Most compensation banks are controlled stepwise. For this purpose it is essential to ‘know’ when it is allowed to (de)activate a capacitor step by the power factor relay. The so-called C/k value is calculated by the step size C divided by the ratio k of the current transformer.
Thus the number of capacitors is identical to the number of steps: six capacitors controlled by six steps. However, compensation banks with unequal steps, for example 50 kvar and 25 kvar (see Figure 1), enable compensation in ‘fine-stepping’ mode.
This paper intensively studies the proposed solution using capacitor current ramp compensation, which is a superior solution featuring fast response and universality. A frequency-domain small-signal model based on describing function method is proposed in this paper. The time-domain large-signal response to the load step change is analyzed.
Depending on the size of a compensation unit, it is assembled with capacitors of equal size (in bigger units) or of different size. A unit with a total reactive power of, for example, 300 kvar consists of six power capacitors, of 50 kvar each. Thus the number of capacitors is identical to the number of steps: six capacitors controlled by six steps.
The analysis illustrates the unique transient response behaviors of the capacitor current ramp compensated V 2 control. The design optimization methodology based on frequency-domain and time-domain analysis is presented. The proposed model and the design guidelines are verified by the experimental results.
The concept of the degree of rate control is useful in several ways. First, it quantifies concepts like the rate-determining step. In cases where one well-defined reaction step is the most difficult, the XRC value of that transition state energy is 1, and all other values are 0.