CN102694372A - Monitoring and arc protecting system for switch cabinet - Google Patents

Abstract

The invention relates to a running state monitoring and arc protecting system for a switch cabinet, which belongs to the monitoring and relay protection field of electric equipment. The system consists of a host machine and a slave machine which are both controlled by a DSP (Digital Signal Processor) and adopt field bus communication. A digital temperature sensor is used for monitoring the temperature in the switch cabinet; and an ultraviolet sensor is used for detecting partial discharge in the switch cabinet and ultraviolet rays emitted by short circuit arcs. The system has the characteristics that temperature rise or partial discharge caused by abnormal operation of the switch cabinet can be detected and a warning signal can be given out immediately to prevent the switch cabinet from short troubles. If the switch cabinet is suddenly short-circuited, the system can immediately detect the ultraviolet rays emitted by the arcs, rapidly transmit information through an advanced field bus and quickly and selectively clear faults.

Description

Switchgear monitoring and arc protection systems

technical field

The invention relates to a switchgear operating state monitoring and arc protection system, which belongs to the field of electrical equipment monitoring and relay protection in power plants and substations.

Background technique

Switch cabinets are important electrical equipment in power plants and substations. A short circuit can occur inside the switchgear and an arc will be generated at the point of the short circuit. In order to ensure the selectivity of the action of conventional relay protection, after a short circuit occurs inside the switchgear, in many cases, the fault removal time is often greater than 100ms. Therefore, the energy of the short-circuit arc is very large, and high temperature and pressure are formed in the closed switch cabinet, which will not only damage the components in the switch cabinet, but may also cause the switch cabinet to burn or explode, endangering personal safety and causing long-term power outages and production shutdowns. In order not to damage the switch cabinet when a short circuit occurs inside the switch cabinet, to ensure personal safety and to shorten the power outage time as much as possible, the duration of the short circuit current should be less than 100ms. Since arcing often occurs at short-circuit points, arc protection devices can be used for this purpose.

The currently used arc protection device is usually composed of a host and a slave, and the RS485 communication method is used between the host and the slave. But the anti-jamming ability and communication fault-tolerant ability of RS485 communication are not ideal enough.

Partial discharge occurs in some switchgear due to insulation aging, air pollution, humidity or loose components. At present, partial discharge monitoring devices are generally not installed in switch cabinets, and if partial discharge occurs, an alarm signal cannot be issued. If the operating state of the switchgear continues to deteriorate, the partial discharge may develop into a short-circuit fault.

Due to various abnormal conditions such as overload, poor connection of wires or components, the temperature inside the switchgear may rise. At present, temperature monitoring devices are generally not installed in switch cabinets. If the on-duty staff uses a handheld infrared thermometer to measure the temperature of the wires or components in the switch cabinet every day, it is not only troublesome but also prone to failure to open the door of the switch cabinet.

The LCD liquid crystal display screen of the arc protection device currently produced can only display Chinese characters, letters and numbers, and cannot display curves, which is not conducive to status monitoring and fault analysis.

Therefore, it is necessary for the arc protection device to adopt a more advanced communication method, use a high-resolution LCD liquid crystal display to display curves, and increase partial discharge monitoring and temperature monitoring functions.

Contents of the invention

The purpose of the present invention is to provide a switchgear monitoring and arc protection system: by detecting the temperature and ultraviolet intensity in the switchgear, timely and accurately discover the phenomenon of overtemperature and partial discharge inside the switchgear, and give an alarm signal, so that the on-duty personnel have a plan Overhaul the switchgear in a timely manner to prevent abnormal conditions from developing into short-circuit faults; detect arc short-circuit faults inside the switchgear, transmit information quickly and reliably through advanced fieldbus communication technology, issue a trip command within 2ms, and quickly and selectively remove faults. Ensure switchgear and personal safety, shorten power outage time, and reduce power outage scope.

The technical scheme that the present invention adopts is as follows:

The proposed switchgear operating status monitoring and arc protection method includes the following steps:

Switchgear monitoring and arc protection system, including master and slave, characterized in that both master and slave include digital signal processor, ultraviolet sensor, digital temperature sensor, current converter, tripping relay, signal relay and high resolution LCD liquid crystal display, field bus communication is adopted between the master and the slave; the ultraviolet sensor is installed in the busbar room and cable room of the switch cabinet, and the ultraviolet sensor is connected to the optical receiver through the optical fiber, and the voltage signal output by the optical receiver is conditioned After being converted with A/D, it is sent to the digital signal processor, if the ultraviolet intensity is greater than the partial discharge fixed value, but less than the short circuit fixed value, then the digital signal processor sends a partial discharge alarm signal; the digital temperature sensor is installed on In the busbar room and cable room of the switch cabinet, the temperature sensor is connected to the peripheral communication port of the digital signal processor through the signal line, and the digital signal processor completes the temperature value calculation and logic judgment function. If the measured actual temperature is greater than the temperature set value , the digital signal processor sends out an alarm signal.

The ultraviolet sensor is used to detect ultraviolet rays emitted by partial discharges and short-circuit arcs. There are two UV intensity settings, the smaller one is the partial discharge value, which is used to judge whether partial discharge occurs; the larger one is the short circuit value, which is used to judge whether a short circuit fault occurs.

The arc protection of the system can adopt the single criterion of arc light, or the double criterion of arc light and overcurrent. If the arc single criterion is used, as long as the ultraviolet intensity is greater than the short circuit setting value, a trip command is issued to trip the circuit breaker. If the double criterion of arc light and overcurrent is used, when the ultraviolet intensity is greater than the short circuit setting value and the incoming line current is greater than the overcurrent setting value, the trip command will be issued to trip the circuit breaker. The ultraviolet light of the outlet switch cabinet is detected by the slave, and the incoming current is detected by the master. The host computer and the slave machine adopt field bus such as CAN bus, Profibus, Foudation Fieldbus or LonWorks bus communication, and each DSP has two field bus controllers.

It adopts 320*240 dot matrix high-resolution LCD liquid crystal display, which can display the waveform of analog input during normal operation, and can also display the waveform of fault recording.

The beneficial effects of the present invention are: (1) Adopting a digital temperature sensor with high precision and strong anti-interference ability can automatically monitor the temperature in the switch cabinet in real time, and can detect the temperature rise caused by the abnormal state of the switch cabinet in time, and prevent the switch cabinet from The state of the cabinet is further deteriorated, reducing the failure rate. (2) Continuous real-time monitoring of the ultraviolet intensity in the switchgear can reliably detect partial discharges caused by insulation aging, air pollution, moisture or loose components, etc., and send an alarm signal. As long as the switchgear is treated in time, the partial discharge can be prevented from developing into a short circuit fault. (3) The adopted fieldbus controller works in a multi-master mode, and has a high communication rate and reliable communication, so the system of the present invention can quickly and selectively and reliably remove arc short-circuit faults inside the switchgear. The use of fieldbus communication can improve the anti-interference ability and communication fault-tolerant ability. Since each DSP has two field bus controllers, the hardware structure can be simplified and the product quality can be improved.

Description of drawings

Fig. 1 is a block diagram of the host hardware system of the present invention.

Fig. 2 is a configuration diagram of the master and the slave of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

The system proposed by the invention consists of a master and a slave, and can be used in a medium-voltage or low-voltage switchgear as a temperature monitoring, partial discharge monitoring and arc short-circuit protection device. The following takes the application of medium voltage switchgear as an example to describe the specific implementation plan.

Each master and slave unit has 4 temperature sensors and 4 UV sensors. Two temperature sensors and two ultraviolet sensors are respectively installed in the busbar room and cable room of each switch cabinet. The digital temperature sensor is connected to the peripheral communication port of the digital signal processor (DSP) through the signal line, and the DSP issues a command to make the four temperature sensors perform temperature conversion uniformly, and then the DSP reads the temperature values one by one. If the actual temperature measured by the slave is greater than the temperature setting value for a period of time, the slave transmits information to the host through the field bus, and the host sends an order to close the outlet contact of the signal relay and send an alarm signal.

The ultraviolet sensor is connected to the optical receiver through an optical fiber. After the electrical signal output by the optical receiver is conditioned by the amplification and filtering circuit, the ultraviolet intensity value is obtained through sampling and holding and A/D conversion. If the slave machine detects the partial discharge phenomenon, the slave machine actively transmits partial discharge information to the host computer through the field bus, and the host computer sends out an alarm signal.

If the slave machine detects a short-circuit arc in the cable room of the outgoing switch cabinet, and the master detects an overcurrent of the incoming line, the master actively broadcasts the overcurrent information to the slave machine through the field bus, and the slave machine judges that the cable room of the outgoing line switch cabinet is short-circuited. Then the slave sends a command to close the outlet contact of the solid state relay and trip the outlet circuit breaker.

If the slave machine detects that there is a short-circuit arc in the bus room of the outlet switch cabinet, the slave machine will actively send short-circuit information to the master machine through the field bus. If the main engine detects the overcurrent of the incoming line at the same time, the main engine sends a trip command to trip the incoming line circuit breaker and the tie circuit breaker.

After sending a trip command or an alarm signal, the LCD display will display relevant information and curves, and the host will transmit the relevant information to the upper system management machine through RS485, Ethernet or field bus.

The block diagram of the host hardware system is shown in Figure 1, and the block diagram of the slave hardware system is similar to that of the host. The configuration diagram of the master and slave is shown in Figure 2. For the sake of clarity, the temperature sensor and current converter are not shown in Figure 2.

Claims (5)

1. Switchgear monitoring and arc protection system, including a host and a slave, characterized in that both the host and the slave include a digital signal processor, an ultraviolet sensor, a digital temperature sensor, a current converter, a tripping relay, a signal relay and a high High-resolution LCD liquid crystal display, fieldbus communication is adopted between the master and the slave; the ultraviolet sensor is installed in the busbar room and cable room of the switch cabinet, and the ultraviolet sensor is connected to the optical receiver through an optical fiber, and the voltage signal output by the optical receiver After conditioning and A/D conversion, it is sent to the digital signal processor. If the ultraviolet intensity is greater than the partial discharge fixed value but less than the short circuit fixed value, the digital signal processor sends a partial discharge alarm signal; the digital temperature sensor Installed in the busbar room and cable room of the switch cabinet, the temperature sensor is connected to the peripheral communication port of the digital signal processor through the signal line, and the digital signal processor completes the temperature value calculation and logic judgment function, if the measured actual temperature is greater than the temperature value, the digital signal processor sends out an alarm signal. 2. The switchgear monitoring and arc protection system according to claim 1, characterized in that: the ultraviolet light of the outgoing switchgear is detected by the slave, and the incoming current is detected by the master. If an arc short circuit occurs in the cable room of the outgoing switchgear, the slave The main unit issues a trip command to trip the outgoing line circuit breaker; if an arc short circuit occurs in the bus room of the outgoing line switchgear, the main unit sends a trip command to trip the incoming line circuit breaker. 3. The switchgear monitoring and arc protection system according to claim 1 or 2, characterized in that: the arc protection of the system adopts the single criterion of arc or the double criterion of arc and overcurrent: when using the single criterion of arc, as long as When the ultraviolet intensity is greater than the short-circuit setting value, a trip command will be issued to trip the circuit breaker; Circuit breaker tripped. 4. switchgear monitoring and arc protection system according to claim 1, is characterized in that: described fieldbus adopts CAN bus, Profibus, Foudation Fieldbus or LonWorks bus; Each described digital signal processor has two fieldbuses controller. 5. The switchgear monitoring and arc protection system according to claim 1, characterized in that: said high-resolution LCD liquid crystal display shows the waveform of analog input during normal operation or the waveform of fault recording.

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