Method and system for determining a capacitance value

A method for determining a capacitance value of a capacitor, the method comprising:

• measuring, by a current sensor, a current signal flowing through the capacitor;
• receiving, from the current sensor, the current signal flowing through the capacitor;
• measuring, by a voltage sensor, a voltage signal applied across the capacitor;
• receiving, from the voltage sensor, the voltage signal applied across the capacitor;
• receiving, by a first low pass filter connected to the current sensor, the current signal;
• filtering, by the first low pass filter, the received voltage signal at a dominant frequency, wherein the dominant frequency is a frequency with a maximum amplitude, and wherein the first low pass filter attenuates current signals with frequencies higher than the dominant frequency;
• receiving, by a second low pass filter connected to the voltage sensor, the voltage signal;
• filtering, by the second low pass filter, the received current signal at the dominant frequency, wherein the second low pass filter attenuates voltage signals with frequencies higher than the dominant frequency;
• sampling, by a sampler connected to the first low pass filter and the second low pass filter, each of the filtered voltage signal and the filtered current signal;
• performing a fast Fourier transform of each of the sampled voltage signal and the sampled current signal, wherein performing the fast Fourier transform for each of the filtered voltage signal and the filtered current signal comprises measuring a value of the current signal and the voltage signal over a sampling interval;
• transforming each of the discretized voltage signal and the discretized current signal into frequency domain, wherein transforming each of the discretized voltage signal and the discretized current signal into frequency domain comprises determining currents and voltages present in each of the discretized voltage signal and the discretized current signal at different frequencies
• determining an impedance of the capacitor from the transformed voltage signal and the transformed current signal;
• determining a capacitive reactance of the capacitor from an imaginary part of the impedance;
• and
• determining the capacitance value of the capacitor from the capacitive reactance.