Functional design principles of the hottest substa

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Abstract: substation automation is the trend and requirement of power system development. This paper introduces the general structural types of substation integrated automation, and discusses in detail the functional requirements of the automation system and the design principles of secondary equipment

key words: functional requirements for substation automation design 1 Introduction with the rapid development of the power industry, the scale of the power system continues to expand, the operation mode of the system is more and more complex, and the requirements for the automation level are higher and higher, thus promoting the continuous development of power system automation technology. Microcomputer protection, fault recorder, computer monitoring system and computer dispatching automation have been successfully applied to the power system. In line with the degree of automation, the requirements for power system relay protection devices are also increased. At present, the traditional electrical relay protection testing device has been difficult to comprehensively test all aspects of the characteristics of relay protection devices, and it is no longer suitable for the needs of technological development. In order to avoid repeated investment and improve the level of information resource sharing, it is necessary to standardize the information collection, processing and transmission of substation automation system, and comprehensively consider the functional configuration in the station. At present, the substation automation system generally adopts the station computer network based on SCADA. Through the comprehensive design, the time of repeated configuration of secondary equipment is reduced, the secondary circuit is reduced, and the load of current transformer and voltage transformer is reduced, so as to simplify the secondary circuit design, ensure the consistency of data, and achieve the sharing of software and hardware resources on the basis of reliability as much as possible, The operation and management level of the substation is improved, and the purpose of reducing personnel and increasing efficiency and improving the safe operation level of the substation is achieved. 2. Functions of substation integrated automation 2.1 relay protection functions the substation integrated automation system should have all the functions of conventional substation system protection and component protection equipment, and should be independent of the monitoring system, that is, when the software and hardware of the system send out on the machine for end face sliding friction experiment and exit the operation due to failure, the relay protection unit still operates normally. In addition to the relay protection function, microcomputer protection also needs to have other functions. (1) display function of analog quantity. The system shall be able to display analog parameters such as current, voltage, active power, reactive power and electric degree, which can still meet the operation monitoring when the communication is out of operation. (2) fault recording function. The system shall be able to display fault time, current, voltage, switch displacement, protection action status, etc. (3) it can store multiple sets of fixed values, and can locally modify and display fixed values. (4) communicate with the monitoring system, be able to receive the command of the monitoring system, select and modify the setting value, send fault information, protection action, current setting value and self diagnostic signal, etc. In addition to local, it also needs to be able to realize remote query and set protection settings. This function also has remote/local locking, operation authority locking and other measures. (5) all plug-ins in the system have self diagnosis function. 2.2 information collection function for the substation of the distributed automation system, the information is collected by the bay level i/o unit. For substations with conventional four remote functions, information is collected by RTU. A separate electric energy acquisition device should be used for the acquisition of electric energy. The system collects the necessary information in the safe operation, mainly including the following aspects. 2.2.1 remote measurement (1) main transformer: active power, reactive power, current on each side, oil temperature on the upper layer of the main transformer and other analog quantities. AC sampling is adopted for analog quantities to improve accuracy. The main transformer has lechal, which can use the navigation on the to point out the user's forward load tap changer position (when it is processed by telemetry). (2) line: active power, reactive power, current. (3) phase current of bus section breaker. (4) bus: bus voltage, zero sequence voltage. (5) capacitor: reactive power and current. (6) zero sequence current of arc suppression coil. (7) DC system: floating charge voltage, battery terminal voltage, control bus voltage, charging current. (8) transformer used: voltage. (9) system frequency, power factor, ambient temperature, etc. 2.2.2 remote signaling quantity (1) breaker knife switch position signal. (2) remote/local switching signal of circuit breaker. (3) abnormal locking signal of circuit breaker. (4) protection action, warning signal and fault signal of protection device. (5) on load tap changer position of main transformer (when handled by remote signaling), abnormal oil level signal, cooling system action signal. (6) automatic device (function) switching, action and fault signals, such as voltage and reactive power integrated control, low cycle load shedding, standby power supply device, etc. (7) DC system fault signal. (8) used transformer fault signal. (9) other main station accident signals and pre notice signals; General signal of bus grounding of each section; Small current grounding signal of each outgoing line; Reclosing action signal; Failure signal of downstream channel of telecontrol terminal; Action signals of fire-fighting and safety protection devices, etc. According to the characteristics of the equipment and the need to ensure safe operation, corresponding special signals can be added or some remote signaling quantities can be combined. 2.2.3 remote control quantity (1) opening and closing of circuit breaker. (2) on load tap changer position adjustment of main transformer. (3) the neutral grounding knife switch of the main transformer is opened and closed. (4) remote reset of protection and safety automatic device signals. (5) if conditions permit, the standby power supply at the high-voltage side of the substation can be switched on and off remotely. (6) remote switching on and off of conditional substation voltage and reactive power integrated control. (7) remote switching on and off of DC charging devices in conditional substations. 2.2.4 electric energy (1) active electric energy, reactive electric energy and time-sharing electric energy on each side of the main transformer. (2) active electric energy and reactive electric energy of each feeder. (3) the models of active electric energy, reactive electric energy and time-sharing 2 testing machine of the user's private line shall meet the specified energy and maximum demand of relevant standards. (4) used active electric energy of transformer. 2.3 equipment control and locking functions (1) control the opening and closing of circuit breakers and knife switches. (2) switching capacitor banks and regulating transformer taps. (3) inspection of protection equipment and setting of setting value. (4) withdrawal and input of auxiliary equipment (such as air conditioning, lighting

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