Techno-economic analysis of harmonic disturbances in a university environment: a case Study at the University of Cape Coast

Abstract

Nonlinear electrical loads connected to the power grid have increased within the past decade and estimated to reach 95% of all connected electrical loads in the coming decade. However, these loads are major sources of harmonics. Direct linkage could be established between the adverse effects of harmonics and avoidable costs as utilities and consumers alike are recording rather huge loss of revenues globally as a result of harmonic disturbances. In Ghana and at the University of Cape Coast, the proliferation of these nonlinear loads, owing to nonexistent standards to curb the influx, has led to high harmonic distortions on the distribution network and the attendant disturbances is evident. Problems of harmonics in the University are presented in the form of frequent fusing of CFLs, LEDs, botching of all capacitor types, including PF correction capacitors. This has necessitated rampant replacements of the aforementioned and other susceptible loads at huge economic expense to the University. This research investigates the adverse impact of harmonic disturbances present in the electrical installations and distribution network of the University of Cape Coast in economic terms. Modelling and simulation of the electrical distribution system was carried out using Electrical Transient and Analysis Program (ETAP) software, which was able to extract harmonic waveforms and spectrums. Power quality analyser, using the “very-short time” monitoring duration and referenced against the IEEE 519-2014 harmonics standard, was also employed to obtain both the Voltage Total Harmonic Distortion (THDV) and Current Total Harmonic Distortion (THDI). The average total harmonic distortions measured at the University is 16.43% with dominant harmonics of the 3rd, 5th, 7th, 11th and 13th orders culminating in a reduced true power factor of 0.944. Analysis on the network showed a reduction of the THDI level from 16.43% to 8%. Significant improvement of the true power factor with considerable cost savings of about Gh¢1,161,493.71 per annum was realised. The installation of tuned paralleled passive filters to mitigate harmonics gave a net present value of Gh¢2,736,028.00 at a discount rate of 8% with a payback period of 6.23 years.