Interconnecting Industrial DG to the Main Grid
Dr. Mithulananthan Nadarajah Energy Field of Study Asian Institute of Technology
Introduction of DG Benefits Interconnection Issues Technical Issues Commercial and Regulatory Issues Other Issues Conclusion
Distributed Generation (DG)
Distributed generation is not a new concept. In fact,the history of power generation started with the distributed generation. Early power plant only supplied electricity to customers in its close neighbourhood. In the last decade, technological innovations, changing economy and environment concern have resulted in a renewed interest in distributed generation. The ‘economy of scale’ in power industry has shrunk in the recent years and utilitygeneration pattern is shifting from ‘economy of scale’ to ‘economy of mass production’ Recent studies suggest that the difference in cost of electricity production (cost per kWh) between large and small scale generation has reduced to 30% in 2000 from 60% in 1960. Due to these and various other reasons including environmental concern, distributed generation are gaining popularity around the globe.Definition of DG
Distributed generation in simple term can be defined as a small scale generation. It is active power generating unit that is connected at distribution level. IEEE defines the generation of electricity by facilities sufficiently smaller than central plants, usually 10 MW or less, so as to allow interconnection at nearly any point in the power system, as Distributed Resources. ElectricPower Research Institute (EPRI) defines distributed generation as generation from a few kilowatts up to 50 MW. International Energy Agency (IEA) defines DG as “Power generation equipment and system used generally at distribution levels and where the power is mainly used locally on site”. The International Council on Large Electricity Systems (CIGRE) defines DG as generation that is not centrallyplanned, centrally dispatched at present, usually connected to the distribution network, and smaller than 50-100 MW.
Present and Future Distribution System
Fig 1: Changing Distribution Structure (Source: Distributed Utility Associates)
Reciprocating Engines Photovoltaic Wind Power Fuel Cells Micro-Turbines Reciprocating Engines Combined Heat and Power Plants (CHP) BagasseFired Plants
Driving Forces of DG
IEA (2002) has listed five major reasons why we should choose distributed generation: Developments in distributed generation technologies Constraints on the construction of new transmission lines Increased customer demand for highly reliable electricity Electricity market liberalization Concerns about climate change Other driving forces are: Reduction ofoverall cost to electricity consumers Need for increased generation capacity Need for improved reliability Need for increased security Need to respond to demand peaks
DG in Sugar Industry
Fig 2: Schematic diagram of a Bagasse-fired plant for combined heat and power production (Source: Williams and Larson, 1993)
Benefits of DG to Industries
Increased reliability: Installation of DG in theindustry’s backward will improve the reliability of the power supply. Industry can have “Uninterrupted Service” by installing a DG where it can be used as the backup to the main grid. Power quality: Many types of electrical equipments are very sensitive to voltage and frequency. With DG, industry can have a micro-grid operation to prevent its equipment from voltage sag and swells as well asdeviation of frequency. Energy cost savings: Cost of energy is increasing with increasing fuel price and industries have to pay heavy demand charges. Industry can save the energy cost by running the DG at peak load. Depending on the technology and fuel cost, sometime generating energy from DG is less costly than buying from grid.
Benefits of DG to the Industry (2)
Increased energy efficiency:...