling chip; One end of the resistor R9 serves as the input end of the sampling circuit, and the other end of the resistor R9 is grounded through the capacitor C1. The common connection point between the resistor R9 and the capacitor C1 is connected to the input end of the A / D sampling chip, and the output end of the A / D sampling circuit is connected to the control chip.

4. The grounding resistance monitoring system for substation equipment according to claim 1 is characterized in that: The ground environment monitoring unit includes a soil moisture sensor and a soil pH value sensor, and the output ends of the soil moisture sensor and the soil pH value sensor are both connected to the input end of the control chip.

5. The grounding resistance monitoring system for substation equipment according to claim 1 is characterized in that: The wireless communication module is a 5G communication module or a 2.4G power wireless private network module.

6. The grounding resistance monitoring system for substation equipment according to claim 1 is characterized in that: The monitoring host is also provided with a touch display and an alarm, and both the touch display and the alarm are connected to the monitoring host.

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