Guide to Selecting Preferred Distribution Network Automation Equipment

Author: Chief Editor: Xu Layuan
Publisher:
Publish Date: 1998-06-01
Features: Summary This book systematically analyzes the types, characteristics, and applicability of automation based on the development of distribution networks in China, proposing the necessity of adopting new technologies and equipment to improve and promote the automation of distribution networks. It describes the basic structure of new high-voltage switchgear, provides a detailed analysis of the performance, structure, and application of devices such as vacuum and sulfur hexafluoride circuit breakers, reclosers, and sectionizers, and proposes guiding principles for the development of China's distribution networks. It compares and explains the main equipment, functions, application effects, and performance of distribution networks, elaborates on the basic principles of switchgear, and systematically introduces distribution network automation solutions and the necessary secondary protection and control equipment, outlining fundamental ideas and plans suitable for the automation development of China's distribution networks. The book is divided into chapters: Chapter 1 covers the development and current status of distribution networks, Chapters 2 and 3 introduce high-voltage distribution switchgear and its technical requirements, Chapter 4 discusses load switches, and Chapters 5 to 10 respectively introduce vacuum, sulfur hexafluoride-type reclosers, sectionizers, fuses, and other equipment. Chapter 11 covers relay protection devices and monitoring devices. The appendix includes the "Design Code for Rural Small-Scale Substations" and distributed multi-functional power monitoring instruments for reference. This book serves as a reference for electrical design, manufacturing, operation, and maintenance personnel in power systems engaged in distribution network automation engineering, high-voltage electrical equipment, and power system application fields. Excerpt: Chapter 1 Development and Current Status of Distribution Networks Distribution networks directly transform high-voltage power sources (6–35kV/level) into electricity for industrial, agricultural, urban residential, and commercial use. They cover a wide area and directly affect people's lives and activities. For a long time, due to issues such as overemphasizing generation and neglecting supply and operation, China's distribution network infrastructure has been relatively weak, equipment is simple, and power supply reliability is poor. With economic development, rising living standards, and the needs of modernization, distribution networks have become the most important and direct part of the power grid, a matter of great significance to the national economy and people's livelihood. The development of China's distribution networks has naturally formed two concepts: rural distribution networks and urban distribution networks. Urban distribution networks, with economic growth, have developed rapidly, and the technical performance of various equipment has improved significantly. Power supply is now widespread, and reliability requirements are gradually increasing, striving to prioritize high-reliability, pollution-free, non-hazardous power supply systems, with equipment investment placed in a secondary position. In contrast, China's vast rural areas (rural distribution networks) face further development, but due to insufficient funding, equipment performance, and poor personnel technical skills, the development of rural networks is hindered. Overall, rural and urban distribution networks in China share certain commonalities but also have fundamental differences, so the requirements for rural distribution network automation and urban distribution network automation are different. Due to differences in geographical conditions and power grid development across countries, the solutions and implementation requirements for rural and urban distribution networks also vary. Therefore, for a country to achieve distribution network automation, it should be based on its national conditions and circumstances, with long-term planning and phased implementation, prioritizing practicality, reliability, and automation to meet the requirements of distribution network automation. Section 1 Overview of Foreign Distribution Network Development Foreign distribution networks began developing earlier, utilizing the functions of high-voltage switchgear to achieve fault control in distribution networks (lines) as early as the 1950s. The main equipment includes reclosers, sectionizers, and ring main unit cabinets. With the development of electronics and communication technology, integrated systems combining detection, measurement, fault detection and location, automatic control, planning, and data statistics management have emerged, leading to distribution network automation solutions. Due to differences in power grid development and geographical conditions across countries, as well as varying reliability requirements, distribution network automation solutions also differ slightly, but generally can be summarized as: improved technical performance of primary equipment, long maintenance-free cycles, high reliability, and no pollution, explosion, or fire hazards; the use of advanced electronic technology to automate control of distribution equipment, achieving electromechanical integration; combining primary equipment with secondary control equipment to improve the reliability of power supply in distribution networks; quickly locating fault points to restore power supply in the fastest and simplest way; using intelligent devices to judge and isolate fault lines, with reclosers restoring power supply; strengthening database management and load management of distribution equipment, and controlling and allocating load flows at the dispatching center. It is evident that distribution network automation is not simply a matter of adopting certain equipment, but a deeper-level issue requiring a solid foundation in all aspects. When implementing automation requirements, planning should be the basis, and automation goals should be achieved gradually based on actual conditions. Section 2 Japan's Distribution Network Automation Solution Japan's distribution network development differs from that of Western European countries, with smaller power supply radii, higher reliability requirements, and more ring supply configurations. Substations use reclosing circuit breakers (circuit breakers with 2–3 reclosures) and are equipped with short-circuit fault indicators, which estimate fault distances based on short-circuit current magnitudes. 1. Three Stages of Japan's Distribution Network Japan's distribution network voltage is 6kV, with outgoing lines using reclosing circuit breakers paired with automatic distribution switches, which can close short-circuit currents and interrupt load currents. Automatic distribution switches consist of a switch body, a controller, and a power transformer. Adding fault detection devices, remote control terminals, and a central control center forms a distribution network automation system. Automatic distribution switches can achieve remote control as required. Japan's distribution network automation has gradually formed a complete system in stages, roughly divided into three phases. Stage: Automatic reclosing circuit breakers and automatic distribution switches are used to eliminate transient faults and isolate permanent faults. The second stage, building on the first, adds remote control devices to achieve remote control functions. Operation commands are issued from substations or dispatching centers. The third stage, based on the second, utilizes modern communication and computer technology to achieve centralized remote monitoring, remote control, and automated processing and monitoring of relevant information in the distribution network system. Diagrams of the principles for each stage are shown in Figure 1-1.