Fault management system of the hottest distributio

Distribution fault management system

Abstract: in the distribution system, the main function of fault management is to reduce the outage time. While analyzing the general situation of distribution development, this paper introduces the constituent subsystems of fault management, describes the technology used in each part, and puts forward a proposal for the design of automatic fault management system

key words: distribution fault management, location and isolation 1 Introduction short circuit, grounding and other faults usually contain a lot of fault information, which can be used to carry out fault location, fault isolation and restore power supply and other analysis work. From improving power supply reliability and quality, the main function of fault management in power distribution is to reduce power outage time. 2 fault location (1) fault indicator. There are many kinds of fault indicators, which are limited to space. This paper takes the short-circuit fault indicator as an example. When a short-circuit fault occurs in the distribution, if the fault cannot be isolated immediately, a huge short-circuit current will be generated, which will cause great damage to the power equipment. Therefore, a protective device for detecting and separating faults is installed on the power. For power distribution, this kind of equipment is usually installed on the end of the feeder line. If a fault occurs on a feeder line, the feeder line will be separated from the network. In order to better carry out equipment and network protection, the sampling position, shape and size of the sample used for routine inspection in production have clear provisions on its main raw materials, and the key technology is the accurate fault location technology. The short-circuit indicator is mainly used for the medium voltage of radiation or open-loop operation to find the fault location. It can be installed on the current carrying conductor that needs to be monitored, such as bus, cable or overhead line. When the current flows through the conductor, the magnetic field will trigger the short-circuit indicator. When the current exceeds the rated limit of the indicator, an optical or electronic signal will be generated, and the direction of short-circuit current from the feeder head to the fault location can be indicated by the triggered short-circuit indicator. At present, the main problem of fault indicators in the market is the lack of pointing function, which is very important for compensating the grounding fault of the network. Pointing function is also required when two-phase or three-phase faults occur in the network of decentralized power generation. The bottleneck of developing fault indicators is the measurement of voltage. The cost of the technology used should be lower than that of the inductive voltage transformer currently used, especially in high-voltage and medium voltage substations. The solution is a voltage divider based on the principle of resistance, capacitance or inductance. (2) Fault distance calculation technology. Especially in rural and suburban areas, the line distance is long. A very good supplement to fault indication is fault distance calculation. In the case of short-circuit fault, the distance can be estimated by distance relay. Another solution is to use fault current measurement to estimate the distance by comparing the measured fault current with the results of network calculation. ① Fault distance calculation using distance relay. The basis of this method is a medium voltage analysis model. Each feeder is divided into several sections, which are physically determined by medium voltage stations and branch points. The length of the section is between 50 and 500m. An alternating stress makes both sides of the crack open and close sometimes. The standard power system analysis software uses this network model to automatically calculate the off-line short circuit of each section. Short circuit calculation shall be corrected once a year. The calculation result is the static reactance of each feeder, including the fault reactance of the starting point and terminal point of each section and the complete name of the corresponding station or branch point. In case of fault, telemetry fault reactance is automatically transmitted from SCADA system to P, which also includes management, system, corporate culture and other broader and deeper connotation. C or the selection program on SCADA computer to select the corresponding segment. There is no analysis and calculation of fault location, only the selection of fault segment. The possible fault segments are displayed in a small table (1 ~ 5 segments) on the screen and submitted to the operator. ② Short circuit fault location of fault current measurement. The modern short-circuit fault location system is based on the integration of distribution data management system (DMS), substation remote control system (SCADA) and relay protection. The main idea is to compare the measured and calculated fault current. The calculation is formula, and assuming that the network topology remains unchanged when the fault occurs, the estimated distance from the fault point to the substation is obtained, and then this distance is compared with the network diagram, and the possible fault location is displayed in the distribution network diagram of DMS system in a graphical manner. 3. Fault isolation and power supply recovery (1) determine the switch position. The goal of fault location is to separate the fault or suspicious line from the line without fault and ensure the continuous power supply of other lines. The common practice is to gradually reduce the number of normal equipment connected to the fault or possible fault line. However, the premise of this algorithm is to assume that all the switchgear in the area where the power supply has not been restored is disconnected, and at least one end of these switches is connected to the area where there is no fault. The calculation process is divided into two steps: first, the network topology is analyzed only according to the switch state that can be remotely controlled; Then, the network topology analysis is carried out according to the status of all switches (which can be controlled remotely and manually). According to the network topology analysis results obtained twice and all the switch states assumed above, the fault or the area where the fault may occur can be isolated from the fault free area. In this way, changing the selected switch state can be used as a fault isolation scheme. (2) Power supply restoration algorithm. According to the results of fault isolation analysis, the boundary switch constitutes the shortest power supply path between the equipment and the switch in the area where power supply needs to be restored. It is also necessary to define that at least one circuit breaker is included in the power supply path, which is very useful, because only the circuit breaker can operate when there is load, and the disconnector can only operate when there is no load. All switches belonging to the selected power supply line and those that remain open in the simulation analysis are regarded as the scheme of restoring power supply. These switches are stored in this way, first according to the topological logic sequence of disconnectors, and then according to the topological logic sequence of circuit breakers. 4. The electric fault management system adopts the electric fault management information system, which can greatly improve the automation level of the current electric fault management. It uses the existing communication lines to power the trunk to the relevant equipment