An approach to control a photovoltaic generator to damp low frequency oscillations in an emerging distribution system

Factors like diminishing fossil fuels and environmental concerns are driving the integration of locally available energy resources at a distribution level. As a result, a number of stability issues have become a concern for utilities at distribution systems. One of the important stability concerns is the small signal stability caused by electromechanical or other low frequency oscillations. The oscillations with lower values of frequency and damping may cause instabilities. In such cases, a suitable control methodology must be applied to ensure the stability of an emerging distribution system. In this paper, a methodology to control the power factor of photovoltaic generator (PV) is proposed for enhancement of system stability. The impact of PV power factor control on a low damped mode is assessed by using both eigenvalue sensitivity and time domain analysis. An appropriate signal for the proposed controller is identified by residue technique. The effectiveness of the controller is tested in IEEE 43 bus test distribution system with distributed generators. Results show that reactive power support from PV is better for damping of critical mode.