The design and communication solution of the integrated automation system of the substation. The
power system is a special system with high safety and reliability requirements. In order to realize the safe and reliable operation of the system, it is necessary to realize the automation of the dispatching, operation and management of the power system. With the improvement of power system automation, fieldbus technology is becoming more and more perfect, and power system downsizing and increasing efficiency requirements are proposed to realize the integrated automation of power stations, so as to achieve unattended operation, which has become the advantage of the development of power system automation. At present, the use of high-performance microcontrollers, fieldbus technology, real-time multi-task operating systems and other advanced technologies that conform to the direction of modern industrial control technology can realize comprehensive automation functions for medium and low voltage transmission and distribution lines and main equipment. Moreover, it can integrate protection, monitoring, control, and communication. It can be networked to form a comprehensive automation system, or it can run independently. It can be suitable for manned monitoring centers and unattended requirements. As everyone knows, the key to comprehensive automation of substations lies in the rapid and accurate upload of a large amount of on-site information and data to the monitoring center in real time. The control commands issued by the monitoring center can also be accurately and accurately sent to the control unit to take timely measures to avoid accidents. , This requires reliable communication guarantee for the integrated automation system of the substation. With the widespread application of fieldbus technology in power system automation, it effectively solves the communication problems in the integrated automation system of substations .
The composition of the integrated substation automation system The
integrated substation automation system generally consists of a computer monitoring system composed of a station control layer, a communication management layer and a bay layer. It adopts a distributed structure. The equipment is divided into a station control layer, a communication management layer and a bay layer. The principle of the bay layer is The above is organized according to the primary equipment. Each bay level equipment includes basic functions such as measurement, control, protection, signal, communication, and recording, and completes their own special functions. The system can realize the integration of information sharing and protection and monitoring functions. The secondary circuit is greatly simplified, and system investment is saved. Since the bay equipment can be placed near the switch cabinet or the primary equipment, the area of the main control room is greatly reduced, the control cable is saved, and the reliability and scalability of the entire system are greatly improved. Due to the diversity of the communication protocol of each bay layer equipment, the communication management layer can realize the data link of different devices by adding the front-end processor (communication management device) to complete the communication control and protocol conversion, so that it can realize the communication receiving, sending, Protocol conversion and other functions; the communication protocol adopts the power industry standard protocol, which can realize the interconnection of equipment from different manufacturers, adopts the global positioning system (GPS), supports the hardware time synchronization network, reduces the connection between the GPS and the equipment, and ensures the accuracy of time synchronization. Modular design is adopted to support a variety of communication interfaces, including Ethernet, serial communication interfaces, and other expandable fieldbus interfaces; the software has a protocol library to support RS-232, RS-485, LONWORKS and standard network protocols (TCP/IP) and other types of standard communication interfaces, which have good software and hardware scalability. The station control layer includes database server, Web server, operating workstation, maintenance workstation, monitoring workstation, etc.
Substation integrated automation system function
Taking a 110KV substation as an example, according to the overall requirements of the primary system of the substation high-voltage power supply system, the substation integrated automation system decided to adopt the CL2000 substation integrated automation system. Here, combined with engineering practice, introduce the system for the substation monitoring system Experience in.
The integrated automation system of the substation consists of WXH-322A/01 microcomputer line protection device, WBH-90 series microcomputer transformer protection device, ZBH-91A/05 transformer body protection device, WBH-92A/02 microcomputer transformer backup protection device, and WMC-31A03 microcomputer bus Differential protection device, WBH-93A/02 microcomputer factory power protection device, WBT-31A/01 microcomputer backup power automatic switching device, microcontroller SAB-C167CR (produced by SIEMENS), workstation computer and corresponding equipment. The CL2000 substation integrated automation system series protection device has general main functions, such as the remote control of the switch value, the analog input of voltage and current, the remote control of the circuit breaker, the pulse accumulation, the remote control event recording and sequence recording (SOE), logic blocking, etc. .
The microcomputer line protection device is a multi-CPU parallel design, distance protection, zero sequence protection and wave recording. The distance measurement is performed by a separate CPU. Each CPU plug-in is independent of each other in electrical and structure, and has no dependence. It can achieve the following functions:
( 1) Protection function: a) Three-stage phase-to-phase distance protection; b) Three-stage grounding distance protection; c) Four-stage zero-sequence direction overcurrent protection; d) Fault location; e) Oscillation blocking; f) Three-stage Type reverse and low-voltage blocking over-current protection; g) Three-phase one-time reclosing of no-voltage detection and synchronization detection, manual synchronous closing; h) Low-cycle low-voltage load shedding protection; i) Overload protection or alarm; j) PT off Line alarm.
(2) Measurement function: a) Collect and measure voltage, three-phase or two-phase measurement current, calculate active power and reactive power
Communication function realized by fieldbus technology
The communication function is one of the most obvious signs of comprehensive automation which is different from the conventional station. The interval information in the communication network substation can be fully shared, and information can be exchanged with the external information system through the communication interface. At the same time, it saves a lot of cables, forming a fast, stable and reliable The communication network is the basic requirement of the substation automation system and the basic premise of the power system operation management function.
In recent years, with the continuous development of my country's power automation, power system communication methods have also been continuously improved. Field bus technology has been widely used due to its convenient networking and strong anti-interference ability. There are many fieldbus standards, the most commonly used in power automation systems are LONWORKS and CAN bus.
The LONWORKS bus communication rate is 78Kbps and 1.25Mbps, and the CAN bus communication rate is 1Mbps. CAN bus is a serial communication network that effectively supports distributed control and real-time control. It is a multi-master bus with a communication rate of up to 1Mbps.
It has a priority preemption mechanism for bus arbitration, high communication rate, automatic retransmission of error frames, automatic isolation of permanent faults, without affecting the normal operation of the entire network, high reliability, simple protocol, strong openness, and flexible networking , Low cost and other characteristics, can provide open, fully distributed and interoperable communication platform for power automation.
The main features of CAN bus:
(1) CAN works in a multi-master mode. Any node on the network can actively send information to other nodes on the network at any time, regardless of primary and secondary. The communication method is flexible, and no node information such as station address is required. ;
(2) using the CAN short frame structure, data of up to 8 bytes, so that not only satisfies the control transfer control command field,
(. 3) using the CAN bus arbitration non-destructive technique, when a plurality of nodes simultaneously transmit information to the bus, Nodes with lower priority actively quit sending, while nodes with higher priority can continue to transmit data unaffected, thus greatly saving bus conflict time. The direct transmission distance of CAN is up to 10Km/ 5Kbps, and the communication rate is up to 1Mbps/40m. Up to 110 devices can be connected. The CAN node has an automatic shutdown function when an error occurs in itself, so that the operation of other nodes on the bus is not affected.
The bay layer of this system is mainly composed of protection unit and measurement and control unit. Each measurement and control unit monitors multiple feeds and feeds. It adopts advanced field bus CAN, field communication uses twisted pair, and the bus rate reaches 1 Mbps, which is fast, reliable, convenient and flexible. , The communication protocol supports the IEC-60870-5-101 format, which overcomes the defect that there can only be one master node on the RS485 network and cannot form a multiple redundant system, and has a high price ratio. In addition, the dual CAN fieldbus is used to periodically perform standby detection on the standby CAN, which improves the redundancy of the internal network.
The station control layer adopts a dual 10 Mbps twisted pair Ethernet structure (which can ensure the real-time transmission of the internal communication network of the substation automation system), and is composed of dual servers. The station control layer provides on-duty personnel with the monitoring, control and management functions of the whole plant system , Friendly interface and easy to use. Through the component technology, the software function can achieve "plug and play", which can better meet the needs of the electrical monitoring system. The software system adopts a modular structure and is open. The station control layer operating system can adopt Windows2000/NT, and the database adopts SQL server. The main function modules of the software include front-end, database generator, database configuration, report management, alarm information, curve, bar graph, action alarm, SOE, accident recall , Waveform analysis, man-machine interface, automatic meter reading, equipment management, fixed value management, equipment online diagnosis, system configuration, etc. The electrical monitoring system provides interface driver software such as fault information transmission system, dispatching centers at all levels, electric energy metering system, and DC system communication.
In short, the main functions completed by the system are: real-time data acquisition and processing, database establishment and maintenance, control operation, synchronization detection, alarm processing, sequential recording (SOE), accident recall, screen generation and display, online calculation and tabulation, Electric energy processing, remote control function, electrical "five defenses", clock synchronization, human-machine interface, system self-diagnosis and self-recovery, interface with other smart devices, operation management functions, etc.
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