0 Preface
The power grid is an important basic industry for economic and social development and an important link in the national energy industry chain. In order to ensure China's future energy and sustainable economic and social development, the State Grid Corporation has proposed a smart grid development model that meets China's energy strategy and the needs of power grid companies. Smart grid refers to the intelligence of the grid and is based on an integrated, high-speed two-way communication network. Through the application of advanced sensing and measurement technology, advanced equipment technology, advanced control methods, and advanced decision support system technology, the goal of reliable, safe, economical, efficient, environmentally friendly and safe use of the power grid is achieved. According to MarTIn Hauske, a senior power expert at IBM China, the smart grid has three levels of meaning [1]: First, use sensors to monitor the operating status of key equipment such as power generation, transmission, distribution, and power supply in real time; The data is collected and integrated through the network system; finally, through the analysis and mining of the data, the optimal management of the operation of the entire power system is achieved. At the "2009 UHV Transmission Technology International Conference" held on May 21, 2009, Liu Zhenya, General Manager of State Grid Corporation of China, said that the active development of smart grid has become a new trend in the development of the world ’s power. By 2020, China will be fully integrated Strong smart grid. China's State Grid has established the development goal of accelerating the construction of a strong smart grid based on the basic national conditions and UHV practice, that is, accelerating the construction of UHV power grid as the backbone grid, coordinated development of power grids at all levels, with informatization, digitization, automation and interaction Features a unified and strong smart grid.
In order to improve the safety and stability of the smart grid and the efficiency of the management of power grid equipment, it is necessary to strengthen and enhance the monitoring capabilities of power grid facilities. Effective methods and advanced technologies, sensing technologies, status assessment technologies, information technologies, and communication support for the status detection of transmission and transformation equipment Technology to carry out technical research and engineering applications. In July 2009, the State Grid Corporation of China decided to fully promote the implementation of state maintenance from 2010, comprehensively improve the level of equipment intelligence, promote the application of intelligent equipment and technology, and realize the online warning and intelligent monitoring of equipment safety.
1 Differences between smart grid and traditional grid in condition detection
1.1 Current status of traditional power grid status detection technology
Condition maintenance is based on the current actual working condition of the equipment. Through advanced condition monitoring methods, reliability evaluation methods and life prediction methods, the equipment status is judged, the early signs of the failure are identified, and the location and severity of the failure and the development trend of the failure are identified. Make judgments and perform maintenance before equipment performance drops to a certain level or failures will occur according to the analysis and diagnosis results [2]. The efficient development of state maintenance requires a large amount of equipment state information, which provides basic data for the evaluation of equipment state and the formulation of state maintenance strategies. Equipment status information includes inspection, operating conditions, live detection, power failure routine tests, power failure diagnostic test data, etc.
With the development of state detection technology, people more and more clearly realize that the trinity detection mode of "live detection, online monitoring, and power failure maintenance test" represents the future development direction of power transmission and transformation equipment state detection technology.
Live detection generally uses portable detection equipment, on-site detection of the state of the equipment in the running state, the detection method is live short-term detection, which is different from long-term continuous online monitoring [3]. In terms of live detection technology, the main live detection technologies currently used at home and abroad include: oil chromatography analysis, infrared temperature measurement, partial discharge detection, core current live detection, ultraviolet imaging detection, capacitive equipment insulation live detection, gas leak live detection, Among them, the most commonly used and most effective are partial discharge detection, oil chromatography analysis and infrared temperature measurement technology. Especially the partial discharge live detection technology, which is currently the most rapidly developed and the most effective one for the detection of electrical equipment insulation defects.
In terms of on-line monitoring technology, the current applications are mainly concentrated on substation equipment, and some applications are gradually appearing on transmission lines and cables. For substation equipment, the online monitoring technologies used in transformers and reactors mainly include: oil chromatography, partial discharge, core grounding current, bushing insulation, top layer oil temperature and winding hot spot temperature; capacitive devices such as CT, CVT, coupling capacitors are mainly Monitor its electrical capacity and dielectric loss; lightning arrester mainly monitors its leakage current; and the main online monitoring technologies of circuit breakers, GIS and other switching equipment include mechanical characteristics of the switch, GIS partial discharge, SF6 gas leakage and SF6 micro water and density. Among them, the applications are relatively mature and effective: on-line monitoring of transformer oil chromatography, on-line monitoring of capacitive equipment and arresters. For transmission lines, the main online monitoring methods currently used mainly include lightning monitoring, insulator contamination, tower tilt, and wire sag, but the more mature ones are mainly lightning monitoring and insulator contamination monitoring. For power cables, the main online detection methods are temperature and partial discharge, and the relatively mature one is distributed optical fiber temperature measurement.
In terms of power failure maintenance tests, a set of mature preventive test methods and procedures have been formed at home and abroad.
China's state detection and evaluation work is still in its infancy, and the main problems in the application and promotion of state detection technology are: (1) The application range of state detection technology is not wide. Compared with the total power grid equipment, the equipment coverage of state monitoring technology application It is still at a low level; (2) The reliability of the state detection device is not high, there are false alarms, and the failure rate of the device is high, and the workload of operation and maintenance is large; (3) The lack of unified standards and norms guidance, each manufacturer The working principle, performance index and operation reliability of the device are quite different. At the same time, the verification methods, output data specifications and monitoring platforms of various devices are different; (4) The lack of in-depth and effective comprehensive state assessment methods; (5 ) The online monitoring technology needs to be deepened. The current online monitoring technology still has blind spots in the detection of equipment defects, the status parameters are not rich enough, and the role of early warning of sudden failures is not obvious; (6) The lack of unified assessment, evaluation and guidance Industry management agency.
1.2 Differences in state detection between smart grid and traditional grid
The scope of the smart grid's acquisition of status information will change greatly from the traditional grid. In the future, the status information of the smart grid not only includes the status information of the grid equipment, such as the health status of the power generation and transmission and transformation equipment, and the economic operation curve; but also the real-time information of the grid operation, such as: the unit operating conditions, the grid operation Conditions, tide information, etc .; there should also be natural physical information, such as: geographic information, breath information, etc. [4].
The information acquisition and utilization level of the traditional power grid is low, and it is difficult to form a system-level integrated business application. The smart grid highly integrates and integrates many advanced technologies such as communication technology, computer technology, sensor measurement technology, and control technology with the original grid facilities. Compared with the traditional grid, the smart grid further expands the panoramic real-time information of the grid. The acquisition capability can achieve the acquisition, integration, analysis, reorganization and sharing of various real-time information of the system during the entire production process through a safe, reliable and common communication channel. By strengthening the analysis, diagnosis and optimization of real-time and dynamic status information of the power grid, it can provide a more comprehensive and refined display of the grid's operating status for grid operation and management personnel, and give corresponding control plans, backup plans and auxiliary decision-making strategies. Maximize the safety, reliability, economy and environmental protection of power grid operation. The state maintenance of the smart grid will not only be limited to the state maintenance of the power grid equipment, but will inevitably extend more complex advanced applications.
2 Key technologies for smart grid status detection
The application scope of smart grid condition detection will no longer be limited to the narrow scope of condition maintenance, life cycle management, etc., but will be expanded to areas such as safe operation, optimized dispatch, economic operation, high-quality service, and environmental protection operation. The smart grid status detection technology should cover the following aspects: grid system-level panoramic real-time status detection; true life cycle management of power grid equipment; optimal grid operation mode; timely and reliable grid operation warning; real-time online rapid simulation and auxiliary decision support ; Promote economic, environmental protection and efficient operation on the power generation side [4]. This paper mainly discusses the problems that need to be studied and solved and the expected goals of research directions such as transmission line equipment management, status maintenance and life cycle management, and intelligent substation related technologies.
2.1 Management of transmission line equipment
The key technology of transmission line intelligence is the intelligent technology based on informatization, digitization, automation and interactive monitoring, evaluation, diagnosis and early warning of transmission line equipment to ensure the safety of transmission line operation. The management of transmission line equipment is an important aspect of realizing the detection of transmission line status and the intelligentization of transmission lines. Specifically, the research content of transmission line equipment management needs to be covered as follows.
(1) Research on the function of "self-detection" of transmission line equipment: study the characteristic parameters and detection and monitoring technology of transmission equipment; construct equipment status monitoring and diagnosis roadmap; roll over optimization maintenance strategy; construct transmission line state maintenance system.
(2) Research on the function of "self-assessment" of transmission line equipment: build a digital evaluation system of equipment operation status to realize equipment self-assessment function; construct equipment failure risk assessment model to realize controllable management of equipment risk cost; establish equipment economic life model.
(3) Research on the function of "self-diagnosis" of transmission line equipment: study the typical failure mode of main equipment, extract effective characteristic parameters, and give fault evaluation criteria; study the characterization method of equipment status when multiple characteristic parameters reflect the same failure mode; step by step Establish a smart device technology system with self-diagnosis function.
(4) Research on the function of “accident early warning and auxiliary decision-making†of transmission line equipment: constructing equipment operation reliability prediction model, realizing the numerical prediction function of equipment failure; realizing the optimized management of equipment life cycle cost; developing the auxiliary decision-making system in combination with the characteristic parameters of equipment , So that it can provide equipment reliability numerical forecast information for power grid dispatching, and provide advanced early warning function of power supply safety.
2.2 Condition maintenance and asset life management
In the process of condition maintenance, the collection and management of equipment basic data, the evaluation of equipment status, fault diagnosis and development trend prediction, and remaining life assessment are four aspects: the utilization, maintenance, transformation, and update of assets in the process of asset life cycle management The basic work that needs to be carried out, and the management of asset planning, design, and procurement can also be inseparable from the feedback of historical data, status, and health records during the use and maintenance of the equipment. For the state maintenance and asset life management of transmission and transformation equipment for smart grids, the following content needs to be studied.
(1) Based on the self-diagnosis function of the failure mode and the numerical prediction technology of the failure risk: taking oil-immersed power transformers, circuit breakers and GIS as the objects, on the basis of the primary intelligent equipment, further develop self-detection parameters and improve self Research on the detection function; in terms of self-diagnosis, carry out research to improve the level of intelligence, realize the numerical prediction of equipment failure probability and failure risk, and serve the safe operation management of intelligent equipment and even the power grid.
(2) Auxiliary decision-making for state maintenance: based on the basic functions of auxiliary decision-making for state maintenance of power transmission and transformation equipment, research on maintenance planning and optimization technology based on state maintenance, equipment status analysis and fault diagnosis technology, and typical defects of transmission and distribution equipment Standardization technology, equipment manufacturer's unique identification establishment and tracking technology, online monitoring data access technology, etc., and improve the evaluation guidelines for expanding transmission and transformation equipment.
(3) Asset life cycle management: Based on the existing mature software packages, production management, scheduling management, marketing management, reliability management, bidding management, plan statistics and other applications, the research of power grid assets from planning, design, procurement, Various key technologies of informationization in the life cycle management of construction, operation, maintenance, technical transformation and scrapping, focusing on the research of equipment asset holographic information model, equipment asset life cycle management and control technology, power equipment supply based on asset performance and service support Comprehensive evaluation technology, equipment asset life-cycle optimization evaluation decision-making system and related algorithms, and technology-based overhaul-assisted decision-making technology based on the asset life cycle, etc., and finally realize the asset-full Life cycle management system.
(4) Smart grid-oriented equipment operation and maintenance strategy: research on smart grid-oriented substation inspection technology, inspection items and inspection technical specifications; research on smart grid-oriented power outage test and maintenance strategy; research completed in line with the characteristics of smart grid operation Equipment outage test and maintenance modeling; research on the on-site maintenance, inspection and verification technologies and strategies of intelligent accessories. Establish a set of equipment operation and maintenance technology system and standard system for smart grid to meet the requirements of smart grid operation and management.
(5) Equipment life cycle cost management strategies for smart grids: study the failure modes and failure probabilities of various types of primary equipment, study the maintenance models (required time and resource distribution rules) under various failure modes, and study various failures Risk loss under the model (overhaul cost, power supply loss cost, social impact conversion cost, etc.). Facing the smart grid, study the technical and economic life model of equipment, establish a life cycle cost model according to new and old equipment, and a corresponding equipment maintenance and replacement strategy. Facing the smart grid, complete the equipment life cycle cost management technology system and standard system to meet the requirements of smart grid operation management.
2.3 Research on related technologies of smart substations
Smart substation is the physical foundation of smart grid, and its core technology is intelligent primary equipment and networked secondary equipment. Research content related to smart substation technology should include the following aspects.
(1) Smart substation technical system and related standards and specifications: study the structure and technical system of smart substations, clarify the definition and positioning of smart substations, formulate corresponding standards and specifications, guide the construction and operation of future smart substations, and improve the standardization of smart substations Degree, openness and interoperability.
(2) Dynamic data processing of intelligent substations: by developing an open intelligent substation system and improving communication equipment to obtain a faster data collection rate, or storing online measurement data in a local intelligent substation, and then, in Relevant data is exchanged between various intelligent substations, and each intelligent substation is regarded as an agent, so as to realize the application of full digital real-time decision-making based on MulTI-Agent. On the side of the high-level dispatch center, it is necessary to develop a wide-area panoramic distributed integrated EMS / WAMS technical support system.
(3) Automatic reconfiguration technology of intelligent substation systems and equipment: establish model self-description specifications of intelligent devices, realize automatic modeling and model reconstruction of systems and equipment in intelligent substations, and realize intelligentization during system expansion, upgrade and transformation , Rapid system deployment, testing, verification and error correction, improve the security of the intelligent substation automation system, and reduce the system construction and debugging cycle.
(4) Distributed coordination / adaptive control technology for intelligent substations: R & D distributed coordination / adaptive control technologies and methods to solve the adaptive modification of relay protection, stability recovery and reactive power compensation device settings caused by flexible zoning to achieve solutions After the column, the distributed intelligent control of the microgrid including power generation and the substation.
3 Conclusion
State detection technology is a technology for state-based maintenance or predictive maintenance services. Its development stems from the technical needs of state maintenance for the acquisition, analysis, and evaluation of power grid equipment state information. In the future state inspection of smart grids, it is imperative to improve the accuracy of information collection, strengthen the reliability and accuracy verification means of collected information, and improve the availability of monitoring information through remote, on-site verification and calibration techniques. At the same time, the information processing of the smart grid state detection must be processed in layers for different application needs. The application scope of smart grid state detection will no longer be limited to state maintenance, full life cycle management, etc., and will be expanded to areas such as safe operation, optimal dispatch, economic operation, and quality service. In short, the future smart grid state detection technology will far exceed the scope of traditional power grid state detection, the detection range will be greatly expanded, all-round coverage, and will provide extended application support for grid operation, comprehensive management, etc., not just limited to the grid Equipment monitoring.
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