Voltage Failures in Electrical Networks and Determination of their Characteristics

Abstract

Widespread introduction of power electronics, the growing number of non-linear consumers, and the change in the structure of electrical energy carriers have a negative impact on the quality of electrical energy. One of the most important l parameters of electrical energy quality influencing the interruptions of the operation of electrical equipment is voltage failures. Voltage failure in the electrical network is negative phenomenon that leads to an increase of electricity losses, an increase of reactive power consumption, a decrease of electric loads performance and interruptions in the operation of electrical equipment.

Main causes of voltage failures, such as overloads, short circuits, equipment malfunctions and other factors that affect the state of electrical networks and methods for determining their characteristics are analyzed.

The determination of voltage failure is often established on the basis of two parameters — magnitude/depth and duration. This determination is typical for the transient processes due to symmetrical voltage drops. But transient processes due to asymmetric voltage failures are determined not only by the values of magnitude/depth and duration, but also by the so-called point on the voltage wave where the voltage dip occurs and the change in the phase angle during the voltage dip.

Jumps in the voltage phase angle in the electrical network and the associated phase angle shift significantly affect not only the error in determining the quantitative and qualitative parameters of electrical energy, but are also a problem for power electronics that use phase switching or voltage crossing through zero.

The determination of the phase angle is analyzed on the example of the presence of a short circuit in the radial electrical network. The expediency of determining the main characteristics of voltage dips in electrical networks is highlighted and the most suitable methods are analyzed.