There are many types of power users involved in the power system, among which the industrial load has a high proportion in the total power load. Due to the large load in the factory, it is necessary to select the appropriate power supply mode to ensure the safety of the power supply system. Some factory users have higher requirements for power supply reliability or are very sensitive to power quality.

There may be some problems in the operation of the power supply system of the factory, which mainly include: equipment shutdown without reason, resulting in production loss, such as sudden shutdown of frequency converter, equipment damage after lightning strike, circuit breaker trip; abnormal operation of equipment, no reason can be found, such as motor and cable heating, capacitor failure or even explosion, abnormal noise of transformer, etc.; equipment energy consumption increases, resulting in production loss It is difficult to determine the responsibility for fault in production process, such as misoperation of relay protection device, restart of PLC and decline of product qualification rate.

In recent years, the influencing factors of power quality of power grid mainly include:

With the wide application of power electronic technology, the electrical appliances in the power supply system are becoming more and more popular with the change of power load structure. The nonlinear, impulsive and unbalanced power consumption characteristics will lead to the deterioration of power quality, especially the large number of non-linear equipment put into operation.

The equipment is more and more sensitive. With the popularization of computers, the application of microelectronic control technology, and the development of automation, scale and refinement in power supply system of factories, the requirements for power quality and power supply stability are higher and higher, and the problems are more and more serious. The factory power supply has a certain impact on the power quality of the power grid, and necessary measures should be taken to deal with it, including installing on-line power quality monitoring device and installing active power filter to improve power quality.