Automatic switching scheme of the hottest standby

Automatic switching scheme of standby power supply

Abstract: automatic switching device of power supply is widely used in power system, such as automatic switching of voltage transformer power supply, automatic switching of standby power supply, etc. This paper puts forward several schemes for automatic switching of voltage transformer power supply and station power supply, analyzes and compares them, and puts forward some suggestions that new controllers can be tested automatically from the perspective of safety, reliability and maintainability

key words: automatic switching device standby power supply voltage transformer power station power supply power system standby power automatic switching device is an important measure to improve the safe and reliable operation of electricity. Voltage transformer can provide power supply for control, protection, measurement, signal and other circuits; The station power can provide control, measurement, lighting, maintenance and power in the substation, as well as DC system power supply and battery charging power supply through rectifier devices. It can be seen that it is particularly important to maintain the uninterrupted voltage transformer and station power supply. Now several automatic switching schemes of voltage transformer power supply and station power supply are analyzed and compared from the perspective of operation. 1. Automatic switching of voltage transformer power supply there are roughly the following schemes for automatic switching of voltage transformer power supply. 1.1 electromagnetic automatic switching device 1.1.1 one way automatic switching of two power supplies with priority is shown in Figure 1. When 1yh is powered on, 1zj coil is powered on, two pairs of 1zj normally open contacts at 101 and 103 are closed, two pairs of normally closed contacts at 105 and 107 are open, and power such as control signals are provided by 1yh. When 1yh loses power, 1zj coil loses power, two pairs of 1zj normally open contacts at 101 and 103 are opened, and two pairs of normally closed contacts at 105 and 107 are closed. When 2yh is powered, power supply such as control signal is provided by 2yh. At this time, if 1yh returns to power, 1zj coil is powered on. The same principle as above, and the power supply such as control signal is still provided by 1yh. This scheme is characterized by one-way automatic switching of two power supplies, which can be divided into power priority levels. 1.1.2 two way automatic switching of two power supplies without priority is shown in Figure 2. When 1yh is powered on, 1zj coil is powered on, two pairs of 1zj normally open contacts at A1 and A2 are closed, 1zj normally closed contacts in 2ZJ coil circuit are opened, and the power supply of control and signal circuits is provided by 1yh. When 1yh loses power, 1zj coil loses power, two pairs of 1zj normally open contacts at A1 and A2 are opened, and 1zj in 2ZJ coil circuit. The origin of this project is that the normally closed contacts of a very insignificant recycling plastic machine are closed. At this time, if 2yh has power, 2ZJ coil is powered on, two pairs of 2ZJ normally open contacts at A3 and A4 are closed, 2ZJ normally closed contacts in 1zj coil circuit are opened, and the power supply of control and signal circuit is provided by 2yh. In the same principle, when 2yh loses power, if 1yh has power at this time, the control and signal power supply will be provided by 1yh through the automatic switching device. This scheme is characterized by two-way automatic switching of the two power supplies, which are standby for each other, and there is no priority. 1.2 microcomputer automatic switching device the above two automatic switching schemes of voltage transformer power supply are electromagnetic. At present, the microcomputer type automatic switching device is being popularized and used in some conditional areas. Microcomputer based automatic switching device, such as ref543, contains functions such as protection, control, measurement, monitoring and communication, and its functions are extended by using special function library. In order to improve the reliability of microcomputer protection, the ref543 feeder terminal device is also equipped with a powerful self-test system. At the same time, the self-test output relay of the device gives a fault signal and locks the protection trip output. Microcomputer based automatic switching device, such as ref543, when realizing the automatic switching of standby power supply, in addition to detecting voltage, it also adds current locking protection, which further enhances the reliability of automatic switching action, but the work of microcomputer based protection device is vulnerable to electromagnetic interference. The microcomputer type automatic switching device has safe action and flexible function expansion. It is more suitable for occasions with high protection performance requirements, more protection differential coordination, and complex protection principle composition. It also has a small amount of maintenance, but the price is relatively expensive, and it needs to be equipped with special detection instruments and calibration tools. Electromagnetic automatic switching device has mature technology and proven reliability record, is not affected by electromagnetic interference, and has a wide range of risks. 1. Price fluctuation of main raw materials; 2. The risk of declining prosperity of the industry; 3. Industry competition aggravates risks. Users can choose according to their own conditions in the selection process, which has a long service life. 2 automatic switching of station power supply 2.1 the electromagnetic automatic switching device is shown in Figure 3. Station power supply 1 (A1, B1, C1) and station power supply 2 (A2, B2, C2) are powered on. When qm1 and qm2 switches are turned on, CJ1 coil is powered on, CJ1 normally closed contact is opened, station power (a, B, c) is provided by station power supply 1, and CJ1 normally open contact is closed, XD1 indicator light is on, indicating that station power supply 1 is in working state. When station power supply 1 (A1, B1, C1) loses power, CJ1 coil loses power, CJ1 normally closed contact is closed, cj2 coil is powered on, and station power (a, B, c) is provided by station power supply 2. At this time, CJ1 normally open contact is opened, cj2 normally open contact is closed, xd2 indicator light is on, indicating that station power supply 2 is in working state. In the same principle, when the station power supply 2 loses power, the station power is supplied by the station power supply 1 through the automatic switching device. This automatic switching scheme of station power supply is characterized by two-way automatic switching of two power supplies, which are standby for each other. 2.2 ATS (microcomputer based automatic switching) device the core of ATS device is generally digital microprocessor controller and logic circuit board, which includes the functions of detecting voltage, frequency, time-delay setting, monitoring and system diagnosis. It meets the requirements of emergency and standby power system application, and can switch and standby the two power supplies to each other. It has the functions of automatically judging the closed switching and open switching. When the open switching, it can attach a phase angle detector to compare the phase angle difference between the two power supplies, provide the function of in phase conversion, and allow the two power supplies to perform the closed conversion function under the condition of a certain frequency difference, phase angle difference and voltage difference. If the withdrawable ATS device is used in the design, it can greatly facilitate maintenance and testing. At the same time, through the setting of microprocessor, it can meet the needs of distribution automation. Taking asco940 ATS device as an example, its application in practice is shown in Figure 4