Capacitor compensation is like adding a little helper to the circuit, making the current transmission more efficient. In DC transmission, the wires themselves have resistance, which will cause the voltage to become lower. In AC circuits, some devices (such as motors) will make the current and voltage out of sync, resulting in power waste. Capacitors are like a small reservoir that can charge and discharge quickly. In AC circuits, the resistance to current is very small and can respond quickly to current changes; but in DC circuits, they are like a barrier that prevents current from passing.
So why do low-voltage cabinets need capacitor compensation? This is because many of the equipment in the low-voltage cabinet are inductive loads (such as motors, transformers, etc.), which will reduce the power factor of the circuit, causing power waste and equipment heating. By adding capacitors for compensation, the power factor of the entire system can be improved, power loss can be reduced, equipment life can be extended, and electricity bills can be saved.
✔ How does power capacitor achieve compensation?
In principle, a capacitor is equivalent to a generator that generates capacitive reactive current. The principle of reactive power compensation is to connect a device with a capacitive power load and an inductive power load in parallel to the same capacitor, and the energy is converted between the two loads. In this way, the load on the transformer and transmission line in the power grid is reduced, thereby increasing the output power.
When a certain active power is output, the loss of the power supply system is reduced. In comparison, capacitors are the simplest and most economical way to reduce the load on transformers, power supply systems and industrial distribution. Therefore, it is imperative to use capacitors as reactive power compensation for power systems. At present, the use of parallel capacitors as reactive power compensation devices has become very common.
✔ What are the characteristics of power capacitor compensation?
Advantages: The reactive power compensation device of power capacitors is easy to install and the installation location can be easily increased or decreased; the active power loss is small (only about 0.4% of the rated capacity); the construction period is short; the investment is small; there are no rotating parts, and the operation and maintenance are simple; the damage of individual capacitor groups will not affect the operation of the entire capacitor group, etc.
Disadvantages: The disadvantages of the reactive power compensation device of power capacitors are: only step-by-step adjustment is possible, not smooth adjustment; poor ventilation, once the operating temperature of the capacitor is higher than 70°C, it is prone to expansion and explosion; poor voltage characteristics, poor short-circuit stability, and residual charge after removal; low reactive power compensation accuracy, which can easily affect the compensation effect; difficult operation and management of compensation capacitors, and the problem of safe operation of capacitors has not been taken seriously, etc.