On power quality and reliability of supply

Abstract

Abstract. Power quality determines reliability of electrical equipment operation, performance of the assigned functions by it, service life. In the last years problem of power quality attracted increased attention because of power quality degradation and a great number of consumer complaints. Many problems of power quality control, such as determination of liabilities and responsibility of power suppliers and consumers for its quality, call for solution. The paper presents the types of damages caused by harmonics and the results of an analysis of harmonic active power at the node connecting an aluminum smelter block to a supply network. The analysis is performed on the basis of measurements. Measured current and voltage were used to calculate harmonic active power. It was found out that the aluminum smelter block generates the harmonic active power to the supply network only during part of the measurement time. For the other part harmonic active power flows from the supply network to the aluminum smelter block. The paper presents the proposals on the use of harmonic active energy for determination of the power quality distortion source and its contribution.

Distortion Load Identification Based on the Application of Compensating Devices

“…It is known that disturbances of the power quality indicators can occur both due to the fault of consumer and due to the work of third-party energy objects connected to the same point of common coupling (PCC) of the electrical grid. In this case, it is difficult to determine the exact location of the distortion source and its contribution to standardized indicators, for example, to the voltage total harmonic distortion factor (THD U ) [7,8].…”

“…The most well-established and frequently methods mentioned in the literature are the methods based on analysis of the Norton or Thevenin equivalent circuits [16][17][18] and the active power flow of harmonics [8,19].…”

“…The second approach involves determining the direction of the active power flow at harmonics. It is based on the measurement of the values of active power at harmonics [8,19]. The method has a practical application, but does not always yield correct results.…”

“…It should be noted that, in Russian power quality standards, there is only a limitation with respect to high harmonics in voltage. However, disturbances of the standard requirements are massive and systematic in many power systems [8]. One of the reasons is the lack of regulations in the area of limiting harmonic currents from consumers and evaluating their influence on voltage distortions.…”

Measurement of currents and voltages non-sinusoidal parameters in power supply systems with rectifier load

“…Non-sinusoidal voltage is characterized by the voltage subgroup harmonic distortions KU(n) and the voltage subgroup total harmonic distortions (THDS) KU.. The results of the assessment of the power quality state in the electrical grids of the Russian Power System confirm that the highest levels of harmonic distortions are observed in electric grids feeding the electrified railway, oil and gas transportation and mining enterprises, metallurgical and aluminum enterprises [2][3][4][5].…”