The Development History of Smart Substation! Introduction of Key Technologies of Smart Substation

The smart substation adopts reliable, economical, integrated, low-carbon, and environmentally-friendly equipment and design, with digitalization of station information, networking of communication platform, standardization of information sharing, integration of system functions, compact structure design, intelligentization of high-voltage equipment and operation status Visualization is the basic requirement, and it can support real-time online analysis and control decision-making of the power grid, thereby improving the reliability and economical operation of the entire power grid. Automatically complete basic functions such as information collection, measurement, control, protection, metering, and detection. At the same time, it is a substation with advanced functions such as supporting real-time automatic control of the power grid, intelligent adjustment, online analysis and decision-making, and collaborative interaction.

1. Introduction of smart substation

Smart substation mainly includes two parts: intelligent high-voltage equipment and substation unified information platform. Intelligent high-voltage equipment mainly includes intelligent transformers, intelligent high-voltage switchgear, electronic transformers, etc. The intelligent transformer is connected with the control system by means of communication optical fiber, so that the status parameters and operating data of the transformer can be grasped in time. When the operation mode changes, the device decides whether to adjust the tap according to the voltage and power of the system; when there is a problem with the device, it will issue an early warning and provide status parameters, etc., to a certain extent reduce operation management costs, reduce hidden dangers, and improve Transformer operational reliability. Intelligent high-voltage switchgear is switchgear and control equipment with high performance, equipped with electronic equipment, sensors and actuators, and has monitoring and diagnostic functions. Electronic transformers refer to pure optical fiber transformers, magneto-optical glass transformers, etc., which can effectively overcome the shortcomings of traditional electromagnetic transformers. There are two functions of the substation unified information platform. One is the horizontal information sharing of the system, which is mainly manifested in the unification of information obtained by various upper-level applications in the management system; the other is the standardization of vertical information in the system, which is mainly manifested in the Support transparency.

Intelligence means humanization, which is to make the substation as if it is adjusted by a human. When the low-voltage load increases, the substation sends out enough power to meet the increased load. When the low-voltage load decreases, the substation sends out less power to ensure energy saving.

2. Development prospect of smart substation

Smart grid construction is based on the characteristics of my country's energy distribution and regional distribution of load consumption, and adapts to the grid development mode adopted by my country's current and future social development. It has strong adaptability to the input and delivery of various energy sources, especially large-scale wind power and solar power generation. , can realize large-scale and high-efficiency allocation of energy resources. The construction of my country's smart grid has risen to the level of national strategy. Smart substation is one of the core platforms to realize energy conversion and control in the construction of a strong smart grid, and the prospect is still bright.

The development prospects of smart substations are still broad. According to the National Smart Grid "Twelfth Five-Year Plan", by 2015, there will be about 5,182 new smart substations, including about 19 new 750 kV smart substations, about 182 500 kV smart substations, and about 60 330 kV smart substations. 1,198 220 kV smart substations, 3,710 110 (66) kV smart substations; 64 500 kV, 18 330 kV, 320 220 kV, 630 110 (66) kV substations substation.

It is estimated that during the "Twelfth Five-Year Plan" period, the investment in the intelligent part of the new smart substation is about 53.76 billion yuan, and the total investment in the intelligent transformation of the substation is 9.38 billion yuan. During the "Twelfth Five-Year Plan" period, the overall investment in the smart grid construction plan is 1.6 trillion yuan. According to the calculation of about 20% of the smart substation link, the investment in the smart substation link will reach 320 billion yuan, and the prospect is still broad.

Photovoltaic power generation is random, intermittent and volatile, which limits its grid-connected capacity to a certain extent, which limits the large-scale application of photovoltaic power generation to a certain extent. The development of smart grid has promoted the initiative of all parties in the society to use photovoltaic power generation, and improved the development and use efficiency of photovoltaic power generation.

My country's research on smart grid has also been going on. At present, the domestic power grid cannot meet the development needs of the photovoltaic power generation industry, so my country will build a "strong smart grid" with "UHV as the core" to solve the problem of photovoltaic power generation grid integration and promote the utilization of new energy.

My country's smart grid is based on a strong grid with UHV grid as the backbone grid and coordinated development of grids at all levels, using advanced communication, information and control technologies. Build a unified, strong and intelligent power grid characterized by informatization, automation, digitization, and interaction.

All countries in the world have invested a lot of money in research on smart grids and solar energy and other new energy power generation. This is because new energy power generation relies on the development of smart grids. The high-speed, reliable, economical and safe power transmission channel of the smart grid provides a good guarantee for the power transmission of photovoltaic power generation, and its development and application are complementary and mutually promoting.

3. Technical advantages of smart substation

3.1 Smart substation can achieve good low-carbon environmental protection effect
In smart substations, traditional cable wiring is no longer used in engineering, replaced by optical fiber cables, and a large number of electronic components with high integration and low power consumption are used in various electronic equipment. In addition, the traditional oil-filled mutual inductor The transformer did not escape the fate of being eliminated, and the electronic transformer replaced it. Whether it is the improvement of various equipment or wiring methods, it has effectively reduced energy consumption and waste, not only reduced costs, but also effectively reduced the damage caused by electromagnetic, radiation and other pollution inside the substation to people and the environment. It greatly improves the quality of the environment, realizes the optimization of the performance of the substation, and makes its ability to protect the environment more significant.

3.2 Smart substation has good interaction
The working characteristics and responsibilities of the smart substation make it necessary to have good interaction. It is responsible for the statistical work of grid operation, which requires him to have the function of feeding back safe, reliable, accurate and detailed information to the grid. After the smart substation realizes the information collection and analysis functions, it can not only share the information internally, but also interact well with more complex and advanced systems in the network. The interactive nature of the smart grid ensures the safe and stable operation of the grid.

3.3 Reliability characteristics of smart substation
One of the basic requirements of customers for electric energy is reliability. Smart substations have a high degree of reliability. While meeting customer needs, they also achieve high-quality operation of the power grid. Because the substation exists as a system, it is easy to lead to the whole body, so the substation itself and all the internal facilities have a high degree of reliability. Such characteristics also require the substation to have the function of detecting and managing faults. This function can effectively prevent the occurrence of substation faults, and can quickly deal with them after the fault occurs, so that the working conditions in the substation can always be kept in the best state.

4. Development direction of smart substation

As the development direction of the future power grid, the smart grid penetrates into every link of power generation, power transmission, power transformation, power distribution, power consumption, dispatching, and communication information. Among the above-mentioned links, the smart substation is undoubtedly the core link.

Smart substations evolved from digital substations. After four years of development, the technology has been perfected day by day. Compared with other links, smart substations have reached the conditions for large-scale promotion. The smart substation is mainly composed of the equipment layer and the system layer. The biggest difference from the traditional substation is reflected in three aspects: primary equipment intelligence, equipment maintenance state, and secondary equipment network.

After 2011, all newly-built substations will be fully constructed in accordance with the technical standards of intelligent substations, and the focus will be on intelligent transformation of hub and central substations. According to the plan of the State Grid, my country's smart substations will usher in explosive growth in the future: in the first stage, 46 new smart substations will be built, and 28 will be intelligently transformed in operational substations; 48 UHV AC substations were renovated; in the third phase, 7,700 smart substations were built, 44 substations in operation were intelligently renovated, and 60 UHV AC substations were renovated.

In September 2015, the first completed project of the 50 new-generation smart substation expansion demonstration projects of the State Grid Corporation of China - the first new-generation smart substation in Jiangxi Province - the 110 kV Ganxian Shuanglong substation was put into operation at 11:16 on September 29. electricity. It marks the official operation of China's new generation of smart substations.

According to the State Grid's "Twelfth Five-Year Plan" smart grid construction plan, in the early stage of the "Twelfth Five-Year Plan", the progress of new smart substations will maintain a rapid growth rate, and in the later stages, the proportion of smart substation renovations will gradually increase. As of the sixth batch of tenders in 2013, the bidding volume of smart substations has reached about 3,600, and the bidding volume is basically in line with planning expectations. However, the proportion of bidding in recent batches of smart substations has declined compared with the previous period. The operation effect of smart substations has not met expectations; the manufacturing cost of smart substations has been reduced slowly, and the cost is still high; State Grid is actively promoting new pilot projects for second-generation smart substations, which is expected to slow down the construction progress of existing smart substations and reduce the cost of smart substations. Tender ratio. As the new generation of smart substation pilot projects are gradually put into operation, the bidding ratio of smart substations will continue to increase, and the construction progress will continue to accelerate.

5. Technical characteristics of smart substation

5.1 Architecture
The intelligent substation system is divided into three layers: process layer, interval layer, and station control layer. The process layer includes intelligent equipment, merging units and intelligent terminals composed of primary equipment and intelligent components, and completes substation power distribution, conversion, transmission and related functions such as measurement, control, protection, metering, and status monitoring. According to the requirements of the relevant guidelines and specifications of the State Grid, the protection should be directly sampled, and the protection of a single bay should be tripped directly, and the protection involving multiple bays (busbar protection) should be tripped directly.

Smart components are flexible physical devices that can include one or more of measurement units, control units, protection units, metering units, and status monitoring units.

Bay layer equipment generally refers to secondary equipment such as relay protection devices, measurement and control devices, and fault recorders. device communication.

The station control layer includes subsystems such as automation system, station domain control system, communication system, and time synchronization system, which realize the measurement and control functions for the whole station or more than one sub-equipment, and complete data acquisition and monitoring control (SCA-DA), Operation blocking and synchrophasor acquisition, electric energy acquisition, protection information management and other related functions.

The functions of the station control layer should be highly integrated, and can be realized in one computer or embedded device, and can also be distributed among multiple computers or embedded devices.

5.2 Smart primary equipment
High-voltage equipment is the basic unit of the power grid, and the intelligence of high-voltage equipment (or smart equipment) is an important part of the smart grid, and it is also one of the main signs that distinguish the traditional power grid. The core task and goal of intelligent equipment is to use sensors to monitor the operating status of key equipment in real time, and then to realize the observability, controllability and automation of grid equipment. "Technical Conditions for Intelligentization of High-Voltage Switchgear" and "Technical Conditions for Intelligentization of Oil-immersed Power Transformers" have made relevant regulations on the intelligentization of sub-equipment. In the case of meeting the requirements of relevant standards, functional integration design can be carried out, including the following three aspects: ① Integrate the sensor or/,u actuator with high-voltage equipment or its components to achieve specific monitoring or/, u Control purposes; ② Integrate design of high-voltage equipment such as transformers, transformers, and circuit breakers to reduce the area occupied by substations; ③ In intelligent components, integrate related measurement, control, metering, monitoring, and protection into an integrated design , to achieve the integration of primary and secondary equipment.

5.3 Intelligent equipment and sequence control
To achieve intelligent high-voltage equipment operation, sequential control should be adopted to meet the requirements of unattended and regional monitoring central station management mode; it can receive control instructions issued by the execution monitoring center, dispatching center and local background system, and automatically after the safety check is correct. Complete equipment control that meets the requirements for changes in relevant operating modes, that is, it should be able to automatically generate typical operation tickets for different main wiring and different operating modes; automatically cast and withdraw the protective soft pressure plate; when there is an emergency defect in the equipment, it has an emergency stop function.

6. Key technologies of smart substations

6.1 Reference of distributed power in smart substation
The introduction of distributed power in smart substations can enhance the safety and flexibility of smart grids and significantly improve operating efficiency. In addition, the existence of a single power flow network in the power distribution system has also been changed, making it radiate from one-way power The network transformed into a multi-source network. The original protection measures and protection behaviors in the substation are all aimed at the single power flow network. Now the transformation of the single power flow network into a multi-type network will make the previous protection behavior and protection measures no longer safe and reliable. According to this transformation, access to distributed power generation poses greater challenges to the role of relay protection in smart substations.

6.2 Hardware integration technology in smart substation
With the continuous development and progress of the smart grid, the grid hardware system began to have hardware description language, and the appearance of hardware description language made the design and application of smart substations have the characteristics of integration, automation and modeling. The above features lead to a fully functional modular planning in the hardware system, which can solidify some different logic problems to the equipment inside the smart substation, and the control of the software reaches the application of the hardware. Therefore, the accuracy and reliability of the design and application are ensured, and the key problems in information transmission are also solved.

6.3 Component technology of software in smart substation
The software technology and hardware technology in intelligent substation complement each other, and the two form a perfect cooperation. The software system is the soul and key to ensure the normal operation of the smart substation. It can not only realize the information control and monitoring functions, but also integrate functions such as phasor measurement unit (PMU) and wave recording. control, online status monitoring, remote operation and other advanced functions. It is of far-reaching significance to ensure the safe and stable operation of increasingly large and complex power systems and to improve the degree of automation.

7. Survival advantages of smart substations

Smart substations are an important part of smart grids. The focus of development in the field of power transformation is smart substations. Smart substations will play a pioneering role in the construction of smart grids.

7.1 Main advantages of smart substations:
7.1.1 Optical fiber replaces cables, making design, installation and commissioning easier
7.1.2 The analog input circuit and the digital input and output circuit are replaced by the communication network, and the hardware system of the secondary equipment is greatly simplified
7.1.3 A unified information model avoids protocol conversion, and information can be fully shared
7.1.4 Observability and controllability are enhanced, resulting in new applications: such as condition monitoring, station domain protection control

It is mainly reflected in the following aspects: the introduction of new devices such as electronic transformers, merging unit intelligent terminals, and switches; the adoption of the IEC 61850 standard and the new IEEE1588 standard; among them, the relay protection system and communication network structure; some new features.

The essential advantages of smart substations are mainly reflected in: the digitization of process equipment, mainly electronic transformers/mergers, and smart terminals; the networking of information transmission, mainly IEC 61850 standards and network communication technologies.

7.2 The intelligent status monitoring technology of substation equipment is still in the initial stage of development. According to its current situation and characteristics, the following suggestions are made:

7.2.1 Introduce mature monitoring technology into the primary equipment of the power grid to improve the monitoring effectiveness and accuracy of smart primary equipment. Smart primary equipment has become a clear development direction, and only by further improving the practicability of smart primary equipment can its healthy development be guaranteed.

7.2.2 Promote the integration of intelligent primary equipment condition monitoring technology and traditional secondary technology, and truly realize the integration of the five functions of measurement, measurement, control, inspection, and maintenance. Its information sharing is smooth, its functions are well integrated, and its operation is reliable.

7.2.3 Further develop the comprehensive analysis system of intelligent primary equipment to realize the advanced application functions of status evaluation, life estimation and fault diagnosis. The comprehensive evaluation results of the equipment status of the smart components are basically consistent with the evaluation results of professional and technical personnel, and the level of intelligence is significantly improved.

7.2.4 Strengthen the detection and verification of smart devices connected to the network. Smart equipment is still in the development stage, and the products are immature. Only by establishing and improving the network access testing and verification work, and making this work systematic, normalized, standardized, and professional, can product quality be guaranteed and the level of intelligence of primary equipment can be effectively improved.