How to calculate the reactive power compensation capacity

Electrical is a professional manufacturer of low-voltage reactive power compensation components and harmonic control equipment. We come into contact with a large number of customers with reactive power compensation needs. Their situations can be roughly divided into two types. The first type is new projects where there are absolutely no reactive power compensation devices. The second type is renovation projects where reactive power compensation devices have already been put into operation, but due to various reasons, the power factor fails to meet the standards, and thus adjustments to the existing plan are required.

For new projects, in simple terms, the power factor without reactive power devices is unknown. Generally speaking, using method one is impossible to calculate because a known parameter is missing. Therefore, we need to introduce an empirical value. For dedicated transformer users, the power supply bureau usually stipulates that a power factor of 0.9 or above will not be subject to assessment. However, for the same 630kW transformer, the actual load of the user is different, and the configured reactive power compensation device is also different. Usually, we take 30-40% of the transformer capacity.

 

How should the reactive power compensation capacity be calculated for the renovation project?

To calculate the capacity of the reactive power compensation device, three technical parameters are usually required for the calculation;
(1) The power factor before the reactive power compensation device is not installed; it is represented by "cosφ1"
(2) The desired power factor to be increased; it is represented by "cosφ2"
(3) The active power of the dedicated transformer customer; it is represented by "P" Calculation formula

In the formula:
P: The actual active power;
Q1: The reactive power before the reactive power compensation device was installed;
Q2: The reactive power after the parallel reactive power compensation is in operation;
Qj: The reactive power that needs to be compensated;

Case:
Suppose the transformer capacity of a dedicated transformer user is 630 KVA, and the power factor is approximately 0.6 every month, resulting in the user's power factor adjustment electricity charges being evaluated. Now, it is necessary to increase the power factor to around 0.9. How large a reactive power compensation device needs to be configured?

Purpose: These calculations determine the reactive power compensation (QcQc​) needed to improve the power factor from cos⁡φ1=0.6cosφ1​=0.6 to cos⁡φ2=0.9cosφ2​=0.9.

Units:

PP (active power) in kW,

QQ (reactive power) in kvar,

SS (apparent power) in kVA.

Result: A capacitor bank of approximately 321 kvar is required for compensation.

 

The low-voltage reactive power compensation cabinet is a device used to compensate for the reactive power required by inductive loads. This device plays a crucial role in improving the power factor of the system, enhancing the quality of electrical energy, prolonging the service life of electrical equipment, reducing power grid transmission losses, and suppressing voltage fluctuations.

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