Demand side management in hybrid rooftop photovoltaic integrated smart nano grid

Abstract

The unfettered rise in electricity demand due to overpopulation, industrialization, and lack of adequate generation augment stress on utilities’ ability to serve their customers. The situation usually worsens when the demand exceeds production. The peak demands are catered by operating expensive spinning reserves or resort to blanket load shedding by utilities during the peak hours. The first option increases the cost of electricity which is undesirable whereas indiscriminate load shedding is also unacceptable. Utility companies practice direct control methods such as utility integrated control over consumer loads during peak hours to minimize the gap between supply and demand. We present a frequency and voltage relaying based demand side management (DSM) scheme to reduce the load on 11 kV distribution feeders during peak hours without resorting to blanket load shedding. In this scheme, an energy management system (EMS) employing Underfrequency and Undervoltage (UFUV) relays is implemented at consumers’ premises instead of 220 kV distribution substations stations. This system monitors the power system’s vital signals, voltage and frequency, to manage load. The EMS controller automatically detects the frequency and voltage changes in the system and responds to respective loading patterns. The dynamic voltage (v), current (i) and frequency (f) signals are acquired from zero crossing detectors and power sources are analyzed and stored. The transducer with output voltage range in millivolt (mv), signal conditioning techniques are applied to match data acquisition range (0–10V). The predefined range are computed with dynamic values to send tripping signal to control device. In order to counter sag, swell or minor deviation a 2–3 cycles time delay is added in calculations. The integration of the proposed DSM system has shown up to 97% power supply reliability. Efficient energy management reduces Green House Gas (GHG) emissions, which is a significant step towards cleaner production.