CN-122017494-A - Insulation impedance monitoring device of light-storage direct-current flexible direct-current power distribution system

Abstract

The invention provides a direct current micro-grid insulation impedance monitoring device for an optical storage direct-flexible system, which comprises a detection circuit and a controller communicated with the detection circuit. The device is connected into a plurality of paths of positive direct current buses including distributed photovoltaic branches and energy storage system branches in a direct current micro-grid through a Y-type connecting circuit, and a controller is used for switching relay logic to obtain output voltage signals. The core decision logic is used for comparing whether the output voltage is in a reasonable interval defined by a coefficient gamma (the value of which can be dynamically adjusted according to the energy storage voltage class) and the bus voltage, so that the insulation abnormality of the direct current micro-grid system under the flexible interaction working condition is rapidly identified and an alarm is sent out. The device simplifies the operation flow of multi-branch complex impedance, and remarkably improves the detection efficiency of the insulation state of the direct current end to the ground.

Inventors

• ZHANG JIZHENG
• LIU QIYANG
• CHEN ZIDONG

Assignees

• 帝森克罗德集团有限公司

Dates

Publication Date

20260512

Application Date

20260303

Claims (10)

1. 1. The insulation impedance monitoring device of the light storage direct-soft direct-current power distribution system is characterized by comprising a detection circuit and a controller in bidirectional communication with the detection circuit, wherein the input end of the detection circuit is respectively connected with a first power branch direct-current bus and a second power branch direct-current bus of a direct-current micro-grid, three detection circuits are contained in the detection circuit, a Y-type connection method is adopted among the three detection circuits, and the controller is used for executing the following steps to determine insulation impedance: transmitting a first control signal to the detection circuit, and starting a third relay (RY 3) connected with the common terminal; Transmitting a second control signal, and simultaneously starting a first relay (RY 1) and a second relay (RY 2) to acquire output voltage signals of the two paths of positive direct current buses after being connected into a Y-type circuit; and judging the magnitude relation between the product of the coefficient gamma and the output voltage of the power supply branch and the output voltage of the controller provided by the detection circuit, and sending out an insulation fault alarm if the output voltage is not within the range defined by the gamma 1 multiplied by the output voltage and the gamma 2 multiplied by the output voltage.
2. 2. The insulation resistance monitoring device of the light Chu Zhirou direct-current distribution system according to claim 1, wherein the calculation logic of the coefficient gamma is that under the state that the relays RY1 and RY2 are simultaneously started, the output voltage V1 of the first power supply branch, the output voltage V2 of the second power supply branch and the output voltage signal V3 of the detection circuit are obtained, and based on the relation of the current sum of the Y-shaped connection circuit to 0, the functional proportion relation between the output voltage V3, the input voltages V1 and V2 and the detection resistor R V1 、R V2 is established; The configuration method of the coefficient gamma comprises the steps of presetting determination extremum R min and R max of insulation impedance, substituting the determination extremum R min and R max into detection resistance items in the function proportion relation respectively, and calculating an upper limit proportion coefficient gamma 1 and a lower limit proportion coefficient gamma 2 for an insulation fault determination range.
3. 3. The insulation impedance monitoring device of the light Chu Zhirou direct current distribution system according to claim 2, wherein the detection circuit comprises a first switch circuit, a second switch circuit and a third switch circuit, the first switch circuit, the second switch circuit and the third switch circuit are respectively connected in parallel, a Y-type connection method is adopted among the first switch circuit, the second switch circuit and the third switch circuit, and positive direct current bus voltage signals of the first power branch and the second power branch are respectively detected by the first switch circuit and are output to the controller through the third switch circuit.
4. 4. The insulation resistance monitoring device of the light Chu Zhirou direct-current distribution system according to claim 3, wherein the first switch circuit comprises a relay RY1, resistors R1-R2, a capacitor C1, a MOS tube Q1, a diode D1 and a zener diode ZD1, a1 pin of RY1 is connected with a Pv1_ISO_TEST, a2 pin is connected with the first detection circuit, and a 5 pin is connected with a control signal line through the MOS tube Q1 and the resistor R1.
5. 5. The insulation resistance monitoring device of the light Chu Zhirou direct-current distribution system according to claim 4, wherein the second switching circuit comprises a relay RY2, resistors R4-R5, a capacitor C2, a MOS transistor Q2, a diode D2 and a zener diode ZD2, wherein a1 pin of RY2 is connected with a PV 2-ISO_TEST, a 2 pin is connected with a second detection circuit, and a5 pin of the second switching circuit is connected with a control signal line through the MOS transistor Q2.
6. 6. The insulation resistance monitoring device of the light Chu Zhirou direct-current distribution system according to claim 5, wherein the third switching circuit comprises a relay RY3, resistors R7-R8, a capacitor C3, a MOS transistor Q3, a diode D3 and a zener diode ZD3, wherein a pin 1 of RY3 outputs a PV_ISO signal to the controller, and a pin 2 is connected with the third detection circuit.
7. 7. An optical Chu Zhirou dc distribution system insulation resistance monitoring device as in claim 3 wherein the first detection circuit comprises a resistor R3 and a detection resistor RV1 in parallel, one end of R3 being connected to pin 2 of relay RY1 and the other end being connected to ground FGND.
8. 8. The apparatus for monitoring insulation resistance of an optical Chu Zhirou dc distribution system according to claim 7, wherein the second detection circuit includes a resistor R6 and a detection resistor RV2 connected in parallel, one end of R6 is connected to pin 2 of the relay RY2, and the other end is connected to the ground FGND.
9. 9. The optical Chu Zhirou dc distribution system insulation resistance monitoring device as defined in claim 8, wherein the third detection circuit includes a resistor R9 having one end connected to pin 2 of relay RY3 and the other end connected to ground FGND.
10. 10. A method for monitoring insulation resistance of an optical Chu Zhirou dc microgrid based on the device of any one of claims 1 to 9, comprising the steps of: the controller sends a first control signal to the detection circuit, and opens the relay RY3; after the first threshold time passes, sending a second control signal, simultaneously starting RY1 and RY2, and waiting for the second threshold time; receiving a voltage signal V3 fed back by the detection circuit, and acquiring the output voltage V1 of the power supply branch according to the logic of claim 2 or 4; judging whether the output voltage V3 satisfies a judging section of gamma 2 XV 1< V3< gamma 1 XV 1, and if not, judging that the insulation is problematic and giving an alarm.

Description

Insulation impedance monitoring device of light-storage direct-current flexible direct-current power distribution system Technical Field The invention belongs to the field of direct-current power distribution and building comprehensive energy safety, and particularly relates to a direct-current bus insulation impedance monitoring device in an optical storage direct-flexible system. Background In a light Chu Zhirou (PEDF) system, the ground insulation resistance of a direct current micro-grid bus (positive electrode and negative electrode) is a key index for guaranteeing the safe operation of a building integrated energy system. Because photovoltaic module, energy storage facility and power electronic equipment long-term operation are influenced by environmental temperature and humidity change, electrical aging or physical friction, extremely easily lead to insulating properties to drop, and then cause electric leakage or conflagration risk. The existing detection technology mainly relies on the traditional bridge method, and the impedance is determined by switching in a resistor network and calculating a voltage value, but the mode has the defects of logic redundancy calculation, low response speed and the like, and is difficult to meet the requirement of efficient protection. In particular, under the light Chu Zhi flexible environment, the system integrates distributed photovoltaic, energy storage batteries and flexible electric equipment, the topology of the internal branch of the direct current micro-grid is complex, and the bus voltage frequently fluctuates along with flexible scheduling. The traditional single-point bridge method is difficult to realize high-frequency and high-precision rapid monitoring while considering the switching of the charging and discharging working conditions of the energy storage system, so that a high-performance insulation monitoring scheme capable of adapting to the dynamic direct current working condition is needed. Disclosure of Invention In order to solve the problems, the invention provides a direct current bus insulation impedance monitoring device in an optical storage direct-flexible system, which comprises a detection circuit and a controller in bidirectional communication with the detection circuit, wherein the input end of the detection circuit is respectively connected with a first power supply branch (such as light Fu Zhilu) positive direct current bus and a second power supply branch (such as energy storage branch) positive direct current bus power supply branch of a direct current micro-grid, three detection circuits are contained in the detection circuit, a Y-type connection method is adopted among the three detection circuits, and the controller is used for executing the following steps to determine insulation impedance: transmitting a first control signal to the detection circuit, and starting a third relay (RY 3) connected with the common terminal; Transmitting a second control signal, and simultaneously starting a first relay (RY 1) and a second relay (RY 2) to acquire output voltage signals of the two paths of positive direct current buses after being connected into a Y-type circuit; and judging the product of the coefficient gamma and the output voltage of the power supply branch and the magnitude relation between the output voltage of the detection circuit and the controller (the value of gamma can be dynamically adjusted according to the energy storage voltage class), and if the output voltage is not within the range defined by gamma 1 multiplied by the output voltage and gamma 2 multiplied by the output voltage, sending out an insulation fault alarm. The further insulation impedance monitoring device of the light Chu Zhirou direct-current distribution system comprises calculation logic of the coefficient gamma, a function proportion relation between the output voltage V3 and the input voltages V1 and V2 and between the output voltage V3 and the detection resistor R V1、RV2, wherein the calculation logic is used for acquiring the output voltage V1 of the first power supply branch, the output voltage V2 of the second power supply branch and the output voltage signal V3 of the detection circuit under the state that the relays RY1 and RY are simultaneously started; The configuration method of the coefficient gamma comprises the steps of presetting determination extremum R min and R max of insulation impedance, substituting the determination extremum R min and R max into detection resistance items in the function proportion relation respectively, and calculating an upper limit proportion coefficient gamma 1 and a lower limit proportion coefficient gamma 2 for an insulation fault determination range. The further insulation impedance monitoring device of the light Chu Zhirou direct-current distribution system comprises a first switch circuit, a second switch circuit and a third switch circuit, and the first switch circuit, the second switch circuit and the