From the point of view of power supply, the ideal load is equal to P and S, and the power factor cosφ is 1. At this time, the utilization rate of power supply equipment is the highest. In fact, it is impossible. This is only possible when all the loads in the system are resistive.
Most of the electrical load devices in the circuit are inductive in nature, which leads to the total current of the system lagging behind the voltage, thus in the power factor triangle, the reactive Q side increases, the power factor decreases and the efficiency of power supply equipment decreases.
The power triangle is a right triangle, and the power consumption quality is reflected by cosφ (that is, the cosine of φ angle). A large number of inductive loads make the power equipment from power generation to power consumption in the power system not fully utilized, and a considerable part of electric energy is exchanged back and forth with user equipment through the power generation, transmission, substation and distribution system.
On the other hand, reactive power is not useless, it is a necessary condition for inductive equipment to establish magnetic field. Without reactive power, our transformers and motors can't work normally. Therefore, trying to solve the problem of reducing reactive power is the correct solution.
Extended data:
Design reference
The low-voltage capacitor compensation cabinet consists of cabinet shell, bus, circuit breaker, disconnector, thermal relay, contactor, lightning arrester, capacitor, reactor, primary and secondary wires, wiring terminals, power factor automatic compensation control device, disc instrument, etc.
The existence of nonlinear components (harmonics) in the load will cause other high-frequency (high-order harmonics) currents to flow through the capacitor circuit, which will damage the capacitor by overvoltage, overcurrent, over-capacity, over-temperature, etc. Otherwise, the capacitor bank will not be cast correctly.
In this case, in addition to using a special "filter capacitor" to increase its resistance (higher price); It is also possible to form a filter loop by selecting a suitable reactor to filter out strong higher harmonics; Choosing a capacitor with higher rated voltage is also one of the ways to reduce harmonic accidents.
For a load with a capacity of 700KW, the natural power factor can be measured first, that is, the power factor without capacitance when all loads are started. If there is no accurate measurement, it is estimated that most of your load is motor, and the power factor is estimated as cosφ 1=0.70. If you want to be in the rated state, increase its power factor to 0.90.
Reference source: Baidu Encyclopedia-Capacitance Compensation