CN113391124A - Method, device and system for monitoring insulation level of medium-voltage power system - Google Patents
Method, device and system for monitoring insulation level of medium-voltage power system Download PDFInfo
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- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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Abstract
The invention relates to a method, a device and a system for monitoring the insulation level of a medium-voltage power system, wherein the method comprises the steps of firstly, arranging a plurality of insulation level monitoring devices, injection resistors, isolation capacitors and Hall current sensors on a plurality of buses and a plurality of feeders of the medium-voltage power system by adopting a direct-current voltage injection method; then calculating the direct current voltage value injected by each insulation level monitoring device according to a gradient voltage method; then, performing double-state operation on all insulation level monitoring devices in the medium-voltage power system according to a round sequence control method; and finally, the direct-current insulation resistance of the medium-voltage power system to be monitored is obtained according to a system insulation resistance calculation method, so that the insulation state of the medium-voltage power system is obtained, the insulation state is more visual, communication among a plurality of insulation level monitoring devices is not needed, and the sequential monitoring can be realized only by monitoring the direct-current voltage according to respective numbers, so that distributed control is realized, the arrangement difficulty is greatly reduced, and the wiring complexity is reduced.
Description
Technical Field
The invention belongs to the technical field of power supply protection of power systems, and particularly relates to a method, a device and a system for monitoring the insulation level of a medium-voltage power system.
Background
At present, a medium-voltage power system is an important ring in a power supply and distribution network of a power system, the voltage class of the medium-voltage power system is usually 3kV, 6kV, 10kV, 35kV and 66kV, and the medium-voltage power system is mainly characterized in that the neutral point of the system under the voltage class often exists: the mode of ungrounded operation, small-resistance grounded operation and arc-extinguishing coil operation. Various neutral point operation modes exist in urban power distribution networks, rural power distribution networks, railway power supply and distribution systems and industrial and mining enterprise power distribution networks. Due to the factors of diversified operation modes of neutral points, complex network architecture, large amount of energy and the like under the voltage level, the insulation level monitoring in the power system is difficult to continuously observe on line.
In actual operation of the power system, potential operation hazards can be caused after the insulation level is reduced, the leakage current of the system is increased, and the operation reliability of the system is reduced. Meanwhile, when the equipment is switched from cold standby to hot standby or is not operated for a long time and is put into operation again, the insulation state of the equipment needs to be tested, a large amount of manpower and material resources are consumed, and a large amount of waiting production time is occupied.
However, currently, common monitoring means, such as partial discharge measurement, cannot accurately measure the insulation resistance of the equipment, and is obviously affected by air humidity, and in addition, partial discharge generally only measures a single equipment and cannot perform insulation monitoring on the whole power network or system; although the leakage current measurement can monitor the network system, the measurement index is obviously affected by the weather, and the current insulation state cannot be accurately represented. Meanwhile, according to the definition of the insulation resistance, the real insulation state of the equipment or the system is really reflected only by applying direct current voltage to the equipment or the system and calculating the resistance to be the insulation resistance of the equipment or the system. The existing partial discharge monitoring and leakage current monitoring cannot obtain the true insulation resistance of the equipment or the system.
It can be seen that there are a number of problems with the prior art.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides an insulation level monitoring method, an insulation level monitoring device and an insulation level monitoring system, wherein the insulation level monitoring method can obtain the real direct current insulation resistance of a medium-voltage power system, the insulation state is more visual, and the arrangement difficulty is low.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a method for monitoring the insulation level of a medium-voltage power system, which comprises the following steps:
arranging a plurality of insulation level monitoring devices, injection resistors, isolation capacitors and Hall current sensors on a plurality of buses and a plurality of feeders of a medium-voltage power system by adopting a direct-current voltage injection method;
calculating a direct current voltage value injected by each insulation level monitoring device according to a gradient voltage method;
performing double-state operation on all insulation level monitoring devices in the medium-voltage power system according to a round sequence control method;
and obtaining the direct-current insulation resistance of the medium-voltage power system to be monitored according to the system insulation resistance calculation method, thereby obtaining the insulation state of the medium-voltage power system.
Further, the "calculating the dc voltage value injected by each insulation level monitoring device according to a gradient voltage method" specifically includes:
s101, sequentially numbering 1 and 2 … … n for each insulation level monitoring device in a medium-voltage power system;
s102, judging the numerical range of n, and when n is less than or equal to 11, outputting the direct-current voltage injected by each insulation level monitoring device according to the numerical value calculated in S103; when n is larger than or equal to 12, outputting the direct-current voltage injected by each insulation level monitoring device according to the numerical value calculated in S104;
s103, when n is an even number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 +/-50 k, k is 0, 1, … … and n/2; when n is an odd number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 ± 50k, k ═ 0, 1, … …, (n-1)/2;
s104, when n is an even number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 +/-500 k/n, wherein k is 0, 1, … … and n/2; when n is an odd number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 ± 500k/(n-1), k ═ 0, 1, … …, (n-1)/2.
Further, the dual-state operation method comprises a direct-current voltage injection and insulation level calculation state and a non-direct-current voltage injection and insulation level calculation state; wherein the content of the first and second substances,
the direct current voltage injection and insulation level calculation state is that the direct current voltage injected by the insulation level monitoring device calculated according to the gradient voltage method is divided by the output current of the insulation level monitoring device, and then the injection resistance is subtracted to obtain the system insulation resistance of the monitoring point;
the non-direct-current voltage injection and insulation level calculation state is that after the current insulation level monitoring device stops injecting direct-current voltage, direct-current voltage injected by other insulation level monitoring devices is collected, the collected direct-current voltage is divided by a Hall current sensor at the installation point position of the current insulation level monitoring device to obtain Hall direct current, and load side insulation resistance under the non-injected direct-current voltage is obtained.
Further, the round control method includes:
s201, starting the insulation level monitoring devices with the numbers of 1, working in a direct-current voltage injection and insulation level calculation state t1 time, and working in a non-direct-current voltage injection and insulation level calculation state by the insulation level monitoring devices with other numbers;
s202, stopping direct-current voltage injection and insulation level calculation for n-1 t1 time after the insulation level monitoring device with the number of 1 exceeds t1 time;
s203, the insulation level monitoring devices with other numbers monitor the loss of the direct-current voltage of the system, the insulation level monitoring device with the number 2 works in a direct-current voltage injection and insulation level calculation state t1 time, and the insulation level monitoring devices with other numbers work in a non-direct-current voltage injection and insulation level calculation state;
s204, completing the rotation of the direct-current voltage injection and insulation level calculation states and the non-direct-current voltage injection and insulation level calculation states of the n insulation level monitoring devices according to the processes from S202 to S203 in sequence;
and S205, after the insulation level monitoring device with the number of n finishes the direct-current voltage injection and the insulation level calculation state t1, the step S201 is re-entered to realize circulation.
Further, the time t1 of the dc voltage injection and insulation level calculation state is not less than 60 s.
Further, the "obtaining the dc insulation resistance of the medium voltage power system to be monitored according to the system insulation resistance calculation method, thereby obtaining the insulation state of the medium voltage power system" includes:
s301, when the difference between the system insulation resistance obtained by calculation of each insulation level monitoring device and the average value of all the system insulation resistances except the current monitoring device is not more than 50%, the insulation resistance of the current insulation level monitoring device is determined to be the effective system insulation resistance;
s302, taking the average value of all effective system insulation resistances as the system insulation resistance of the power system to be monitored;
and S303, calculating the average value of the insulation resistance values of the load side under the non-injection direct-current voltage obtained in the round sequence control, wherein the feeder line where the insulation level monitoring device with the minimum value is located is the feeder line with the weakest system insulation level.
Further, the "arranging a plurality of insulation level monitoring devices, injection resistors, isolation capacitors, and hall current sensors on a plurality of buses and a plurality of feeders of a medium voltage power system by using a direct current voltage injection method" specifically includes: the insulation level monitoring device comprises a medium-voltage power system, wherein an insulation level monitoring device, three injection resistors and a blocking capacitor are uniformly arranged at different positions of a plurality of buses and a plurality of feeders of the medium-voltage power system, one ends of the three injection resistors are sequentially connected with A, B, C three-phase medium-voltage buses or feeders of the medium-voltage power system, the other ends of the three injection resistors are connected in a star connection mode, star midpoints of the three injection resistors are connected with the insulation level monitoring device, all high-voltage side connection places in the medium-voltage power system are grounded through the isolation capacitor, Hall current sensors are arranged near the insulation level monitoring device, and A, B, C three-phase medium-voltage buses or feeders penetrate through the Hall current sensors in the direction from a bus power supply to a load side.
The invention also provides a device for monitoring the insulation level of the medium-voltage power system, which comprises an analog quantity detection module, a direct-current voltage generation module, a core control module, a communication module and a human-computer interface; the analog quantity monitoring module is used for monitoring analog quantities such as Hall current, direct current voltage and the like, the direct current voltage generating module is a direct current power supply and is used for being injected into an insulation level monitoring system of a medium-voltage power system, the core control module is a controller, a gradient voltage method module, a wheel sequence control method module, a two-state operation module and a system insulation resistance calculation method module are embedded into the core control module, the communication module is used for communication, and the human-computer interface is used for data display.
The invention also provides a system for monitoring the insulation level of the medium-voltage power system, which consists of a plurality of insulation level monitoring devices, an injection resistor, an isolation capacitor and a Hall current sensor, wherein the monitoring process is the method for monitoring the insulation level of the medium-voltage power system.
The invention has the beneficial effects that:
through the technical scheme, the invention can carry out overall insulation monitoring on the power system with the single bus and the multiple feeders, and has the following advantages:
1. by the method, a plurality of insulation level monitoring devices do not need to communicate with each other, and the sequential monitoring can be realized only by monitoring the direct-current voltage according to respective numbers, so that distributed control is realized, the arrangement difficulty is greatly reduced, and the wiring complexity is reduced.
2. The monitoring principle of the invention is simple, the real direct current insulation resistance is obtained by calculation, and the insulation state is more visual.
Drawings
FIG. 1 is a flow chart of an embodiment of a method of monitoring insulation level in a medium voltage power system according to the present invention;
fig. 2 is a schematic partial structural view of an embodiment of an insulation level monitoring system for a medium voltage power system according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, a method for monitoring insulation level of a medium voltage power system according to an embodiment of the present invention includes the following steps:
s1, arranging a plurality of insulation level monitoring devices, injection resistors, isolation capacitors and Hall current sensors on a plurality of buses and a plurality of feeders of a medium-voltage power system by adopting a direct-current voltage injection method; the method specifically comprises the following steps: referring to fig. 2, the insulation level monitoring system of the medium voltage power system according to the present invention comprises a plurality of insulation level monitoring devices, injection resistors, isolation capacitors, and hall current sensors (not shown in the figure), wherein when in use, one insulation level monitoring device, three injection resistors (high voltage resistors), and a blocking capacitor are disposed at different positions of a plurality of buses and a plurality of feeders of the medium voltage power system, one end of each of the three injection resistors is sequentially connected to A, B, C three-phase medium voltage buses or feeders of the medium voltage power system, the other ends of the three injection resistors are connected in a star connection manner, the star midpoint of each of the three injection resistors is connected to the insulation level monitoring device, all high voltage side connection points in the medium voltage power system are grounded through the isolation capacitors, the hall current sensors are disposed near each of the insulation level monitoring devices, and A, B, C three-phase medium voltage buses or feeders pass through the hall current sensors, the direction is from the bus power supply to the load side; the insulation level monitoring device comprises an analog quantity detection module, a direct current voltage generation module, a core control module, a communication module and a human-computer interface; the analog quantity monitoring module is used for monitoring analog quantities such as Hall current, direct current voltage and the like, the direct current voltage generating module is a direct current power supply and is used for being injected into an insulation level monitoring system of a medium-voltage power system, the core control module is a controller, a gradient voltage method module, a wheel sequence control method module, a two-state operation module and a system insulation resistance calculation method module are embedded into the core control module, the communication module is used for communication, and the human-computer interface is used for data display.
S2, calculating a direct-current voltage value injected by each insulation level monitoring device according to a gradient voltage method; the method specifically comprises the following steps:
s2-1, numbering 1 and 2 … … n for each insulation level monitoring device in the medium-voltage power system in sequence;
s2-2, judging the numerical range of n, and when n is less than or equal to 11, outputting the direct current voltage injected by each insulation level monitoring device according to the numerical value calculated in the step S2-3; when n is larger than or equal to 12, outputting the direct current voltage injected by each insulation level monitoring device according to the numerical value calculated in the step S2-4;
s2-3, when n is even number, the DC voltage output by each insulation level monitoring device is as follows: 1500 +/-50 k, k is 0, 1, … … and n/2; when n is an odd number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 ± 50k, k ═ 0, 1, … …, (n-1)/2;
s2-4, when n is even number, the DC voltage output by each insulation level monitoring device is as follows: 1500 +/-500 k/n, wherein k is 0, 1, … … and n/2; when n is an odd number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 ± 500k/(n-1), k ═ 0, 1, … …, (n-1)/2.
S3, performing double-state operation on all insulation level monitoring devices in the medium-voltage power system according to a round sequence control method; the double-state operation method comprises a direct-current voltage injection and insulation level calculation state and a non-direct-current voltage injection and insulation level calculation state; wherein the content of the first and second substances,
the round order control method comprises the following steps:
s3-1, starting the insulation level monitoring device with the number of 1, and working in a direct current voltage injection and insulation level calculation state for t1 time, wherein the insulation level monitoring devices with other numbers work in a non-direct current voltage injection and insulation level calculation state;
s3-2, after the insulation level monitoring device with the number of 1 exceeds t1 time, stopping direct current voltage injection and the insulation level calculation state for n-1 t1 time, wherein n represents the number of the insulation level monitoring devices in the medium-voltage power system, and n x t1 is just that the whole system completes one injection;
s3-3, if the insulation level monitoring devices with other numbers monitor the loss of the direct current voltage of the system, the insulation level monitoring device with the number 2 works in the direct current voltage injection and insulation level calculation state t1 time, and the insulation level monitoring devices with other numbers work in the non-direct current voltage injection and insulation level calculation state;
s3-4, completing the rotation of the direct current voltage injection and the insulation level calculation state and the non-direct current voltage injection and the insulation level calculation state of the n insulation level monitoring devices according to the processes of the steps S3-2 to S3-3;
s3-5, when the insulation level monitoring device with the number n finishes the direct current voltage injection and the insulation level calculation state for t1 time, the steps S3-1 to S3-5 are executed again to realize the circulation.
Furthermore, the time t1 of the dc voltage injection and the insulation level calculation state in the round-robin control method is preferably not less than 60s, which effectively ensures the monitoring accuracy, because if the time t1 is less than 60s, on one hand, the round-robin is too frequent, and on the other hand, the accuracy is affected by too short time due to changes in weather, humidity, etc.
The direct current voltage injection and insulation level calculation state is that the direct current voltage injected by the insulation level monitoring device calculated according to the gradient voltage method is divided by the output current of the insulation level monitoring device, and then the injection resistance is subtracted to obtain the system insulation resistance of the monitoring point; the method specifically comprises the following steps:
s3-6: each insulation level monitoring device obtains a direct current voltage value required to be injected according to a gradient voltage injection method;
s3-7: and dividing the self injection voltage of the insulation level monitoring device by the output current to calculate and subtract the injection resistance to obtain the system insulation resistance of the monitoring point.
The non-direct-current voltage injection and insulation level calculation state is that after the current insulation level monitoring device stops injecting direct-current voltage, direct-current voltage injected by other insulation level monitoring devices is collected, the collected direct-current voltage is divided by a Hall current sensor at the installation point position of the current insulation level monitoring device to obtain Hall direct current, and load side insulation resistance under the non-injected direct-current voltage is obtained; the method specifically comprises the following steps:
s3-8: stopping injecting the direct current voltage, and collecting port direct current voltage of the insulation level monitoring device (the direct current voltage is not output by the insulation level monitoring device at the current position, but is output by the insulation level monitoring devices at other positions);
s3-9: and dividing the port direct-current voltage by the Hall direct current at the mounting point position to obtain the load side insulation resistance under the non-injected direct-current voltage.
S4, obtaining the direct-current insulation resistance of the medium-voltage power system to be monitored according to a system insulation resistance calculation method, so as to obtain the insulation state of the medium-voltage power system; the method specifically comprises the following steps:
s4-1, when the difference between the system insulation resistance obtained by calculation of each insulation level monitoring device and the average value of all the system insulation resistances except the current monitoring device is not more than 50%, the insulation resistance of the current insulation level monitoring device is determined to be the effective system insulation resistance;
s4-2, taking the average value of all effective system insulation resistances as the system insulation resistance of the power system to be monitored;
and S4-3, calculating the average value of the load side insulation resistance values under the non-injection direct-current voltage obtained in the sequence control, wherein the feeder line where the insulation level monitoring device with the minimum value is located is the feeder line with the weakest system insulation level.
When the medium-voltage power system insulation level monitoring system is used for monitoring, the medium-voltage power system insulation level monitoring method is adopted, so that the power system with a single bus and multiple feeders can be subjected to overall insulation monitoring, communication among multiple insulation level monitoring devices is not needed, and sequential monitoring can be realized only by monitoring direct-current voltage according to respective numbers, so that distributed control is realized, the arrangement difficulty and wiring complexity are greatly reduced, the monitoring principle is simple, the real direct-current insulation resistance is obtained through calculation, and the insulation state is more visual.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (9)
1. A method of monitoring insulation level in a medium voltage power system, comprising:
arranging a plurality of insulation level monitoring devices, injection resistors, isolation capacitors and Hall current sensors on a plurality of buses and a plurality of feeders of a medium-voltage power system by adopting a direct-current voltage injection method;
calculating a direct current voltage value injected by each insulation level monitoring device according to a gradient voltage method;
performing double-state operation on all insulation level monitoring devices in the medium-voltage power system according to a round sequence control method;
and obtaining the direct-current insulation resistance of the medium-voltage power system to be monitored according to the system insulation resistance calculation method, thereby obtaining the insulation state of the medium-voltage power system.
2. The method according to claim 1, wherein the step of calculating the dc voltage value injected by each insulation level monitoring device according to a gradient voltage method includes:
s101, sequentially numbering 1 and 2 … … n for each insulation level monitoring device in a medium-voltage power system;
s102, judging the numerical range of n, and when n is less than or equal to 11, outputting the direct-current voltage injected by each insulation level monitoring device according to the numerical value calculated in S103; when n is larger than or equal to 12, outputting the direct-current voltage injected by each insulation level monitoring device according to the numerical value calculated in S104;
s103, when n is an even number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 +/-50 k, k is 0, 1, … … and n/2; when n is an odd number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 ± 50k, k ═ 0, 1, … …, (n-1)/2;
s104, when n is an even number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 +/-500 k/n, wherein k is 0, 1, … … and n/2; when n is an odd number, the direct-current voltage output by each insulation level monitoring device is as follows in sequence: 1500 ± 500k/(n-1), k ═ 0, 1, … …, (n-1)/2.
3. The method of claim 2, wherein the two-state operation method comprises a dc voltage injection and insulation level calculation state and a non-dc voltage injection and insulation level calculation state; wherein the content of the first and second substances,
the direct current voltage injection and insulation level calculation state is that the direct current voltage injected by the insulation level monitoring device calculated according to the gradient voltage method is divided by the output current of the insulation level monitoring device, and then the injection resistance is subtracted to obtain the system insulation resistance of the monitoring point;
the non-direct-current voltage injection and insulation level calculation state is that after the current insulation level monitoring device stops injecting direct-current voltage, direct-current voltage injected by other insulation level monitoring devices is collected, the collected direct-current voltage is divided by a Hall current sensor at the installation point position of the current insulation level monitoring device to obtain Hall direct current, and load side insulation resistance under the non-injected direct-current voltage is obtained.
4. The method according to claim 3, wherein the round-robin control method comprises:
s201, starting the insulation level monitoring devices with the numbers of 1, working in a direct-current voltage injection and insulation level calculation state t1 time, and working in a non-direct-current voltage injection and insulation level calculation state by the insulation level monitoring devices with other numbers;
s202, stopping direct-current voltage injection and insulation level calculation for n-1 t1 time after the insulation level monitoring device with the number of 1 exceeds t1 time;
s203, the insulation level monitoring devices with other numbers monitor the loss of the direct-current voltage of the system, the insulation level monitoring device with the number 2 works in a direct-current voltage injection and insulation level calculation state t1 time, and the insulation level monitoring devices with other numbers work in a non-direct-current voltage injection and insulation level calculation state;
s204, completing the rotation of the direct-current voltage injection and insulation level calculation states and the non-direct-current voltage injection and insulation level calculation states of the n insulation level monitoring devices according to the processes from S202 to S203 in sequence;
and S205, after the insulation level monitoring device with the number of n finishes the direct-current voltage injection and the insulation level calculation state t1, the step S201 is re-entered to realize circulation.
5. The method of claim 4, wherein the time t1 for the DC voltage injection and insulation level calculation state is not less than 60 s.
6. The method according to any one of claims 1 to 5, wherein the step of obtaining the DC insulation resistance of the medium voltage power system to be monitored according to the system insulation resistance calculation method so as to obtain the insulation state of the medium voltage power system comprises the steps of:
s301, when the difference between the system insulation resistance obtained by calculation of each insulation level monitoring device and the average value of all the system insulation resistances except the current monitoring device is not more than 50%, the insulation resistance of the current insulation level monitoring device is determined to be the effective system insulation resistance;
s302, taking the average value of all effective system insulation resistances as the system insulation resistance of the power system to be monitored;
and S303, calculating the average value of the insulation resistance values of the load side under the non-injection direct-current voltage obtained in the round sequence control, wherein the feeder line where the insulation level monitoring device with the minimum value is located is the feeder line with the weakest system insulation level.
7. The method according to any one of claims 1 to 5, wherein the step of arranging a plurality of insulation level monitoring devices, injection resistors, isolation capacitors and Hall current sensors on a plurality of buses and a plurality of feeders of a medium-voltage power system by using a direct-current voltage injection method comprises the following steps: the insulation level monitoring device comprises a medium-voltage power system, wherein an insulation level monitoring device, three injection resistors and a blocking capacitor are uniformly arranged at different positions of a plurality of buses and a plurality of feeders of the medium-voltage power system, one ends of the three injection resistors are sequentially connected with A, B, C three-phase medium-voltage buses or feeders of the medium-voltage power system, the other ends of the three injection resistors are connected in a star connection mode, star midpoints of the three injection resistors are connected with the insulation level monitoring device, all high-voltage side connection places in the medium-voltage power system are grounded through the isolation capacitor, Hall current sensors are arranged near the insulation level monitoring device, and A, B, C three-phase medium-voltage buses or feeders penetrate through the Hall current sensors in the direction from a bus power supply to a load side.
8. The device for monitoring the insulation level of the medium-voltage power system is characterized by comprising an analog quantity detection module, a direct-current voltage generation module, a core control module, a communication module and a human-computer interface; the analog quantity monitoring module is used for monitoring analog quantities such as Hall current, direct current voltage and the like, the direct current voltage generating module is a direct current power supply and is used for being injected into an insulation level monitoring system of a medium-voltage power system, the core control module is a controller, a gradient voltage method module, a wheel sequence control method module, a two-state operation module and a system insulation resistance calculation method module are embedded into the core control module, the communication module is used for communication, and the human-computer interface is used for data display.
9. A medium voltage power system insulation level monitoring system, characterized by that, it is made up of many insulation level monitoring devices, injection resistance, isolating capacitor, Hall current sensor, its monitoring process is the medium voltage power system insulation level monitoring method of any claim 1-7.
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