Reactive Power Compensation Tips

When the load of the power grid is inductive, such as electric motors, welding machines, etc., the current of the power grid lags behind the voltage by an angle. When the load is capacitive, such as overcompensation state, the current of the power grid leads the voltage by an angle. Power factor lead or lag refers to the phase relationship between current and voltage. The controller of the compensation device detects the physical quantity of the power supply system to determine the switching of capacitors, which can be power factor or reactive current or reactive power.
Below is an example of power factor type. When this physical quantity meets the requirements, such as cos Φ leading and>0.98, lagging and>0.95, within this range, the controller does not send out any control signal, and the capacitor banks that have been put into operation do not exit, nor do the capacitor banks that have not been put into operation. When cos Φ does not meet the requirements, such as cos Φ lagging and<0.95, a set of capacitors will be put into operation, and if cos Φ still does not meet the requirements, the controller will delay for a period of time (the delay time can be set), and then another set of capacitors will be put into operation until all capacitors are put into operation. When a leading signal such as cos Φ<0.98 is detected, indicating a capacitive load, the controller will cut off the capacitor banks one by one. The principle to follow is that the first capacitor bank to be put into operation must be cut off before being cut off. If the delay time is set to 300s and this compensation device has ten capacitor banks, then the total input time is 5 minutes, and the same goes for cutting off. During this period, reactive power loss compensation can only be gradually implemented. If the delay time is set very short or not set, this situation may occur. When the controller detects cos Φ<0.95, it quickly turns on the capacitor banks one by one. During the input period, the power grid may already be a capacitive load, which is overcompensated. The controller then controls the capacitor banks to be cut off one by one, repeating the cycle and causing oscillation, leading to system collapse. Whether oscillation can be formed is closely related to the nature of the load, so this parameter needs to be adjusted according to the on-site situation, and the compensation effect should be considered while ensuring system safety.