Improvement of control method for feeder circuit breaker and isolation switch of traction substation
Steam boiler water supply frequency conversion speed control system Xiangyu line Yuhuai section traction substation feeder adopts ZN-27.5/1250 vacuum circuit breaker, equipped with CT12 spring operating mechanism, and the corresponding feeder isolation switch is GW4-27.5 type. With XC-operating condition, the joint action of the circuit breaker and the isolating switch, that is, the circuit breaker can only perform the screen-controlled opening and closing operation when the isolating switch is in the joint position, and does not consider various operation modes of the abnormal situation T. Inconvenience to the on-site operation and maintenance.
1. The problem is raised by taking the closing as an example. Under the normal operating conditions, the action process of the circuit breaker and the isolation switch is: in the control panel h, the control switch is placed in the control position, and then the control switch is switched on first. The closing circuit of the switch closes the isolating switch. After the isolating switch is closed, the closing control circuit of the circuit breaker is closed by the contact of the position relay GH, and then the circuit breaker can be completed.
When the feeder fails to have a ground fault, it is necessary to determine whether the fault location is within the substation feeder disconnect switch or outside the substation feeder disconnect switch. The feeder disconnector must be disconnected before the breaker is closed. However, the purpose of this operation cannot be achieved on the control panel, that is, the purpose of finding the fault point in the segment cannot be achieved. In actual operation: the control mode switch must be placed in the local position, then go to the outside, perform local operation in the isolation mechanism box, separate the isolation, and then go to the handcart room in the high pressure room to operate the breaker panel. Close the button, close the circuit breaker and test the inside part.
The problem is that the circuit breaker is installed in the handcart: the closing button is installed on the circuit breaker. If the insulation of the circuit breaker is broken, the strong arc will pose a threat to the operator's personal safety. My unit has repeatedly occurred due to vacuum bubble bursting, circuit breaker insulation breakdown, arc will be crushed by the baffle baffle and open circuit, Zhong Yan opened Yang Dequn personnel to Zhuang control room, outdoor feeder side, high pressure room back and forth Operation, long switching time, prolonging the power outage time of the r accident, and easy to make mistakes in the busy, resulting in a larger accident.
2. Solution We have made improvements to the drawbacks that the circuit breaker and the isolating switch can only be linked and cannot be step by step. The specific improvement measure is to add a conversion sweat switch on the feeder control screen. Its working principle is: in normal operation, this conversion is closed to the neutral position, and the linkage control mode and the action process are no different from those introduced before. When step-by-step operation is required, the switch is placed in the left position, and the traditional steam boiler hydration method of the Inner Mongolia Baotou Iron and Steel Institute, which cuts off the isolating switch, is measured by the electrode sensor to measure the high and low water levels. When the boiler water level is lower than the low water level, the feed water pump is started to replenish the boiler; when the water level is reached, the pump is stopped. Because the high and low water levels generally differ by about 20cm, the water level reaches the high water level soon after the pumping, so the pump starts and stops frequently, resulting in large mechanical loss, high energy consumption and high failure rate.
In view of the above problems, this paper proposes a constant water level variable speed automatic hydration system, which not only improves the safety of the system, but also saves energy. Through practical application, it has achieved good economic benefits.
The frequency conversion speed control system is constructed as shown. The entire system is a closed loop negative feedback control system. The water level sensor adopts WS (1150DP type differential pressure transmitter, which is operated by the power supply, and short-circuits the r-position of the normally open contact of the relay GH. At this time, the division and operation of the circuit breaker is not isolated. Control, reached the N of the separate split circuit breaker.
According to this method, we improve the R: a traction substation in the Huaihuan section. Each substation only adds one conversion hose and a control cable that controls the W and protects the indirect-裉4m length. Feeder circuit breaker linkage and - control mode conversion, on-site construction, the number of feeder circuit breakers and disconnectors according to the number! 4: Select the model of the conversion Khan off, (Editing Water Jia) Jia Hua Li Jie Wang Chen differential capacitor is a capacitive transmitter composed of detection principle. The lower limit pressure value detects the steaming n pressure, 丨: pressure limit. Liyi detects the pressure of the water Hi steam, and the upper and lower pressure differences are the water level pressure values. Therefore, the f-limit detection point must be installed on the steam portion of the water, and the upper limit detection point is installed below the water surface. Through the internal string 25n resistor, the 420mA DC current output signal is converted into 丨5V DC voltage signal, compared with the given value G, into the PID operation, PID output 010V DC signal, control the inverter frequency water level higher than the given value, PID The output voltage is reduced, the inverter frequency F is lowered, the pump is decelerating, and the water level is decreasing. When the water level is low, the PID output voltage increases, the inverter frequency rises, the pump increases speed, and the water level rises, so that the water level is always constant. value. Its control principle block diagram is as follows.
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