Locational Aspects of Distributed Generation. Locational Aspects of Distributed Generation PSERC. Fernando L. Alvarado

Transcription

1 Slides to be available from Locational Aspects of Distributed Generation Fernando L. Alvarado The University of Wisconsin IEEE/PES Winter Meeting Columbus, Ohio, 31 January 2001 PSERC

2 Distributed Generation Very small generators at end-user sites Cogeneration plants and CHP units Large generators near loads Standby and emergency generators operated as needed Renewable systems at user locations Disconnectable load with standby power

3 While distributed generation may in and of itself become a dominant force in the provision of energy, it is its capability to be used in numerous locations and become integrated into the grid that potentially gives it its greatest value.

4 Distributed generation attributes Enables some generation technologies Provides ancillary services, such as voltage regulation and reserves Can recover heat and improve efficiency Leads to higher level of user reliability Can improve grid reliability as well Enables customer differentiation according to reliability needs

5 Why distributed generation now? The need for quality and reliability The economics work in some cases Cheap Natural Gas? Progress in small-scale generation Deregulation Difficulties siting large plants and transmission lines The need for sustainability

6 The sustainable technologies Technology Nuclear Coal Hydro Photovoltaic Wind Biomass Geothermal Gas turbines/fuel cells Central or distributed Central Central Dispersed but remote Dispersed low density Dispersed low density It depends, low density Central Dispersed or central

7 DG attributes Technology Hydro Photovoltaic, wind Gas turbines/fuel cells Attribute Energy constrained, available on demand, location restricted Location restricted, intermittent, not available on demand Available on demand, less restricted on location

8 Distributed generation issues Multiple reasons for use System reliability Lower cost Integration of renewables Local power quality Location matters Some locations more valuable than others Some locations more suitable for production than others

9 Determining the value of location System reliability: sensitivity of the loading margin to a change in supply Highest sensitivity locations are better candidates from the reliability viewpoint Don t forget the value of reactive power Economics: nodal price characteristics Only if spatial pricing is in effect Quality: voltage regulation, sag control, end-user reliability

10 System reliability Determine nature of reliability problem Overload Voltage (magnitude or flicker) Insufficiency of generation Determine severity of problem (margin) Determine impact of location on margin Incentivize accordingly

11 Margin Sensitivity Information Location Sensitivity (MW-margin per MW) A 0.46 B 1.94 C 0.62 There is a lot more on the topic of margin sensitivity Look at PSerc Web site, work by Scott Greene

12 Value of a distributed resource Energy value Reserves and system reliability value Power Quality benefits Reduction in the Value of Lost Load Better end-user reliability

13 Importance of location on price One region, 2 locations, four weeks

14 Importance of location on price Three regions, one year, average monthly prices

15 Fuel characteristics Intermittent technologies: match need to supply characteristics Ramping rate is important Must match to volatility of price Must consider the rules of the location

16 Power quality issues Unless redundancy is provided, stand-alone DG may lower reliability Grid can add reliability Utilization factor of grid connection low Depending on the technology used, harmonics and voltage control can improve or deteriorate For disconnected operation, frequency control becomes a big issue

17 Principles for siting Determine requirements of the site Value of energy to user Value of reliability to user Value of power quality to user Determine localized needs of the grid Local price of energy Grid reliability margin and impact of location Determine the attributes of the distributed generator Intermittent or available on demand Energy constrained or not Response time characteristics

18 Conclusions DG resources are best if integration into the grid is an option It is necessary to match the needs of the energy user, the production technology, and the grid at the location