Harmonic disturbance identification in electrical systems with capacitor banks

The identification of distortion sources in a power system is an unsolved topic. The problem is difficult to solve because there are elements in the system that do not produce harmonics but amplify those already present in the electrical network. The most common of these elements is the capacitor, which is widely used to compensate for the power factor at the fundamental frequency. The capacitor behaviour makes the indices proposed up until now to identify distortion sources fail in the presence of this element. This paper presents a new index: the load characterization index. Besides using an extended equivalent circuit to represent the load, this index calculates the distortion introduced by the load, evaluating, in addition to the current distortion at its input, the voltage distortion at its terminals. The introduction of voltage assessment makes the index suitable for identifying the linear and non-linear loads in the power system even in the presence of capacitors and from only the voltage and current measured at the point of common coupling.

► The presence of capacitor is analyzed into the identification of distortion sources in a power system.
► The load characterization index (LCI) is proposed.
► LCI is able to distinguish the linear and non-linear loads only from the voltage and current measured at the input of the load.
► Simulation and experimental tests prove the LCI validity.