Application of intelligent capacitors in reactive power compensation

Intelligent capacitors are an important milestone in the development history of reactive power compensation technology in power systems. The reason why smart capacitors are called smart products is that they can be used without the support of compensation controllers. Self generated - an independent reactive power compensation system. It has zero crossing switching and automatic protection functions, which is a major breakthrough in low-voltage power reactive power automatic compensation technology. It can be flexibly applied to various occasions of low-voltage reactive power compensation, with advantages such as simple structure, low networking cost, superior performance, and easy maintenance.

The switching switch in smart capacitors has a special electromagnetic zero crossing switching technology, with a zero crossing switching offset of less than 2.5. The switching inrush current is less than 2.5 times the rated current. The intelligent control unit controls the voltage at both ends of the switching switch to close at the zero crossing point by detecting the voltage when the dynamic and static contacts of the switching switch are disconnected. By detecting the current when the dynamic and static contacts of the switching switch are closed, it controls the current to open at the zero crossing point, achieving the "zero crossing switching" function, so that the inrush current generated when the low-voltage power capacitor is put into operation is very small, and there is no arcing phenomenon when the low-voltage power capacitor is withdrawn. This extends the lifespan of low-voltage power capacitors and switching devices themselves. It also reduces the impact of switching devices on the power grid and improves the power quality of the grid.

When intelligent capacitors are used in multiple online systems to form a reactive power compensation system, they can automatically generate one master and the rest as slaves, forming a low-voltage reactive power compensation system that automatically controls its operation; Individual slave machines can automatically shut down in case of malfunction, without affecting the normal operation of other smart capacitors; After the host fails and automatically exits, a new host is automatically generated from the other slave machines to form a new system that works normally; Capacitors with the same capacity are switched according to the cyclic switching principle, while capacitors with different capacities are switched according to the capacity compensation principle to ensure no oscillation during switching.

In the case of unbalanced three-phase loads in the power grid, smart capacitors can adopt a combination of three-phase common compensation and three-phase partial compensation. According to the magnitude of the reactive power deficit in each phase, capacitors can be switched to compensate for the three-phase power supply separately, achieving the effect of reactive power compensation.

Intelligent capacitors have their own operation panel and LCD display with complete and complete data display, including distribution voltage, distribution current, distribution power factor, operating current of the intelligent capacitor itself, temperature inside the capacitor shell, etc.

The protection functions of intelligent power capacitors include: distribution overvoltage, undervoltage, loss of voltage, and phase loss protection; Over temperature protection at the power supply inlet end; Segmented overcurrent protection for each phase of power capacitors; Internal over temperature segmented protection of power capacitors.

Intelligent capacitors have human-machine dialogue function. This is also an important technical means for operation and maintenance personnel to operate, debug, and maintain smart capacitors. Only through human-machine dialogue can smart capacitors be controlled correctly.