CN204008808U - Alternating current is scurried into the detection of straight-flow system and is compeled to jump device - Google Patents

Abstract

The utility model relates to a detection and forced trip device for alternating current intruding into a direct current system, which is characterized in that: the positive busbar (+KM) of the direct current system is connected to an input of an alternating current signal transmitter through a first direct current blocking capacitor (C1) terminal, and the negative busbar (-KM) of the DC system is connected to the other input terminal of the AC signal transmitter through the second DC blocking capacitor (C2), the output terminal of the AC signal transmitter is connected to the microprocessor, and the microprocessor The two ports of the processor are respectively connected to the control terminal of the first optocoupler (OP1) and the control terminal of the second optocoupler (OP2), and the output terminal of the first optocoupler (OP1) is connected to the first contactor (S1) The coils of the second optocoupler (OP2) are connected in series with the coil of the second contactor (S2). The utility model realizes on-line real-time detection of AC channeling and DC faults, and at the same time can force an AC or DC switch on the AC channeling circuit to isolate the fault branch.

Description

Detecting and forced tripping device for alternating current intrusion into direct current system

technical field

The utility model relates to a detection and forced trip device for alternating current intruding into a direct current system.

Background technique

In the substation, the DC system provides DC power for control, signal, relay protection, automatic device and emergency lighting, etc. The stable and reliable operation of the DC power supply plays a very important role in the safety and stability of the power system. However, due to the wide coverage of the DC system and the complex environment, faults of AC intrusion into the DC system occur from time to time, which can cause serious accidents such as metallic grounding of the DC system, false alarms of monitoring devices, and misoperation of relay protection devices, which are extremely harmful. According to the "Eighteen Major Power Grid Anti-Accident Measures of the State Grid Corporation" [2012]: "5.1.1.18.3 Newly built or renovated substations, DC system insulation monitoring devices should be equipped with AC channeling DC fault measurement and alarm Function. The original DC system insulation monitoring device should be gradually transformed to make it have the function of measuring and alarming AC channeling DC faults. Therefore, it is very necessary to monitor and control AC channeling DC faults.

At present, there are also some detection methods and equipment for the fault of AC crossing into the DC system, which can test the amplitude of the crossing AC and the specific fault circuit, but they all have the disadvantage of single function, can only detect and cannot be treated.

Utility model content

The purpose of this utility model is to provide a detection and forced trip device for alternating current intruding into a direct current system, which can detect the insulation state of the direct current system on-line and can force trip and disconnect the alternating current intruding into the faulty branch when necessary.

A detection and forced trip device for alternating current intrusion into a direct current system, including a positive bus bar of a direct current system and a negative bus bar of a direct current system. One input terminal, and the negative busbar of the DC system is connected to the other input terminal of the AC signal transmitter through the second DC blocking capacitor, the output terminal of the AC signal transmitter is connected to the microprocessor, and the two The ports are respectively connected to the control terminal of the first optocoupler and the control terminal of the second optocoupler, and the output terminal of the first optocoupler is connected in series with the coil of the first contactor so as to control the power on and off of the coil. The output end of the second optocoupler is connected in series with the coil of the second contactor so as to control the coil on and off; the positive busbar of the DC system is grounded through the normally open contact of the first contactor, and the The negative busbar of the DC system is grounded through the normally open contact of the second contactor.

Wherein the microprocessor is also connected with the key unit and the display unit respectively.

A first current-limiting resistor and a first diode are connected in series between the normally open contact of the first contactor and the positive bus bar of the DC system, and between the normally open contact of the second contactor and the negative bus bar of the DC system A second current limiting resistor and a second diode are connected in series between them.

A detection and forced trip device for alternating current intrusion into a direct current system, including a positive bus bar of a direct current system and a negative bus bar of a direct current system. One input terminal, and the negative busbar of the DC system is connected to the other input terminal of the AC signal transmitter through the second DC blocking capacitor, the output terminal of the AC signal transmitter is connected to the input terminal of the voltage comparator, and the voltage comparator The output ends of the first optocoupler and the control end of the second optocoupler are respectively connected, and the output end of the first optocoupler is connected in series with the coil of the first contactor so as to control the coil on and off, and the second optocoupler The output end of the optocoupler is connected in series with the coil of the second contactor so as to control the coil on and off; the positive busbar of the DC system is grounded through the normally open contact of the first contactor, and the DC system The negative bus bar is grounded through the normally open contact of the second contactor.

A first current-limiting resistor and a first diode are connected in series between the contact of the first contactor and the positive bus bar of the DC system, and there is a series connection between the contact of the second contactor and the negative bus bar of the DC system. second current limiting resistor and second diode.

The beneficial effects of the utility model are: 1. The online real-time detection of AC channeling and DC faults is realized, and at the same time, the AC or DC switch on the AC channeling circuit can be forced to isolate the fault branch, and the DC power supply and power system operation are enhanced. safety. 2. The automatic prevention and control of AC and DC series electricity is realized, eliminating the need for manual on-site operation to eliminate defects, avoiding the fatigue of going to and from the site, saving a lot of manpower and material resources, and improving work efficiency.

Description of drawings

Accompanying drawing 1 is the circuit schematic diagram of the utility model.

Detailed ways

The utility model is a detection and forced tripping device for alternating current intruding into a direct current system, as shown in Figure 1, the two dotted boxes on the right are the positive and negative series AC equivalent circuit diagrams of the direct current system, and the left dotted box is the composition of the device and block diagram.

As shown in Figure 1, one end of the first DC blocking capacitor C1 and the second DC blocking capacitor C2 are respectively connected to the DC system positive bus +KM and the DC system negative bus -KM, the first DC blocking capacitor C1 and the second DC blocking capacitor C2 The other end and the ground are respectively connected to the input end of the AC voltage transmitter (signal conditioning conditioning circuit), and its output end is connected to the A/D interface of the microprocessor to form an AC sampling loop of the device.

The key unit and the display unit are respectively connected to the keyboard and the display interface of the microprocessor to realize the input and display functions of the device, and of course neither of them can be connected. The two I/O ports of the microprocessor are respectively connected to pin 2 of the first optocoupler OP1 and the second optocoupler OP2 through the third current limiting resistor R3 and the fourth current limiting resistor R4, the first optocoupler OP1 and the second optocoupler Pin 1 of the coupling OP2 is connected to the +5 power supply, pin 4 of the first optocoupler OP1 and the second optocoupler OP2 are connected to the power supply 24+, and pin 3 of the first optocoupler OP1 and the second optocoupler OP2 are respectively connected to the first contactor S1 And one end of the coil of the second contactor S2, the other end of the coil is connected to the power supply 24-, forming a forced trip control circuit of the device.

One end of the first diode D1 and the second diode D2 are respectively connected to the DC bus +KM and -KM, and the other end of the first diode D1 and the second diode D2 are respectively connected to the first current limiting resistor R1 and one end of the second current limiting resistor R2, the other end of the first current limiting resistor R1 and the second current limiting resistor R2 are respectively connected to one end of the main (normally open) contact of the first contactor S1 and the second contactor S2, The other ends of the main contacts of the first contactor S1 and the second contactor S2 are connected together and grounded to form a forced tripping main circuit of the device, which is used for short-circuiting the alternating current and forcing tripping the AC or DC switch on the faulty branch. Among them, the first diode D1 and the second diode D2 are used to ensure the forwardness of the direction of the current flowing through the DC switch, so as to avoid the short-circuit reverse current from burning the DC switch, and the first current-limiting resistor R1 and the second current-limiting resistor R2 is used to limit the short-circuit current within a certain range, so as not to break down the diode if the short-circuit current is too large.

Obviously, the above-mentioned microprocessor can be replaced by a voltage comparator, for example, the output terminal of the AC signal transmitter is connected to the input terminal of a voltage comparator (the other input terminal of the voltage comparator is connected to the reference voltage), and the voltage The output terminals of the comparator are respectively connected to the control terminals of the first optocoupler and the second optocoupler. When the detected AC component is greater than the reference voltage, a high-level signal is output to make the first optocoupler and the second optocoupler conductive for short-circuiting and channeling AC.

The working process of the detection and forced jumping device of the alternating current into the direct current system of the utility model is as follows:

The microprocessor detects the AC component of the DC system online through two DC blocking capacitors and an AC voltage transmitter. Under normal circumstances, both the DC switch and the AC switch are in the closed state, the insulation of the AC and DC feeder branches is in good condition, there is no AC-DC channeling, and the AC-DC power supply system is in a normal working state. An optocoupler controls the normally open contacts of the two contactors to be in the disconnected state. When the insulation of AC and DC branches is lowered or faults such as manual miswiring occur, the AC live wire can pass through the AC and DC switches and enter the DC positive or negative pole, causing AC and DC series currents. At this time, the channeling AC signal passes through the isolation The straight capacitance enters the AC voltage transmitter, especially for signal isolation and conversion to meet the range of the microprocessor A/D converter, and the conditioned signal enters the microprocessor for A/D conversion and digital processing to obtain the AC signal amplitude And the series input polarity, if the AC amplitude exceeds the preset value, the microprocessor will drive the coil of the corresponding contactor through the I/O port through the corresponding optocoupler isolation according to the series polarity, so that the main contact of the contactor will be closed for 100ms , so that the AC power that enters the DC system is grounded, and a large short-circuit current is generated instantaneously, forcing the AC or DC switch on the series branch circuit to trip due to short-circuit breaking, thereby automatically eliminating AC and DC faults in time.

Obviously, the principle is basically the same when replacing the microprocessor with a voltage comparator.

The utility model provides a device for detecting and forcing an alternating current into a DC system. Under normal circumstances, a microprocessor detects the AC component of the DC system on-line through a DC blocking capacitor and an AC voltage transmitter. Once there is an alternating current entering the DC system, The microprocessor immediately detects the amplitude of the AC signal and the polarity of the series input. If the AC amplitude exceeds the set value, the microprocessor drives the corresponding contactor to close for 100ms through the corresponding optical coupler according to the polarity of the series, and short-circuits the contactor that enters the DC system. Alternating current, which produces a large short-circuit current, forces the AC or DC switch on the series branch circuit to trip, thereby automatically eliminating the AC channeling DC fault in time.

Claims (5)

1. an alternating current is scurried into the detection of straight-flow system and is compeled to jump device, comprise straight-flow system positive electrode bus (+KM) and straight-flow system negative pole bus (KM), it is characterized in that: described straight-flow system positive electrode bus (+KM) connects an input end of AC signal transmitter by the first capacitance (C1), and described straight-flow system negative pole bus (KM) connects another input end of AC signal transmitter by the second capacitance (C2), the output termination microprocessor of this AC signal transmitter, two ports of this microprocessor connect respectively the control end of the first optocoupler (OP1) and the control end of the second optocoupler (OP2), and the output terminal of this first optocoupler (OP1) and the first contactor (S1) thus coil be cascaded that to control this coil logical, power-off, the output terminal of this second optocoupler (OP2) with the second contactor (S2) thus coil be cascaded that to control this coil logical, power-off, described straight-flow system positive electrode bus (+KM) is by the normally opened contact ground connection of this first contactor (S1), and described straight-flow system negative pole bus (KM) is by the normally opened contact ground connection of this second contactor (S2).

2. alternating current as claimed in claim 1 is scurried into the detection of straight-flow system and is compeled to jump device, it is characterized in that: wherein microprocessor is also connected with display unit with push-button unit respectively.

3. alternating current as claimed in claim 1 or 2 is scurried into the detection of straight-flow system and is compeled to jump device, it is characterized in that: wherein between the normally opened contact of the first contactor (S1) and straight-flow system positive electrode bus (+KM), be also in series with the first current-limiting resistance (R1) and the first diode (D1), and be also in series with the second current-limiting resistance (R2) and the second diode (D2) between the normally opened contact of the second contactor (S2) and straight-flow system negative pole bus (KM).

4. an alternating current is scurried into the detection of straight-flow system and is compeled to jump device, comprise straight-flow system positive electrode bus (+KM) and straight-flow system negative pole bus (KM), it is characterized in that: described straight-flow system positive electrode bus (+KM) connects an input end of AC signal transmitter by the first capacitance (C1), and described straight-flow system negative pole bus (KM) connects another input end of AC signal transmitter by the second capacitance (C2), the input end of the output termination voltage comparator of this AC signal transmitter, the output terminal of this voltage comparator connects respectively the control end of the first optocoupler (OP1) and the second optocoupler (OP2), and the output terminal of this first optocoupler (OP1) and the first contactor (S1) thus coil be cascaded that to control this coil logical, power-off, the output terminal of this second optocoupler (OP2) with the second contactor (S2) thus coil be cascaded that to control this coil logical, power-off, described straight-flow system positive electrode bus (+KM) is by the normally opened contact ground connection of this first contactor (S1), and described straight-flow system negative pole bus (KM) is by the normally opened contact ground connection of this second contactor (S2).

5. alternating current as claimed in claim 4 is scurried into the detection of straight-flow system and is compeled to jump device, it is characterized in that: wherein between the contact of the first contactor (S1) and straight-flow system positive electrode bus (+KM), be also in series with the first current-limiting resistance (R1) and the first diode (D1), and be also in series with the second current-limiting resistance (R2) and the second diode (D2) between the contact of the second contactor (S2) and straight-flow system negative pole bus (KM).