Intelligent substation can be regarded as adopting advanced, reliable, integrated, low-carbon and environmental protection intelligent equipment, taking the whole station information digitization, communication platform networking and information sharing standardization as the basic requirements, automatically completing the basic functions of information collection, measurement, control, protection, measurement and monitoring, and supporting the power grid real-time automatic control, intelligent regulation and online distribution according to the needs Analysis of decision-making, collaborative interaction and other advanced functions of the substation.
Substation is an important node of power grid transmission and distribution, which is the link of power generation, transmission and distribution. Substation covers a large number of primary and secondary equipment of power system, which is the basis of forming a strong grid structure of power system. Therefore, the construction of smart grid needs to strengthen the construction of Smart Substation. The construction of Smart Substation should be based on advanced information and automation technology, which can flexibly, efficiently and reliably meet the requirements of power generation, transmission and distribution on the grid, To achieve the goal of improving the security, reliability, flexibility and resource allocation level of power grid. However, the development of smart substation has just started, and the relevant national standards and specifications are still in the unified development stage. In order to achieve the construction goal of smart substation, comprehensively improve the intelligent level of substation, and improve the self diagnosis ability of intelligent equipment, it is necessary to conduct in-depth research on its key technologies.
1、 The concept of smart grid
In 2005, Ebel invented a technology and a wireless controller to coordinate building appliances by using the principle of group behavior. Smart grid began to appear at this time. Smart grid, also known as “future power grid”, is not a thing or thing, but a new modern power grid integrating some advanced technologies and power grid infrastructure. It has the characteristics of “more reliable, safe and economic, efficient, and more environment-friendly”. Its key technologies cover a wide range of fields, including sensor measurement technology, analysis and decision-making technology, brake control technology, and computing technology Machine technology and so on. In order to have a clear understanding of smart grid, we need to analyze its concept, connotation and characteristics, key technologies, intelligence and other aspects.
2、 Connotation and characteristics of smart grid
Based on market, environment, security and other factors, smart grid has eight characteristics: self-healing, compatibility, interaction, coordination, high efficiency, high quality, integration and green. Among them, self-healing means that in the aspect of power supply, smart grid can continuously find existing or potential problems, then correct or control them, and finally ensure the quality of power supply, which is reliable, safe and efficient. Interaction refers to “interaction”. In order to adapt to each other, smart grid can realize “two-way exchange and two-way communication”, and users can specify their own solutions in the information provided according to the actual situation. Many advanced technologies and monitoring technologies are applied in smart grid, which can better reduce costs and increase benefits, and achieve high efficiency. “Green” is another prominent feature. Smart grid can reduce environmental pollution and alleviate the huge problem of energy consumption by using green energy, clean energy and renewable energy. At the same time, it can alleviate the imbalance of regional energy supply.
In addition, smart grid is more suitable for computer and automation production requirements, and can support local innovation and national transactions.
3、 Construction principle
3.1 fully reflect the concept of digital design
3.11 intellectualization of primary equipment and networking of secondary equipment.
3.12 reduce the overall design, construction and operation cost of the substation.
3.2 the intellectualization of primary equipment is mainly reflected in the application of electronic transformer and intelligent circuit breaker.
3.21 effectively reduce the substation floor area and Electromagnetic CT saturation problems.
3.22 using combiner to solve the problem of repeated investment in data acquisition equipment.
3.23 using network to replace secondary cable can effectively solve the problem of AC / DC crosstalk of secondary cable and simplify the construction.
3.24 open circuit breaker: i2t monitoring of arc extinguishing energy, temperature measurement of isolating switch, online five prevention interlocking.
3.25 condition monitoring of main transformer
3.3 the networking of secondary equipment is mainly reflected in the three layers and two networks of the system structure.
3.31 station control layer, bay layer and process layer.
3.32 station control layer and bay layer focus on interconnection and Interoperability Based on IEC61850 standard to realize data sharing.
3.33 the primary design principle of process layer is reliability and stability.
3.4 advanced application: intensive, networked and intelligent automation function.
3.41 protection measurement and control integration optimization.
3.42 online integrated five prevention.
3.43 programmed control and system interlocking.
3.44 equipment condition monitoring and maintenance
3.45 accident abnormal expert analysis system
3.46 intelligent detection and control (Internet of things)
3.47 unmanned inspection support platform
4、 Technical principles of Smart Substation
4.1 intelligent equipment of Intelligent Substation
4.11 has the main technical features of information digitization, function integration, compact structure and state visualization.
4.12 meet the industrial application requirements of easy expansion, easy upgrading, easy transformation and easy maintenance.
4.2 design and construction of intelligent substation.
4.21 according to the requirements of DL / t1092.
4.22 meet DL / t755 level III Safety and stability standards.
4.23 meet the requirements of GB / t14285 relay protection for selective quick action, sensitivity and reliability.
4.3 the measurement, control and protection devices of intelligent substation shall meet the relevant requirements of GB / t14285, DL / t769, DL / t478 and GB / t13729, and the background monitoring function shall refer to the relevant requirements of DL / t5149.
4.4 the communication network and system of intelligent substation shall comply with DL / T860 standard.
5、 Advantages of Smart Substation in today’s power grid
Smart substation is an important part of smart grid. The development focus of substation is smart substation, which will play a pioneering role in the construction of smart grid.
The main advantages of smart substation are as follows:
Optical fiber instead of cable, design, installation and debugging become simple
The analog input circuit and the switch input and output circuit are replaced by the communication network, and the hardware system of the secondary equipment is greatly simplified? Unified information model avoids protocol conversion and information can be fully shared? Enhanced observability and controllability, resulting in new applications: such as condition monitoring, station area protection and control, mainly reflected in the following aspects: the introduction of electronic transformers, merging unit intelligent terminals, switches and other new devices; the adoption of IEC61850 standard, IEEE1588 new standard; its relay protection system, communication network structure; and the development of some new functions.
The essential advantages of intelligent substation are as follows: Digitalization of process equipment, mainly electronic transformer / merging unit and intelligent terminal; networking of information transmission, mainly IEC61850 standard and network communication technology.
6、 Concluding remarks
The intelligent condition monitoring technology of substation equipment is still in its infancy. According to its current situation and characteristics, the following suggestions are put forward
(1) The mature monitoring technology is introduced into the primary equipment of power grid to improve the monitoring effectiveness and accuracy of intelligent primary equipment. Intelligent primary equipment has become a clear development direction. Only by further improving the practicability of intelligent primary equipment, can it ensure its benign development.
(2) Promote the integration of intelligent primary equipment condition monitoring technology and traditional secondary technology, and truly realize the integration of five functions of measurement, calculation, control, inspection and maintenance, with smooth information sharing, good function integration and reliable operation.
(3) The comprehensive analysis system of intelligent primary equipment is further developed to realize the advanced application functions of condition evaluation, life prediction and fault diagnosis. The comprehensive evaluation results of intelligent components are basically consistent with the evaluation results of professional and technical personnel, and the intelligent level is significantly improved.
(4) Strengthen the detection and verification of intelligent equipment into the network. Intelligent equipment is still in the development stage, and its products are not mature. Only by establishing and improving the network access detection and verification work, and systematizing, normalizing, standardizing and professionalizing the work, can the product quality be guaranteed and the intelligent level of primary equipment be effectively improved.