Research into harmonic power in the high- voltage networks

Abstract

Abstract. The paper presents the results of studies on the harmonic active and reactive power at nodes of 110 kV and 220 kV networks. The studies were based on the measurements made at the node of 110 kV network supplying power to an aluminum plant and at the node of 220 kV network supplying power to railway traction substation. The supply networks belong to the Unified Energy Systems of Russia. Many other facilities with high-power nonlinear loads receive electric energy from these networks. They make their contribution to the formation of harmonic conditions across the networks. The measurements of currents and voltages were used to calculate active and reactive power for harmonics 2-40. The calculations show that although the considered facilities are the sources of harmonics and generate harmonic power to the supply networks they also receive harmonic power from them. The harmonic active power flows change directions during the measurements. Their values vary in a wide range and can reach several tens of kilowatts. The values of harmonic reactive power also vary in a wide range. They change the direction of the flow and affect the values of voltage, as a rule, at the characteristic harmonics of the nonlinear electrical equipment.

Specific Features of Harmonic Conditions at the Node Connecting a Pulp-And-Paper Mill to a Supply Network

“…In the last decade intensive measurements of harmonics parameters have been continued, which is explained by the emergence and widespread use of new nonlinear electric equipment and increase in the values of current and voltage harmonics in the networks. For example, the results of measurements at the network node supplying the nonlinear loads of the retransmission TV stations are presented in [8]; the results of measured parameters of the harmonics generated by energy saving lamps are presented in [9]; the harmonics measured in the medical center and their impact on the work of the medical equipment are indicated in [10]; the results of large-scale measurements of power quality indices in the 110 kV networks of Siberia, which cover 23% of Russia's territory, are demonstrated in [11]; the results of the studies on parameters of harmonics for the complex loads connected to the nodes of the 110-220 kV networks are presented in [12]; the results of an analysis of harmonic active power of high-power nonlinear loads connected to the 110-220 kV networks are given in [13]. The measurements confirmed the presence of harmonics in the electrical networks.…”

Modeling of nonlinear loads in high-voltage network by measured parameters

“…The previous analysis of measured data in [2], [6]- [8] shows that modeling a nonlinear load should include two stages:…”

“…For reactive current we assume the same direction as for reactive power in [11], provided the load is inductive. Active and reactive currents are directed from network to load if angle In [8] based on the analysis of measurements we obtained that at one and the same time instant active power of different harmonics can have opposite directions. This conclusion applies to currents as well.…”

“…Duration of measurements should be determined individually for each certain case. Since the parameters of harmonic conditions in high-voltage networks vary randomly [6]- [8] it is necessary to analyze them by the methods of mathematical statistics.…”