IMPROVING THE QUALITY OF POWER SUPPLY IN MARYLAND 11KV DISTRIBUTION NETWORK USING PASSIVE HARMONIC FILTERING SCHEME

Subject Area: POWER SYSTEM

This paper presents improving the quality of power supply in 0.75MVA, Maryland 33/11kv distribution network using passive harmonic filtering scheme. The aim is to improve the quality of power supply which has been impacted by the effect of harmonics. To achieve this aim, the case study transformer was characterized and the harmonics percentage was determined as 14.17% which is not good as it did not satisfy the requirement for Nigerian Electricity Regulation Commission (NERC) which required tolerance of 5% as maximum for harmonics in distribution transformers. The study utilized passive filter which used single tuned, double tuned, high pass and C-type filter to mitigate harmonics from the 3rd to 24th order. The filter was implemented on the 33/11KV transformer using simulation and then tested. The result showed that harmonics was mitigated to 0.01394% which is good as it satisfied the NERC standard requirements. The filter was then integrated on the distribution transformer and tested for consecutive 19 hours on load. The result showed that the harmonics percentage is 7.8%. The implication o the result showed that it did not satisfy the requirements of the NERC and IEEE for harmonics mitigation power system network. The reason was due to the old age of the transformer and poor maintenance factor which has seriously affected the reliability of the system. However, the transformer with the passive filter connected to it was able to achieved better quality of power supply with harmonic reduction from 14.17% to 7.8% which gives a percentage improvement in quality of power supply at 44.95%.