Substation Automation System Status and Problems

Introduction: Substation automation has been one of the hot spots in China's power industry since the 1990s. It is not only the need for power construction but also the needs of the market. The number of substations in China grows at a rate of 3% to 5% each year, and thousands of newly-built substations are put into operation every year. At the same time, according to the requirements of the power grid, many substations are being carried out every year. Technological transformation to improve the level of automation. In recent years, China's substation automation technology, whether introduced from abroad or domestically developed and developed, has achieved significant development in terms of technology and quantity.
However, in actual engineering, some substation automation systems cannot fully function, there are many problems, and the defect rate is high, and it is impossible to realize real unattended operation and normal operation.

1. What is Substation Automation System Currently, computer technology is widely used in all walks of life. The development of software and hardware level has also brought a revolution to the secondary monitoring and control system of substations. From a technical point of view, substation automation technology is also a product of computer technology development. With the continuous improvement of microcomputer remote control technology and the continuous development of functions and the emergence of distributed RTU, the substation automation system has already reached the stage of history.

On the "Substation Automation System" (Substation Automation System-SAS) of the term, the International Electrotechnical Commission interpretation "provides automation systems including communications infrastructure, including in the substation (The SAS provides Automation Substationin cluding the Communication infrastructure)" is. In China, what we call substation automation system includes traditional automatic monitoring systems, relay protection, automatic devices, etc. It is integrated with functions such as protection, measurement, control, and remote transmission. It is realized through digital communication and network technology. A set of computerized secondary devices and systems for information sharing. It eliminates conventional control equipment such as control screens and meters, thus saving control cables and reducing the control room area.

Substation automation includes the collection of electrical quantities and the monitoring, control and regulation of the status of electrical equipment (such as circuit breakers), monitoring and operation of substations in normal operation, ensuring the normal operation and safety of substations, and collecting transients in the event of an accident. Electric quantity, implementation of monitoring and control, rapid removal of faults (completed by relay protection, fault recording, etc.), completion of the operation of the substation to restore normal operation after the accident; from a long-term perspective, it should also include the high voltage electrical equipment itself. Monitoring information (such as insulation and status monitoring of circuit breakers, transformers, arresters, etc.).

The secondary circuit of the traditional substation is composed of various types of devices such as relay protection, local monitoring, remote control, fault recording and ranging, DC system and insulation monitoring and communication. In the past, each of them used a separate device to complete. Its own function and self-contained system, which inevitably produced a function of mutual coverage between various types of devices, parts repeat configuration, consume a large number of cables and cables.

With the application of computer technology, network technology and communication technology, according to the actual conditions of substations, all types of distributed distributed substation automation systems will install the various field input and output unit components in the vicinity of the low-voltage circuit breaker cabinet or high-voltage primary equipment. The unit part or the two-in-one device of the protection and monitoring function is used to handle the protection and monitoring functions of each switch unit, or to keep the microcomputer protection and monitoring components of the site relatively independent. Disposed in the substation control room computer system, each cell-site communication contact member, generally serial communication port, such as RS-232C, RS-422/485 and LonWorks (Local Operation Network) or CAN (Control Area Network), etc. Fieldbus network technology.

The function of substation automation is to collect telemetering and remote communication, and to perform remote command execution and relay protection functions through the on-site unit components. These information are communicated through the network and the remote communication control unit and background computer system, thus completing the Traditional RTU and substation local integrated system functions. Therefore, in the modern substation automation system, the "protection" and "automation" expertise and equipment boundaries have changed.

2. Current status of substation integrated automation systems and existing problems 2.1 Technical standard issues of substation automation systems At present, there is no uniform standard for the design of substation automation systems. Standard issues of substation automation systems (including technical standards, automation system models, and management standards) Such issues are urgently needed to be solved.

2.1.1 Problems with Manufacturers Currently, in the selection of substation automation systems, there are problems such as the incompleteness of the functions of the selected system, the inadequacy of product quality, and the inability of the system performance indicators to meet the following requirements:

a. Due to the immature market economic system in China, manufacturers overemphasize economic interests. Users excessively pursue technological content and do not attach importance to the product's performance and practicality. As a result, although a number of technical contents are high, the products are not closed, even the structure is reliable. The so-called high-tech products with poor performance can still be used continuously. As long as some manufacturers buy, the enthusiasm for improvement is not high, and even some products lack the minimum quality assurance measures in the production process, and some of the purchased parts are also lack of management, resulting in some problems in substations that are put into operation;

b. Some manufacturers only organize technical appraisal for a certain product, and do not engage in product appraisal;

c. In addition, the manufacturer’s propaganda and introduction of the functions, roles, structure, and various technical performance indicators of the substation automation system are insufficient, resulting in the internal knowledge of the power company’s internal professionals being impervious to the system and resulting in more design flaws.

2.1.2 Interface problems of different products The interface is one of the most important and long-standing problems in automation systems, including RTU and communication controllers, protection and communication controllers, low-current grounding devices and communication controllers. Communication between fault recorder and communication controller, reactive device and communication controller, communication controller and master station, communication controller and analog disk. The products of these different manufacturers need to communicate with each other in terms of data interfaces. It takes a great deal of effort for software personnel to coordinate data formats, communication protocols, and other issues. When the products and types of different manufacturers are many, the problem is very serious.

If the data interfaces of the automation products of all manufacturers follow a unified and open data interface standard, the above problems can be satisfactorily resolved. Users can select according to the characteristics of various products to meet their own requirements.

2.1.3 Anti-interference problems of substation automation systems The anti-jamming problem of substation automation systems, also known as electromagnetic compatibility issues, is a very important but often neglected aspect. Traditional substation automation equipment factory anti-jamming test method is quite original, only to do some qualitative tests of the switch welder, fan, mobile phone, etc., often only plus the test of opening and closing the circuit breaker after the scene, has not been a quantitative Indicators, this is a great hidden danger.

The anti-jamming measures of the substation automation system are the basis for guaranteeing the reliable and stable operation of the substation automation system. When selecting, it should be noted that qualified substation automation products, besides satisfying the general inspection items, should mainly pass the high-low temperature test, damp-heat resistance test, and lightning. Impulse voltage test, dynamic test, but also focus on four electromagnetic compatibility tests, namely: 1MHz pulse interference test; electrostatic discharge interference test; radiation electromagnetic field interference test; fast transient interference test.

2.1.4 Transmission Protocols of Substation Automation Systems and Selection of Transmission Networks To realize the standardization of substation automation systems, it is necessary to achieve the standardization of transmission protocols and the standardization of transmission networks, so that the transmission protocol and the network can be unified, and the realization of substation automation systems can be realized. The interchangeability of equipment is very beneficial to both manufacturers and users. It is also very important for the development of substation automation technology. Therefore, in order to adapt to the development of this situation, IEC has gradually proposed a technical standard for transmission protocols.

a. The transmission protocol between substations and dispatch centers is not uniform at all parts of the country. Information transmission between substations and dispatch centers uses various forms of protocols, such as ministerial CDT, SC-1801, and DNP3.0.

In 1995, the IEC promulgated the IEC 60870-5-101 transmission protocol for the purpose of achieving compatibility between compatible devices. In order to enable China to adopt the international standards of motion transmission as soon as possible, the Ministry of Electricity issued the domestic version of the International 101 Statute in 1997. DL/T634-1997 was released at the Guilin Conference in 1998. This regulation sets a standard for the information transmission between the dispatcher and the station. In the future, the station-side substation automation equipment and the remote dispatching protocol should use the 101 protocol.

b. Communication protocols of the local area network At present, many manufacturers are acting on their own, causing difficulties in the communication connection between equipments of different manufacturers and hidden dangers of future maintenance.

In 1997, the IEC promulgated the IEC 60870-5-103 Statute. The State Economic and Trade Commission issued the domestic version DL/T667-1999 of the International Regulations 103 in 1999 and was published at the Nanchang Conference in 2000. The 103 regulation is approximately relay protection. The data communication transmission between the IED equipment and the substation layer equipment stipulates the standards. In the future, the substation automation system site protocol requires the 103 protocol.

c. Power metering transmission protocol of the power system For the power metering collection and transmission system, the IEC 60870-5-102 standard promulgated by the IEC in 1996, which is China's power industry standard DL/T719-2000, is needed when implementing the substation energy metering system. Obeyed.

The three standards mentioned above, commonly known as the 101, 102, and 103 protocols, apply to the three-layer reference model (EPA), namely the physical layer, link layer, and application layer architecture. It is the development of substation automation technology for quite some time. Three important criteria. These international standards are formulated according to the need for unbalanced and balanced transmission of motion information. They can fully satisfy various network topologies in power systems and will be widely used.

The IECTC57 is about to formulate a seamless telecontrol communication architecture, and has an open application and a unified network transmission protocol IEC61850. This agreement will be the only communication protocol between the substation (RTU or substation automation system) to the control center and the only communication protocol for the substation automation system or even the control center. At present, the standards used by various companies are not uniform, and the system interconnection and interoperability are poor. Therefore, the issue of transmission protocols should be considered in the construction of substation automation systems and equipment selection. That is, the 101 statute should be used between substations and control centers in substations. The internal protocol 103 should be used. The electricity energy metering and billing system should use the 102 protocol. After the new international standard IEC 61850 is issued, the substation automation system will use a unified communication protocol from the process layer to the control center.
2.1.5 The openness of substation automation system The substation automation system should be able to realize the interoperability (interchangeability) of the equipment produced by different manufacturers; the substation automation system should be able to accommodate the new development requirements of the substation automation technology; the substation automation system must be considered And support for substation operation function requirements. However, existing substation automation systems cannot meet such requirements. The interface between devices of various manufacturers is difficult or even impossible to connect. As a result, each manufacturer is going its own way, repeated development, and a lot of financial and material resources are wasted.

In addition, various screens and devices are not organized in the same way, which brings many problems for maintenance and management.

In our existing integrated automation equipment, there are a large number of manufacturers. Each series of products from different plants causes product models to be complex, spare parts are difficult to achieve, and equipment operation rate is low.

2.2 The problem of the choice of organization mode of substation automation system The substation automation system realizes the plan with the substation size, complexity, the important position of the substation in the power system, the required reliability, and the data flow rate of the substation and process layer bus. Different and change. If the mode of a substation automation system is properly selected, it can not only save investment and save materials, but also has high reliability and reliability due to its complete system functions and high quality. Therefore, the choice of a good substation automation system is of great significance.

At present, the most widely used substation automation system has three types: centralized, decentralized and centralized, and fully decentralized. The characteristics of the three structural types are briefly described below.

2.2.1 Centralized centralized substation automation system refers to the use of computers of different grades to expand its peripheral interface circuits, collect information on the analog, digital and digital quantities of substations centrally, and perform calculations and processing in a centralized manner to complete the microcomputers separately. Control, microcomputer protection and some automatic control functions. This kind of system is compact in structure, small in size, can reduce the floor space, the construction cost is low, apply to the substation of 35kV or smaller, but the operation reliability is poor, the configuration is not flexible.

2.2.2 Integration of Decentralization and Concentration The substation automation system combined with decentralization and concentration is to disperse the protection and measurement and control units of distribution lines in the switchgear cabinet, and the system structure of the centralized group screen is adopted for high-voltage lines and main transformer protection devices. . This structure is more commonly used, it has the following characteristics:

a, 10 ~ 35kV feeder protection using a decentralized structure, on-site installation, control cables can be saved, through the field bus and protection management machine exchange information.

b. High-voltage line protection and transformer protection adopt a centralized group screen structure. The protection screen is installed in the control room or protection room. Communication with the protection management machine through the field bus also makes these important protection devices in a relatively good working environment. Sex is more favorable.

c. In other automatic devices, the standby power supply self-investment control device and the voltage and reactive power integrated control device adopt a centralized group screen structure and are installed in a control room or a protection room.

2.2.3 Full decentralized, fully decentralized substation automation is a primary device such as switches, transformers, busbars, etc., as the installation unit, and the control, I/O, latching, protection and other units are dispersed and installed on the primary device screen. (Cabinet) on. The station control unit is connected to each primary device through the serial port and communicates with the manager and the remote dispatch center. It has the following features:

a. The configuration of the secondary part of the substation is simplified, and the area of ​​the control room is greatly reduced.

b. Reduced construction and equipment installation engineering. Since the protection and measurement and control unit installed in the switchgear was installed and commissioned by the factory before the switchgear was shipped from the factory, the number of cables laid was greatly reduced, so the on-site construction, installation and commissioning period was shortened.

c. It simplifies the interconnection between the secondary devices of the substation and saves a large number of connection cables.

d. The fully decentralized structure has high reliability, flexible configuration, convenient overhaul, strong anti-interference ability and high reliability.

The introduction of the above three kinds of substation automation systems, although time-sequential, but there is no situation before and after the replacement, the choice of substation structure should be based on the characteristics of various systems and the actual situation of substations, to be selected. For example, an RTU-based substation automation system can be used for the automation of existing substations. Decentralized substation automation systems are more suitable for new substations.

Due to the rapid development of microprocessors and communication technologies, the technical level of substation automation systems has been greatly improved, the structural system has been continuously improved, and the emergence of fully decentralized automation systems has provided a broader choice for the selection of substation automation systems. room. With the increase in the use of substation automation systems, whether it is a new construction, expansion or technical upgrading projects, the selection of substation automation systems should strictly comply with the selection requirements and strive to achieve standardized selection. The selected substation automation system not only needs advanced technology, complete functions, high performance-to-price ratio, system scalability and applicability, but also requires the manufacturer to have a considerable technical strength, a certain operating performance and a complete quality assurance system. After-sales service system.

2.3 The relationship between the current power management system and the substation automation system The construction of the substation automation system makes the professional protection of relay protection, remote control, measurement, and transformer operation infiltrate each other. The traditional technology division and professional management can no longer adapt to the integrated automation of substations. With the development of technology, although the substation remote control and protection professional has a clear division of professional equipment, its internal connection has become an integral whole. Once there are equipment defects, two specialties are required to arrive at the site for inspection and analysis, and sometimes there will be some irresponsibility. The situation has caused a huge waste of human resources, and many of the problems in the convergence of the two professions have become "two areas of nowhere" and are not conducive to carrying out work.

In terms of professional management, the operation, maintenance, and inspection of integrated automation substation equipment, especially the real-time nature of telecontrol systems, telemetering accuracy, speed of remote signaling displacement, signal return, and total signal of accidents, still need to be standardized and strengthened; Drive test and the implementation of the channel joint test, software data backup and other issues raised new topics.

2.4 The problem of low levels of operation and maintenance personnel While solving the existing problems of the substation automation system management system and technical standards, we must also train a group of high-quality professional teams.

At present, the maintenance of most equipments in substation automation systems depends on manufacturers. There are almost no professional teams in professional management, and when equipment defects are discovered, the corresponding manufacturers are notified to deal with them, which results in a series of problems such as inaccurate processing of defects.

In order to maintain and manage the substation automation system, we must first establish a professional team, train a group of interdisciplinary talents, and broaden the understanding and learning between relevant professionals.

Secondly, the division of substation automation majors should be clarified as soon as possible, and eliminate the phenomenon that “everybody controls and no one cares” for each grass-roots unit. The specialization of substation automation is of great significance for strengthening the level of grid management and preventing grid accidents.

3. Concluding remarks In recent years, the rapid development of communication technology and computer technology has injected new vitality into the improvement of the level of integrated automation technology in substations. Substation integrated automation technology is moving in the direction of networking, comprehensive intelligence, and multimedia.

In view of the current lack of a unified national standard for substation automation systems, it is necessary for the relevant power workers in each post to constantly sum up experience in the actual operation process, find their regularity, and not follow the old rules, but should follow the specific conditions. Scientific and rigorous work principles are used to develop the substation automation system with a vision of development to ensure safe, economical and high-quality operation of the power grid.

Fans & Fan Motors

Maidi Heating And Refrigerating Equipment Co., Ltd. ,