Unsa ang papel sa microcomputer integrated protection device sa high-voltage switchgear, ug unsaon nimo pagpili niini?

Ang Role ug Pili sa Microcomputer Integrated Protection Devices sa High-Voltage Switchgear

Sa mga nagkalabayang tuig, ang paggamit sa microcomputer integrated protection devices sa medium- ug high-voltage power distribution system projects adunay kaayo nga nahimong pagtaas. Ang mga device niini mas user-friendly ug nakakab-ot sa mga drawback sa tradisyonal nga relay protection sama sa komplikado nga wiring, baho nga reliability, ug hulagpos nga setting ug debugging procedures. Ang microcomputer integrated protection devices mayda comprehensive self-diagnostic functions, makahimo kini og detection ug commissioning nga maayo ra mogamit.

Kon natukod ang anomalya, ang central processing unit (CPU) magmando sa signal generator aron mobuong corresponding nga audible ug visual alarm signals. Sa daghan pa, ang iba pang auxiliary functions madali ra mogamit, sama sa printing sa fault information ug recording sa oras sa protection actions human sa event. Adunay daghang manufacturers nga nagproduce niining mga device, tungod kay bisan asa mayda products nga mayda uban nga functionalities ug hardware configurations, mahirap makuha ang pinaka suitable nga integrated protection device.

I. Pili sa Microcomputer Integrated Protection Devices

Arkon sa pag-ensure nga ang microcomputer integrated protection devices mahimong tama ug accurate sa pagbuhat sa ilang relay protection tasks, ang pili sa design phase dapat batasan sa comprehensive evaluation sa reliability, response time, maintenance ug commissioning ease, ug additional functions.

1.1 Reliability sa Microcomputer Integrated Protection Devices

Ang signal input sa microcomputer integrated protection devices sama sa tradisyonal nga relay protection: voltage ug current signals gipangutana gikan sa voltage transformers (VTs) ug current transformers (CTs), giconvert sa transducers ngadto sa standard signals nga required sa protection device, ug filtered aron malikayan ang low- ug high-order harmonics ug uban pang interference signals. Ang Analog-to-digital (A/D) converters mao ang mogtransform sa analog signals ngadto sa digital signals. Ang CPU magbuhat sa computations sa digital input, magcompare kini sa preset values, magjudge, ug magdecide kon unsaon ang trigger an alarm o trip.

Arkon sa pag-fulfill sa reliability requirements, ang measurement ug protection input signals giprocess ug output gikan sa independent processing units sa device. Kini nagpadayon sa taas nga measurement accuracy ug nagprovide og ample margin sa severe faults. Ang device dili mag-experience og A/D overflow o saturation kon ang fault signal current nareach 20 times sa normal value, kini generally satisfies sa reliability requirements sa typical engineering applications.

1.2 Response Time sa Microcomputer Integrated Protection Devices

Sa panahon sa design ug pili, ang kalidad sa protection device mahatagan lang og judgment batasan sa three indicators: computational accuracy, response time, ug computational load. Ang tatlo ka factors mao ang mutually contradictory: lower computational accuracy ug smaller computational load lead to faster response times, while higher accuracy ug larger load result in slower response times. Generally, para sa end-users sa power grid, ang computational load dapat mas taas kay sa 3 times, ang computational accuracy dapat mas taas kay sa 0.2%, ug ang maximum response time dapat less than 30 ms aron mapasabot sa typical engineering requirements sa response time.

1.3 Pili sa Iba pang Functions sa Microcomputer Integrated Protection Devices

Ang integrated protection devices mayda daghan nga integrated chips, requiring high-level technical expertise sa pag-maintenance. Sa panahon sa pili, ang devices nga modular ug universal hardware dapat preferred, allowing hardware faults resolbaron sa simple replacement sa modules, thereby improving work efficiency.

Sa daghan pa, ang protection device dapat mayda built-in EPROM module, enabling all setting values matago digital. Ang field personnel makapangita sa mga settings niini sa equipment commissioning walay need sa pag-rewrite sa data. Aron integrar sa overall project's automated monitoring system, ang protection device dapat mayda communication capabilities, allowing easy network formation via data buses ug enabling the transmission of action information sa higher-level automated monitoring system.

2. Relationship Tungod sa Integrated Protection Devices ug ang Plant-Wide Automation Control System

Batason sa configuration ug communication requirements sa plant automation control system, ang automation system para sa microcomputer integrated protection devices typically divided into three layers: ang switchgear layer, substation layer, ug central control room.

2.1 Switchgear Layer

Ang switchgear layer mayda daghan nga types sa microcomputer integrated protection devices, directly installed sa switchgear. Ang bawat device direktso mohandle sa measurement, protection signals, ug control functions sa ilang respective cabinet. Ang specific functions mao ang sumala:

(1) Incomer Cabinet

• Protection Functions: Instantaneous overcurrent tripping, time-delayed overcurrent tripping.

• Measurement Functions: Three-phase current, three-phase voltage, active ug reactive power, active ug reactive energy.

• Monitoring Functions: Circuit breaker open/closed position.

• Control Functions: Manual open/close (sa cabinet), remote control open/close.

• Alarm Functions: Trip due to fault, warning signals, open/close, device fault, fault recording, etc.

(2) Transformer Cabinet

• Protection Functions: Instantaneous overcurrent tripping, time-delayed overcurrent tripping, inverse-time overloading, single-phase ground fault, heavy gas trip.

• Measurement, Monitoring, ug Control Functions: Same as incomer cabinet.

• Alarm Functions: Trip due to fault, light gas, temperature alarm, warning signals, open/close, device fault, fault recording, etc.

(3) Busbar Cabinet

• Protection, Monitoring, ug Control Functions: Same as incomer cabinet.

• Alarm Functions: Trip due to fault, device fault, fault recording, etc.

(4) Motor Cabinet

• Protection Functions: Instantaneous overcurrent tripping, time-delayed overcurrent tripping, overload, single-phase ground fault, low voltage, overheat.

• Measurement Functions: Three-phase current, three-phase voltage, active ug reactive power, active ug reactive energy.

• Monitoring Functions: Circuit breaker open/closed position.

• Control Functions: Manual open/close (sa cabinet), remote control open/close.

• Alarm Functions: Trip due to fault, warning signals, open/close, device fault, fault recording, etc.

Human sa data acquisition sa ilang respective switchgear, ang protection devices magtransmit sa data via bus sa monitoring computer sa substation layer. Kini nga sistema significantly reduces control cables, shortens on-site commissioning time, ug improves work efficiency.

2.2 Substation Layer

Daghan nga signals gikan sa substation dapat transmit sa central control room via plant's industrial Ethernet, ug ang substation mokuyog signals gikan sa central control room aron mobuong control commands sa protection devices. Ang substation layer typically consists sa industrial control computers, printers, ug monitors. Ang main functions niana include configuring ug managing sa switchgear integrated protection devices, monitoring system operation, establishing ug managing sa substation database, ug communicating sa central control room.

Tungod sa manufacturers keeping their protection device software ug electrical calculation methods confidential, ang substation layer must also handle communication protocol conversion aron facilitate signal transmission ug reception between the central control room ug protection devices.

2.3 Communication Network

Communication between the switchgear ug substation can use a MODbus bus network, supporting up to 64 slave stations. Optical isolation is used between the communication network ug devices to prevent external interference. Communication between the substation ug central control room uses an industrial Ethernet with a fiber-optic medium, with a communication rate greater than 1 Mbps.

2.4 Software

System software can use mainstream platforms with international standard architectures, such as Windows NT. Software modules should include: main control software, graphics software, database management software, report generation software, ug communication software.

When selecting software, the main control software should have a high degree of modularity. High modularity allows field personnel to readily call up software based on site conditions without additional programming, greatly reducing the operational ug maintenance workload for dispatchers ug maintenance personnel ug improving work efficiency.

3. Issues to Note When Selecting Hardware for Microcomputer Integrated Protection Devices

Additionally, the following issues should be noted when selecting hardware for microcomputer integrated protection devices:

• Use a sealed, reinforced chassis that is resistant to strong vibration ug interference, with a compact installation size suitable for harsh environments ug cabinet mounting.

• Adopt an industrial-grade dual-CPU structure, with each device containing a main CPU ug a communication CPU. The two CPUs work in a mutual-checking mode, improving the device's response time ug accuracy, preventing maloperation or failure to operate, ug enhancing stability ug reliability.

• Full-range temperature automatic compensation allows the device to operate long-term in environments from -20°C to +60°C.

• Measurement ug protection signals are processed separately within the device, meeting both accuracy requirements ug protection range ug reliability requirements.

• Use a dedicated frequency sampling circuit to precisely track grid frequency, making electrical quantity calculations more accurate.

• Use optical isolation for digital input ug output signals, ug shielded cables for internal cabinet wiring, effectively preventing external interference signals ug improving the device's anti-interference capability.

• Use a large-screen LCD display ug soft keyboard for clearer numerical display ug easier operation.

• After commissioning ug operation, the setting values for various protection modes are stored digitally in EPROM, allowing for easy recall after debugging or circuit fault repair.

• Include a comprehensive circuit breaker control circuit suitable for controlling various types of circuit breakers, facilitating substation upgrades.

• Have comprehensive accident analysis capabilities, including protection action event records, electrical quantity signal limit exceedance records, ug fault recording.

4. The Role of Microcomputer Integrated Protection Devices in High-Voltage Switchgear

Microcomputer protection devices safeguard circuits against abnormal conditions. Their roles in high-voltage switchgear are as follows:

Microcomputer protection devices possess strong data processing, logical operation, ug information storage capabilities, featuring an advanced internal architecture. They offer the complete protection functions of conventional relay protection. By receiving signals from measurement components such as current transformers ug voltage transformers, the device can monitor, control, ug protect the circuit state. This includes protection against short circuits, overloads, single-phase ground faults, etc. Without a protection device, these functions in a high-voltage switchgear are achieved using relays. With microcomputer protection, additional functions are available, such as easy acceptance of remote control, communication with the upper-level system to transmit current, voltage, power, ug energy signals from the circuit, ug convenient adjustment of protection settings.