Study on Controlling Power Quality Based on Thermodynamics Modeling Method for 6.3kV Power System - Intelligent Computing for Sustainable Energy and Environment - page 3

Fig. 1. Topology of distribution substation of a Coal Mine

In order to solve the power quality problems in power system it is necessary to
monitor and analyze actual harmonics and reactive power firstly. For this purpose, the
reactive power, harmonic current of the secondary side of the transformer are
obtained by HIOKI power quality analyzer 3196 in July 14 th , 2009.
Figure2 and Table 1 show the max current of 5 th , 7 th , 11 th and 13 th harmonic order
of the 6.3kV power system. It indicates the 5 th harmonic current reached 111.60A
which far exceeds 63.04A that allowed by the national standard GB/T-14549-93.

Fig. 2. The harmonic current of 6.3KV bus

Table 1. Measured harmonic current of 6.3KV bus (A)

harmonic current

harmonic order 5 7 11 13

allowed value 63.04 44.50 29.66 29.66

average values 11.40 10.80 7.00

111.60

Figure2 to Figure4 show that there are more surge current and voltage flash of
6.3kV bus. These phenomena can be illustrated by Figure4. Due to there were 2 banks
of fixed capacitor which capacity of 6600kVar maximum power factor of 6.3kV bus
reached 0.98 almost.