1 Overview
Programmable Logic Controller (PLC) is a new industrial control device with simple structure, comprehensive performance and high reliability. Its outstanding advantages are: easy to use, outstanding real-time features and powerful communication capabilities. In its small unit, it contains powerful functions that make it easy to perform complex control tasks independently or through a network distributed system. With a small investment, the most efficient automation system can be obtained in the industrial field. It is very popular, especially after the special module configuration, it can greatly expand its application area while maintaining the ease of use. The PLC is small in size, compact in structure and convenient in programming. The ladder diagram programming method is oriented to general electrical technicians. It is easy to operate, easy to maintain, and easy to realize mechatronics. Therefore, it has been widely used in substation integrated automation.
The automation equipment in the integrated automation of small and medium-sized substation includes: programmable automatic monitoring device, programmable transformer automation screen, programmable microcomputer metering screen, programmable microcomputer line protection screen, programmable microcomputer synchronization system, programmable central signal screen, programmable capacitor The screen and programmable microcomputer DC power supply system all use PLC as their intelligent unit, and they can all run on the network to easily realize remote signaling, telemetry and remote control functions, replacing the traditional RTU. This paper mainly introduces the realization of transformer automation part composed of PLC in automatic substation. It is suitable for the automation transformation of old substations and the construction of new substations.
2 Transformer automation composition
In small and medium-sized substations, a transformer and its supporting equipment generally include: circuit breakers and operating units, transformers, transformer control panels, lightning arresters, differential protection screens, transformer grounding systems, etc. The following describes the automation configuration of the transformer in two cases.
2.1 Transformers and ancillary equipment are conventional equipment
If the circuit breaker and operating unit, transformer, differential protection screen, transformer lightning protection grounding system, etc. are all conventional equipment without intelligent unit and computer interface, then only the transformer control panel part should be selected as programmable (PLC) transformer automation. The screen can form a relatively complete transformer automation system. The system block diagram is shown in Figure 1. The transformer control panel and its supporting equipment in the central control room of the substation are directly connected with the programmable transformer automation screen through the cable for information exchange. The main computer monitoring system in the central control room or remote control monitors the transformer through the monitoring of the programmable transformer automation screen. The information exchange is controlled by the industrial computer (IPC) in the main computer monitoring system and the PLC in the programmable transformer automation screen. It is realized through an industrial field communication network. This kind of transformer automation system is generally suitable for retrofitting old stations or building new stations with small capital.
2.2 Transformers and ancillary equipment are intelligent equipment
If the circuit breaker and the operating unit, the transformer, the differential protection screen, and the lightning protection grounding system of the transformer all contain the intelligent unit and the computer interface, then the transformer control panel part adopts the programmable (PLC) transformer automation screen, which can be very convenient. Form a powerful transformer automation system. The system block diagram is shown in Figure 2. The transformer control panel and its supporting equipment in the central control room of the substation are exchanged with the programmable transformer automation screen through the industrial field communication network and the central control room or the remote host computer monitoring system. The programmable transformer automation screen has only a very small number of cable connections to the transformers and associated equipment. The whole system is very simple.
3 The composition and implementation of programmable transformer automation screen
The hardware equipment of the programmable transformer automation screen generally includes: PLC, PLC input/output signal isolation relay, near-ground operation button and fault alarm indicator, alarm, intelligent transformer oil temperature inspection instrument, intelligent signal test, small DC power supply , communication adapters, etc. The software mainly consists of PLC automatic monitoring program and communication program with monitoring host computer (host computer).
3.1 PLC selection
From the electrical characteristics of the above-mentioned controlled object (transformer), this system almost monitors the amount of switching. The temperature analog quantity and the signal analog quantity are all monitored by smart meters. The output contact switch quantity of the intelligent meter enters the PLC. Therefore, the PLC only needs to select the basic module and the communication module without special modules. Next, determine the number of PLC input ∕ output points, and count the number of monitoring points of the programmable transformer automation screen on the transformer and associated equipment. The general input does not exceed 64 points and the output does not exceed 40 points. In practice, we selected the Rock series PLC products developed by Beijing Ankong Technology Development Co., Ltd.: Rock E20 series PLC products. This product adopts advanced 16-bit CPU and is equipped with embedded real-time multi-tasking operating system. It can realize functions of acquisition, calculation, logic, timing, control and communication. Its single CPU+ expansion module can carry 32 modules and control 500 I∕. O point. Local expansion with RS485 or Intranet, remote expansion with dial-up Modem or GPRS. The product adopts the plug-in method to expand, the module size is small, the installation and use are convenient, the maintenance is simple, and the application is flexible, safe and reliable.
3.2 Programmable Transformer Automation Screen Hardware
The components that make up the programmable transformer automation screen should be designed and connected in strict accordance with the electrical specifications. In addition, the part connected to the PLC should be designed and connected in strict accordance with the technical requirements of the PLC manufacturer.
3.3 PLC automatic monitoring program
The different transformer composition of the substation determines the difference of the monitoring program of the programmable transformer automation screen PLC. Here, a 35KV single bus and a main transformer are taken as an example.
3.4 Realization of serial communication between PLC and monitoring host computer
4 programmable transformer automation screen operation
The programmable transformer automation screen is in an important position for real-time monitoring in the automatic operation of the transformer. It passes the input ∕ output signal isolation relay according to the substation substation equipment (isolated knife gate, circuit breaker, voltage transformer, current transformer, transformer lightning protection). Status of equipment such as grounding system ∕ Control signal, programmable logic controller (PLC) controls the above signals in real time according to the specific automation process, and transmits data to the monitoring host computer through the network. Complete the opening and closing of the transformer, operation and maintenance and relay protection (overcurrent protection, current quick-break protection, differential protection, gas protection and overload protection, etc.). It not only makes the transformer in the closed-loop automatic control, but also makes the transformer automation and the monitoring and control protection system work in coordination, so that the whole transformer is in optimal operation. Due to the characteristics of the PLC itself, each input ∕ output signal has an indicator light, making it extremely easy to maintain and repair the substation where the signal is scattered.
5 Conclusion
This system has been successfully put into operation in the automation engineering of several transformers in our city. We found that it is very easy to handle faults, which shortens the power outage maintenance time and the operation and maintenance costs are very low. In the operation, faults such as the water relay of the gas relay of the transformer, the disconnection of the electrical contacts of the contactor in the central control room, and the control circuit of the transformer can be found, alarmed and automatically entered into the processing program, and can be monitored on the host computer. Centralized monitoring. The application environment composed of PLC can be configured to meet the needs of different users or the same user in different periods. To change the organization of the system, it is only necessary to re-enter the PLC monitoring program. We are quite satisfied with this.
references:
1 Yang Shiyuan programmable controller programming application and maintenance 1995 Tsinghua University Press
2 Rock E20 Series PLC Products Beijing Security Technology Development Co., Ltd. 2004
3 35KV Substation Design Atlas Li Wendong 1998
Programmable Logic Controller (PLC) is a new industrial control device with simple structure, comprehensive performance and high reliability. Its outstanding advantages are: easy to use, outstanding real-time features and powerful communication capabilities. In its small unit, it contains powerful functions that make it easy to perform complex control tasks independently or through a network distributed system. With a small investment, the most efficient automation system can be obtained in the industrial field. It is very popular, especially after the special module configuration, it can greatly expand its application area while maintaining the ease of use. The PLC is small in size, compact in structure and convenient in programming. The ladder diagram programming method is oriented to general electrical technicians. It is easy to operate, easy to maintain, and easy to realize mechatronics. Therefore, it has been widely used in substation integrated automation.
The automation equipment in the integrated automation of small and medium-sized substation includes: programmable automatic monitoring device, programmable transformer automation screen, programmable microcomputer metering screen, programmable microcomputer line protection screen, programmable microcomputer synchronization system, programmable central signal screen, programmable capacitor The screen and programmable microcomputer DC power supply system all use PLC as their intelligent unit, and they can all run on the network to easily realize remote signaling, telemetry and remote control functions, replacing the traditional RTU. This paper mainly introduces the realization of transformer automation part composed of PLC in automatic substation. It is suitable for the automation transformation of old substations and the construction of new substations.
2 Transformer automation composition
In small and medium-sized substations, a transformer and its supporting equipment generally include: circuit breakers and operating units, transformers, transformer control panels, lightning arresters, differential protection screens, transformer grounding systems, etc. The following describes the automation configuration of the transformer in two cases.
2.1 Transformers and ancillary equipment are conventional equipment
If the circuit breaker and operating unit, transformer, differential protection screen, transformer lightning protection grounding system, etc. are all conventional equipment without intelligent unit and computer interface, then only the transformer control panel part should be selected as programmable (PLC) transformer automation. The screen can form a relatively complete transformer automation system. The system block diagram is shown in Figure 1. The transformer control panel and its supporting equipment in the central control room of the substation are directly connected with the programmable transformer automation screen through the cable for information exchange. The main computer monitoring system in the central control room or remote control monitors the transformer through the monitoring of the programmable transformer automation screen. The information exchange is controlled by the industrial computer (IPC) in the main computer monitoring system and the PLC in the programmable transformer automation screen. It is realized through an industrial field communication network. This kind of transformer automation system is generally suitable for retrofitting old stations or building new stations with small capital.
2.2 Transformers and ancillary equipment are intelligent equipment
If the circuit breaker and the operating unit, the transformer, the differential protection screen, and the lightning protection grounding system of the transformer all contain the intelligent unit and the computer interface, then the transformer control panel part adopts the programmable (PLC) transformer automation screen, which can be very convenient. Form a powerful transformer automation system. The system block diagram is shown in Figure 2. The transformer control panel and its supporting equipment in the central control room of the substation are exchanged with the programmable transformer automation screen through the industrial field communication network and the central control room or the remote host computer monitoring system. The programmable transformer automation screen has only a very small number of cable connections to the transformers and associated equipment. The whole system is very simple.
3 The composition and implementation of programmable transformer automation screen
The hardware equipment of the programmable transformer automation screen generally includes: PLC, PLC input/output signal isolation relay, near-ground operation button and fault alarm indicator, alarm, intelligent transformer oil temperature inspection instrument, intelligent signal test, small DC power supply , communication adapters, etc. The software mainly consists of PLC automatic monitoring program and communication program with monitoring host computer (host computer).
3.1 PLC selection
From the electrical characteristics of the above-mentioned controlled object (transformer), this system almost monitors the amount of switching. The temperature analog quantity and the signal analog quantity are all monitored by smart meters. The output contact switch quantity of the intelligent meter enters the PLC. Therefore, the PLC only needs to select the basic module and the communication module without special modules. Next, determine the number of PLC input ∕ output points, and count the number of monitoring points of the programmable transformer automation screen on the transformer and associated equipment. The general input does not exceed 64 points and the output does not exceed 40 points. In practice, we selected the Rock series PLC products developed by Beijing Ankong Technology Development Co., Ltd.: Rock E20 series PLC products. This product adopts advanced 16-bit CPU and is equipped with embedded real-time multi-tasking operating system. It can realize functions of acquisition, calculation, logic, timing, control and communication. Its single CPU+ expansion module can carry 32 modules and control 500 I∕. O point. Local expansion with RS485 or Intranet, remote expansion with dial-up Modem or GPRS. The product adopts the plug-in method to expand, the module size is small, the installation and use are convenient, the maintenance is simple, and the application is flexible, safe and reliable.
3.2 Programmable Transformer Automation Screen Hardware
The components that make up the programmable transformer automation screen should be designed and connected in strict accordance with the electrical specifications. In addition, the part connected to the PLC should be designed and connected in strict accordance with the technical requirements of the PLC manufacturer.
3.3 PLC automatic monitoring program
The different transformer composition of the substation determines the difference of the monitoring program of the programmable transformer automation screen PLC. Here, a 35KV single bus and a main transformer are taken as an example.
3.4 Realization of serial communication between PLC and monitoring host computer
4 programmable transformer automation screen operation
The programmable transformer automation screen is in an important position for real-time monitoring in the automatic operation of the transformer. It passes the input ∕ output signal isolation relay according to the substation substation equipment (isolated knife gate, circuit breaker, voltage transformer, current transformer, transformer lightning protection). Status of equipment such as grounding system ∕ Control signal, programmable logic controller (PLC) controls the above signals in real time according to the specific automation process, and transmits data to the monitoring host computer through the network. Complete the opening and closing of the transformer, operation and maintenance and relay protection (overcurrent protection, current quick-break protection, differential protection, gas protection and overload protection, etc.). It not only makes the transformer in the closed-loop automatic control, but also makes the transformer automation and the monitoring and control protection system work in coordination, so that the whole transformer is in optimal operation. Due to the characteristics of the PLC itself, each input ∕ output signal has an indicator light, making it extremely easy to maintain and repair the substation where the signal is scattered.
5 Conclusion
This system has been successfully put into operation in the automation engineering of several transformers in our city. We found that it is very easy to handle faults, which shortens the power outage maintenance time and the operation and maintenance costs are very low. In the operation, faults such as the water relay of the gas relay of the transformer, the disconnection of the electrical contacts of the contactor in the central control room, and the control circuit of the transformer can be found, alarmed and automatically entered into the processing program, and can be monitored on the host computer. Centralized monitoring. The application environment composed of PLC can be configured to meet the needs of different users or the same user in different periods. To change the organization of the system, it is only necessary to re-enter the PLC monitoring program. We are quite satisfied with this.
references:
1 Yang Shiyuan programmable controller programming application and maintenance 1995 Tsinghua University Press
2 Rock E20 Series PLC Products Beijing Security Technology Development Co., Ltd. 2004
3 35KV Substation Design Atlas Li Wendong 1998
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