Views: 2 Author: Site Editor Publish Time: 2018-07-27 Origin: Site
What is the parallel capacitor bank wiring:
The wiring of capacitors is usually divided into triangle and star. In addition, there are double triangles and double stars.
The triangular-connected capacitor directly withstands the line-to-line voltage. When any capacitor is broken down due to a fault, a two-phase short circuit is formed, and the fault current is large. If the fault cannot be quickly removed, the fault current and the arc will cause the insulating medium to decompose to generate gas. Explosion of the fuel tank and the spread of adjacent capacitors. This wiring is therefore rarely used in 10kV systems, but is used in small quantities in 380V distribution systems.
In the high-voltage power network, the star-connected capacitor bank is widely used at home and abroad. The inter-electrode voltage of the star-connected capacitor is the phase voltage of the grid, the insulation is subjected to a lower voltage, and the capacitor is designed to have a lower field strength. When one capacitor in the capacitor bank is short-circuited due to a fault, the fault current will be reduced to a certain range due to the impedance limitation of the remaining two healthy phases, and the fault effect will be alleviated.
The star-connected capacitor bank structure is relatively simple and clear, and the construction cost is economical. When applied to a higher voltage level, this wiring is more advantageous.
The biggest advantage of star wiring is that you can choose from a variety of protection methods. After a few capacitor faults break through the short circuit, a single protective fuse can quickly remove the faulty capacitor without causing the capacitor to explode. Due to the above advantages, star-shaped wiring is now commonly used for high voltage capacitor banks of various voltage levels.
In addition to star-shaped wiring, the double-star wiring is widely used in capacitor banks of high-voltage power systems. The so-called double star connection is to divide the capacitor into two star-connected capacitor banks with equal or similar capacitances, which are connected in parallel to the grid bus. The neutral points of the two sets of capacitors are connected by a low-ratio current transformer. .
1. Parallel capacitor bank basic wiring type
The basic wiring of parallel power capacitor banks is usually star. There is also a double star connection derived from the star. Each star is called an arm, and the capacitor specifications, capacitance values, and quantities of the two arms are equal.
2. Parallel capacitor bank wiring
When the rated voltage of a single parallel capacitor cannot meet the normal working voltage requirements of the power grid, two or more capacitors must be connected in series to meet the normal working voltage requirements of the power grid. In order to achieve the required reactive power compensation capacity, several capacitors are required in parallel to form a parallel capacitor bank.
The principle of internal wiring for each phase of the shunt capacitor bank is to be connected in parallel and then in series. The advantage of this wiring method is that when a fault capacitor is discharged due to the fuse blown, the phase capacity change is small, and the change of the operating voltage with other capacitors in parallel with the fault capacitor is also small.
