Abstract: With the development of the national economy and the accelerated growth of power load, the original power grid has become an urgent problem due to long-term investment shortage, outdated equipment, and backward technology.
Keywords: Distribution Network Power Supply Reliability
I. Importance of distribution network power supply reliability
Distribution network is an important part of the power system. Its security and reliability will directly affect the development of the national economy and the living standard of the people. According to incomplete statistics, 80% of the power outages in China are caused by distribution network faults. Therefore, it is of great practical significance to improve the reliability of power supply in the distribution network.
The power supply reliability of distribution system users is a major indicator of the power supply system's ability to continuously supply power to users. During the statistical period, ratio of the total number of hours of the 10 kV Distribution Network's effective power supply time to the number of hours during the statistical period: Power Supply success rate = [1-Σ (each household's power outage time)/(total number of users × hours of one year)] × 100%. The distribution system is directly connected to users, which is an important part of power system power supply and distribution. The medium-voltage distribution network covers every street and is then extended to every electricity customer through the low-voltage distribution network. Once the power distribution system or equipment fails or is overhauled or tested, the power supply of the system to the user will be interrupted, it will cause different degrees of losses to workers, agricultural production, and people's lives. For a long time, the development of the distribution network lags behind and cannot meet the needs of customers. Therefore, the construction and transformation of the distribution network must be strengthened to improve the reliability of power supply to meet the development requirements of the power industry.
2. Measures to improve the reliability of Distribution Network Power Supply
(1) Starting with technology, improving power supply reliability
1. Strengthen technical measures and vigorously promote the use of new products
(1) high-voltage cables and insulated wires are gradually used in the transformation of rural power grids. In the transformation of rural network, cables of different specifications are used for about 2.96 km, and insulation cables are used for areas with insufficient security distance. The specification ranges from 35 ~ 120mm, low voltage insulation cable, specifications from 35 ~ , Greatly reducing the failure rate and improving grid reliability and security.
(2) pin insulators are replaced with Rod Insulators. pin insulators often break down during thunderstorms due to poor withstand voltage, resulting in single-phase grounding and difficult to find fault points, which prolongs the power outage time, after Rod Insulator is used, the situation is greatly improved.
(3) Replace the Oil Circuit Breaker with a vacuum circuit breaker. The technical performance and safety of vacuum circuit breaker are much higher than that of oil circuit breaker.
(4) Metal Oxide lightning arresters replace valve lightning arresters to enhance line lightning protection and prevent overvoltage.
(5) A fully-Sealed Transformer, the original S7 transformer, is put into operation, causing the transformer to breathe too much water, affecting transformer life and operation safety. Nowadays, fully-sealed transformers are gradually used, which are safe, reliable, and economical. Transformer accidents are reduced after application.
2. advanced equipment is used to automate the distribution network. Advanced Equipment (low failure rate) is used to monitor the distribution network in real time through the communication network, and the operating conditions of each component in the network can be grasped at any time. faults can be eliminated without occurrence. To automate the distribution network, you can automatically isolate fault segments and restore power to non-fault segments. by choosing a reasonable and locally appropriate integrated automation system solution, while implementing a set of monitoring measures, strengthen the collection of real-time Power Grid status, equipment, switch operation times, load management conditions, and trend trends, implement network management, develop optimization schemes, and improve the reliability of the distribution network power supply, 99.99% of the power supply success rate can be achieved. In addition, the contact switch and switch can work together to transfer part of the power loss caused by the fault to other systems to restore power supply, thus shortening the power outage time of non-Faulty lines.
3. Pay attention to the quality of construction and maintenance. The quality of construction and maintenance is an important part to improve the reliability of the distribution network. Strict control is required to reduce the failure rate. In particular, the design of non-standard fittings for distribution networks and the quality of galvanized materials are imperative. Otherwise, a large number of serious corrosion fittings will be replaced, resulting in heavy workload and unguaranteed power supply reliability. This is easy to neglect and must be highly valued. Use highly reliable power generation and supply equipment to maintain and run power generation and supply equipment.
4. Improve the reliability of power supply lines and adopt dual-return lines for important lines in the system. At present, there are few dual-return lines in the rural electricity distribution network. The dual-return lines provide power, provide high transmission capacity, and ensure high reliability of transmission lines. Line switches are added to the main trunk line to set up branches and limit the failure range of branch lines to reduce the power outage range.
(2) strengthen management and improve power supply reliability
1. Establish a three-level assurance system at the decision management layer, indicator control layer, and support layer. Power supply enterprises should set up a leading group for reliability, with the participation of key leaders and dedicated personnel from the Office, enterprise management, biotechnology, marketing, finance, scheduling and relevant departments, it is mainly responsible for formulating and implementing various management, technical measures, and discussion and formulation of the power supply reliability improvement plan for power distribution network construction, earnestly implementing relevant regulations and measures of superiors, and earnestly fulfilling Reliability Indicators. Relevant departments are also equipped with relevant reliability part-time personnel to conscientiously implement the higher-level rules and regulations on the reliability of power supply, and supervise and urge the completion of the Reliability Assessment Indicators issued by the company. The reliability management part-time personnel of relevant departments form a power supply reliability management network, which is responsible for the specific management of reliability, so that information transmission and related data can be organized and reported, and grid planning, design, infrastructure construction, construction, production and operation work in an orderly manner.
2. Reform the power outage Repair System and plan to manage power outages. Strengthen power stop management. Implement the weekly production meeting system. Leaders in charge of production will arrange the power outage and repair work in a unified manner, strengthen the communication of power outages between departments, implement one power outage, cooperate with multiple teams, avoid repeated power outages, and prohibit unplanned power outages, eliminate random power outages. Formulate monthly and weekly plans for reporting in a timely manner. The scheduling department should manage and coordinate the plan in a unified manner, and prepare a reasonable power outage repair plan to combine power outages such as substation, line, industry expansion, and rural network transformation.
3. Automated distribution network and computer management.
(1) Scheduling Automation: automation of the distribution network is an inevitable trend to improve the reliability of the power supply. Under the current conditions, the switch station and substation must be automatically scheduled. The remote motion of the switch station is: Remote, remote, switch and power-off status, semaphores of various signal relays, 10 kV bus voltage, and 10 kV incoming and outgoing line current. Terminal RTU adopts RTS-200 type AC sampling distributed modular structure, scheduling end is SWJ-700 type system, wireless channel, with a wireless phone.
(2) MIS development: MIS development ensures the reliability of power supply from management. The key in MIS is the development of GIS (Geographic Information System), which requires a good map. The location of each pole is marked on the map, and all power supplies, substations, and scheduling rooms of the company are connected with optical cables for information sharing. This makes the distribution network play a major role in planning, locating fault points, displaying the power outage range, and finding weak links in the distribution network.
We will continue to focus closely on the decision-making and deployment of "maintaining growth, protecting people's livelihood, and maintaining stability", and undertake the enterprise spirit of "Striving to surpass and pursue excellence" to improve the reliability of distribution network power supply, establish a good power supply enterprise image to ensure continuous supply of qualified power to users, so as to achieve comprehensive quality management and security management, and increasingly meet the requirements of safe operation of power grids and high-quality services.