CN-119044607-B - Ground insulation resistance monitoring method

CN119044607BCN 119044607 BCN119044607 BCN 119044607BCN-119044607-B

Abstract

The application discloses a method for monitoring a ground insulation resistance, which can be applied to ground insulation resistance monitoring equipment comprising a first resistor and a second resistor which are connected in series; the method can acquire the first voltage of the first resistor and the second voltage of the second resistor, determine whether the positive electrode insulation resistance to ground and the negative electrode insulation resistance to ground are abnormal or not based on the first voltage and the second voltage, and monitor the insulation performance between the positive electrode and the ground and the insulation performance between the negative electrode and the ground of the distribution network direct current control loop power supply according to the voltages of the two resistors and timely identify insulation abnormality. Therefore, the application converts the monitoring of the DC insulation performance of the power distribution network into the voltage acquisition and processing of the two resistors, dynamically monitors the DC insulation performance of the power distribution network and ensures the power supply reliability.

Inventors

BAO YUHANG
LI SHIJUN
CHEN HENGAN

Assignees

广东电网有限责任公司广州供电局

Dates

Publication Date: 20260508
Application Date: 20240909

Claims (7)

1. The ground insulation resistance monitoring method is characterized by being applied to ground insulation resistance monitoring equipment, wherein the ground insulation resistance monitoring equipment comprises a first resistor and a second resistor which are connected in series, the first resistor and the second resistor are connected in parallel with an anode ground insulation resistor and a cathode ground insulation resistor of a distribution network direct current control loop power supply, and a connection point between the first resistor and the second resistor is grounded; The method comprises the following steps: Acquiring a first voltage of the first resistor and a second voltage of the second resistor; comparing whether the first voltage and the second voltage are equal in magnitude; When the first voltage is not equal to the second voltage, determining the resistance values of the positive electrode ground insulation resistance and the negative electrode ground insulation resistance, and when the resistance value of the target ground insulation resistance is smaller than a preset insulation resistance threshold value, determining that the target ground insulation resistance is abnormal, wherein the target ground insulation resistance is the positive electrode ground insulation resistance or the negative electrode ground insulation resistance; when the first voltage is not equal to the second voltage, determining the resistance values of the positive electrode ground insulation resistance and the negative electrode ground insulation resistance includes: When the second voltage is smaller than the first voltage, determining that the resistance of the positive electrode insulation resistance to ground is infinite, and calculating the resistance of the negative electrode insulation resistance to ground based on the first voltage, the second voltage and the positive electrode insulation resistance to ground; when the first voltage is smaller than the second voltage, determining that the resistance of the negative electrode insulation resistance to ground is infinite, and calculating the resistance of the positive electrode insulation resistance to ground based on the first voltage, the second voltage and the negative electrode insulation resistance to ground; The calculating the resistance value of the negative electrode ground insulation resistance based on the first voltage, the second voltage, and the positive electrode ground insulation resistance includes: acquiring a negative electrode resistance calculation expression constructed based on a voltage division principle; calculating the resistance value of the negative electrode ground insulation resistance based on the negative electrode resistance calculation expression, the first voltage, the second voltage and the positive electrode ground insulation resistance; The negative electrode resistance calculation expression is as follows: in the formula, A ground insulation resistance for the negative electrode; is the first voltage; is the second voltage; is the first resistor; is the second resistor; and (3) insulating resistance to ground for the positive electrode.
2. The method for monitoring the insulation resistance to ground according to claim 1, wherein the insulation resistance to ground monitoring device further comprises a third resistor and a fourth resistor which have the same resistance value and are connected in series, the third resistor and the fourth resistor are connected in parallel with the first resistor and the second resistor, a connection point between the third resistor and the fourth resistor is grounded, a first switch is arranged between the third resistor and a connection point between the third resistor and the first resistor, and a second switch is arranged between the fourth resistor and a connection point between the fourth resistor and the third resistor; The obtaining the first voltage of the first resistor and the second voltage of the second resistor includes: And controlling the opening and closing of the first switch and the second switch, and acquiring the first voltage of the first resistor and the second voltage of the second resistor.
3. The method of claim 2, wherein controlling the closing of the first switch and the second switch and obtaining a first voltage of the first resistor and a second voltage of the second resistor comprises: controlling the opening and closing states of the first switch and the second switch; And acquiring the first voltage of the first resistor and the second voltage of the second resistor in different opening and closing states.
4. The method of claim 3, wherein determining whether the positive and negative insulation resistances to ground are abnormal based on the first and second voltages comprises: determining a functional relationship between the positive electrode insulation resistance and the negative electrode insulation resistance in the corresponding open-close state based on the first voltage and the second voltage in the same open-close state; And determining whether the positive electrode ground insulation resistance and the negative electrode ground insulation resistance are abnormal or not based on the functional relations under different switch states.
5. The method of claim 4, wherein the step of obtaining the first voltage of the first resistor and the second voltage of the second resistor in different open/close states comprises: Acquiring a first target voltage of the first resistor and a second target voltage of the second resistor when the first switch is closed and the second switch is opened; And acquiring a first body voltage of the first resistor and a second body voltage of the second resistor when the second switch is closed and the first switch is opened.
6. The method of claim 5, wherein determining a functional relationship between the positive insulation resistance and the negative insulation resistance in the corresponding open-closed state based on the first voltage and the second voltage in the same open-closed state comprises: Acquiring a target partial pressure expression preset to correspond to the first switch being closed and the second switch being opened, and a main partial pressure expression preset to correspond to the second switch being closed and the first switch being opened; Determining a first functional relationship corresponding to the first switch being closed and the second switch being open based on the first resistance, the first target voltage, the second resistance, the second target voltage, the third resistance, and the target voltage division expression; A second functional relationship corresponding to the second switch being closed and the first switch being open is determined based on the first resistor, the first body voltage, the second resistor, the second body voltage, the fourth resistor, and the body partial pressure expression.
7. The method of claim 6, wherein the target partial pressure expression is as follows: the subject partial pressure expression is as follows: in the formula, A ground insulation resistance for the negative electrode; is the first resistor; is the second resistor; a ground insulation resistance for the positive electrode; is the first target voltage; is the second target voltage; is the third resistor; is the fourth resistor; for the first body voltage; For the second body voltage.

Description

Ground insulation resistance monitoring method Technical Field The application relates to the technical field of power distribution networks, in particular to a method for monitoring ground insulation resistance. Background The power distribution network can transmit power from a power transmission network to various user terminals, is a bridge for connecting a power supply and users, and directly relates to whether the users can reliably use the power. Therefore, the safe and stable operation of the power distribution network is important to ensure the daily life production of people. The abnormal DC-to-ground insulation performance is a common fault of a secondary circuit of the power distribution network, and after a period of time, the abnormal DC-to-ground insulation performance is developed, the misoperation and refusal of a primary switch controlled by DC are extremely easy to cause, the power distribution network is powered off, and the power supply reliability is reduced. Based on the method, how to timely identify the DC insulation performance abnormality, so as to timely process the DC insulation performance abnormality, avoid the influence of the DC insulation resistance abnormality on the power supply reliability, and become the focus of the technicians in the field. Disclosure of Invention In view of the above, the present application provides a method for monitoring insulation resistance to ground, which is used for identifying abnormal insulation resistance to ground of direct current. In order to achieve the above object, the following solutions have been proposed: The ground insulation resistance monitoring method is applied to ground insulation resistance monitoring equipment, the ground insulation resistance monitoring equipment comprises a first resistor and a second resistor which are mutually connected in series, the first resistor and the second resistor are connected with an anode ground insulation resistor and a cathode ground insulation resistor of a distribution network direct current control loop power supply in parallel, and a connection point between the first resistor and the second resistor is grounded; The method comprises the following steps: Acquiring a first voltage of the first resistor and a second voltage of the second resistor; Based on the first voltage and the second voltage, it is determined whether the positive electrode ground insulation resistance and the negative electrode ground insulation resistance are abnormal. Optionally, the resistances of the first resistor and the second resistor are equal; determining whether the positive electrode ground insulation resistance and the negative electrode ground insulation resistance are abnormal based on the first voltage and the second voltage, comprising: comparing whether the first voltage and the second voltage are equal in magnitude; And when the first voltage is not equal to the second voltage, determining the resistance values of the positive electrode ground insulation resistance and the negative electrode ground insulation resistance, and when the resistance value of the target ground insulation resistance is smaller than a preset insulation resistance threshold value, determining that the target ground insulation resistance is abnormal, wherein the target ground insulation resistance is the positive electrode ground insulation resistance or the negative electrode ground insulation resistance. Optionally, when the first voltage is not equal to the second voltage, determining the resistance values of the positive electrode insulation resistance to ground and the negative electrode insulation resistance to ground includes: When the second voltage is smaller than the first voltage, determining that the resistance of the positive electrode insulation resistance to ground is infinite, and calculating the resistance of the negative electrode insulation resistance to ground based on the first voltage, the second voltage and the positive electrode insulation resistance to ground; And when the first voltage is smaller than the second voltage, determining that the resistance of the negative electrode ground insulation resistance is infinity, and calculating the resistance of the positive electrode ground insulation resistance based on the first voltage, the second voltage and the negative electrode ground insulation resistance. Optionally, the calculating the resistance value of the negative electrode ground insulation resistance based on the first voltage, the second voltage, and the positive electrode ground insulation resistance includes: acquiring a negative electrode resistance calculation expression constructed based on a voltage division principle; calculating the resistance value of the negative electrode ground insulation resistance based on the negative electrode resistance calculation expression, the first voltage, the second voltage and the positive electrode ground insulation resistance; The negative electr