Analysis of voltage quality parameters in MV distribution grid

Abstract

This paper describes the impact of operation of big customers on voltage quality parameters in medium voltage distribution grids. The survey is based on the evaluation of 45 voltage quality measurements which were carried out in 15 different delivery points of other customers. These 45 measurements were made in years 2014, 2015 and 2016 (15 measurements a year) and were evaluated according to standard EN 50160. The impact on voltage variations and other voltage quality parameters was analysed.

Instrument Transformers for Power Quality Measurements: a Review of Literature and Standards

“…The limit set by the standard [14] for the k u factor is 2 %. In [10], all the measured k u values are in the range between 0.1 % and 0.7 %. In [15], PQ is monitored in substations and distribution feeders at various voltage levels (from 13.8 kV to 138 kV).…”

“…It has been found that the P lt index quite often exceeds the limit set by standard [17] and the maximum observed value is 1.7. In [10], the maximum observed P lt is 2.5 and the corresponding P st is equal to 3. In [11], P lt ranges from 1.35 to 3.53.…”

“…Supply Voltage Deviation. In [10], 15 different MV (20 kV) supply points are analyzed over 3 years (2014-2016) and the recorded voltage variations range from 96.6 % to 107.3 %. In [11] the maximum voltage reaches the value of 108 % of the nominal voltage U n (20 kV).…”

“…The harmonic disturbance can be analyzed in two different ways, i.e., the amplitude level of single harmonic tones and the total harmonic distortion (THD). In [10], the THD measured values are far below the limit set by the standard [14] and they range from 1.5 % to 6 % with a mean value of 2 %. The same paper focuses on the 3 rd , 5 th , 7 th and 15 th harmonic; all the harmonic amplitudes are well below the standard limit [14], except for the 5 th harmonic that reaches the 6 % limit but does not exceed it.…”

Evaluation of Harmonics Impact on Digital Relays

“…Based on previous reports [21,22], the total harmonic distortion was measured at 30 different grids in the Czech Republic at different intervals. The measurements and evaluation of the harmonic level were made by the E.ON Distribution in the Czech Republic, operated by the company E.ON Czech Republic.…”