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Power system protection devices computer anti-interference measures

Equipment failure, lock protection device to prevent the protection device malfunction, and promptly notify the operating duty; (3) The fault-tolerant design approach, the use of redundant protection devices do not ask off to online operation. 3.2 The main factors to be considered interference (1) a reasonable selection of high quality computer chips and other semiconductor devices, designed the circuit layout and manufacturing process, cutting off all power ≤ a share of a foot Dion ● Electric Safety Technology Volume 5 ( 7,[link widoczny dla zalogowanych], 2003) magnetic coupling means to minimize the impact of disturbance on the protection devices,[link widoczny dla zalogowanych], (2) the appearance of signals due to interference with a large random, once the interfering signals occur within the protective device, should be considered with to the problem and take countermeasures. 3.3 Optical coupling of the interference typical circuit for the operation of power plants and substations in power system computer protection device,[link widoczny dla zalogowanych], the power supply circuit, analog input circuit, the switch input and output circuits and communications ports are introduced through a cable to the more distant analog components, these circuits are coupled to the microprocessor-based protection to interfere with the primary media device, the circuit should be isolated by optical coupling devices. (1) power system protection equipment computer data acquisition system usually has two forms: using successive approximation A / D converter data acquisition system and the use of voltage / frequency transform analog / digital converter data acquisition system. They block diagram shown in Figure l and Figure 2. Figure 1, successive approximation A / D conversion of the data acquisition system in Figure l computer protection device can converter internal and external mutual inductance circuit is completely isolated, there is no direct electrical signal contact, helping improve noise immunity. Figure 2 voltage / frequency transform analog / digital conversion of the data acquisition system in Figure 2, AC converter to ensure internal and external device there is no direct electrical contact. Surge absorber device not only can improve the anti-interference ability, and can play on-chip over-voltage protection. (2) Anti-interference digital inputs typical circuit shown in Figure 3. + EC-EC Figure 3 digital input circuit of the interference typical circuit when the external contact is closed, a current flows through the optoelectronic devices - light-emitting diodes, the phototransistor turns on, and when the external contact is open,[link widoczny dla zalogowanych], no current flow through the light-emitting diode, phototransistor closed. It can cut off the external interference signals fleeing into the internal microprocessor protection device. (3) digital outputs of the interference typical circuit shown in Figure 4. Coding scheme used in the circuit so that each road driving circuit switch output by two parallel port output lines to control, through the inverter and NAND gate implementation, the use of non-door to meet two conditions can the actuator action to improve the circuit's noise immunity. ◆ Figure 4 for a digital output of a circuit in a typical circuit interference of other anti-jamming measures 3.4. (1) power supply filtering. Additional entry in the power supply filter. (2) analog input circuits of electrostatic shielding. (3) The magnetic shielding and twisted pair. Different voltage levels of lead and switch output voltage level of the power cord of different separate input and output terminals after wiring and the alignment of the strength of separation. (4) improve the sensitivity circuit noise immunity. (5) rational design of ground discharge circuit. Anti-jamming measures 3.5 Problems in the work of computer protection program, should be set for error detection and bad data identification routine functions to ensure the accuracy of the results of software operations. (1) sampling the input analog data to the anti-jamming measures. In digital protection, enter a three-phase analog voltage, zero sequence voltage, phase current and zero sequence current can be sampled by the laws of their own error checking of data. (2) operation in the process of verification measures. The whole computing process two or more checking, the process used to test whether the expression is wrong. (3) Export atresia. Exports in the protection of the hardware trip circuit, designed to receive multiple trips in a row command,[link widoczny dla zalogowanych], the trip circuit to perform the export is not allowed to receive instruction on the trip. (4) Measures to prevent the program off the track. Using a dedicated hardware circuit to detect the process derailed, and automatically resume normal operation. Such as the use of microcomputers in the timer / counter chip and use of the microprocessor timing circuit to achieve the re-start. 4 Conclusion with high reliability, strong anti-interference ability level and the third generation of network communication computer protection device has been widely used in power system applications, computer protection device itself is also in line with national standards for anti-jamming capability, but in the actual operation , you should also note the following two points: (1) computer protection device is disabled, you should first leave the protection of the export of plate, and then stop DC power supply. (2) Computer AC power protection devices, digital input, output circuit operation, complete protection device should be discontinued. (Received IEI on :2002-12-26) Ang Li mushroom lamp Spanish fly.
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