1. Campus da FEUP Rua Dr. Roberto Frias, 378 4200 - 465 Porto Portugal T +351 222 094 000 F +351 222 094 050 jpl@fe.up.pt © 2009 Decentralised Energy Systems in Developing Countries J. A. Peças Lopes September 10th, 2009

2. © 2006 2 Electrical Systems in Developing Countries Small isolated electrical grids fed by small power stations frequently with small Diesel units are frequent. –These grids correspond often to a small geographical area where a population nucleus is located. –Large distances among the load centres makes unfeasible the development of interconnected electrical grids. –Reliability is week and electricity is present only a few hours per day. A change is required to improve quality of life Small isolated electrical grids fed by small power stations frequently with small Diesel units are frequent. –These grids correspond often to a small geographical area where a population nucleus is located. –Large distances among the load centres makes unfeasible the development of interconnected electrical grids. –Reliability is week and electricity is present only a few hours per day. A change is required to improve quality of life

3. © 2006 3 Selecting Renewable Generation Technologies The selection of the renewable energy technologies to be used for generating electricity in remote areas can be made using GIS: –Availability of the resources –Costs of installation –Costs of transportation The selection of the renewable energy technologies to be used for generating electricity in remote areas can be made using GIS: –Availability of the resources –Costs of installation –Costs of transportation

4. © 2006 4 Developing Countries: New paradigms are under development

5. © 2006 5 Developing Countries: New paradigms are under development The change of paradigm that DG introduced started at HV and MV level DG units have been operated without any control, injecting active and reactive power in the grid.

6. © 2006 6 DG Technologies Distributed Generation (DG) has attained a considerable penetration level in HV and MV networks, involving different types of sources and conversion technologies; –The most relevant ones are: Mini-hydro using synchronous or asynchronous generators; Cogeneration using mainly synchronous units; Biomass generation units with synchronous generators; Wind generation, using conventional asynchronous or DFIM units and synchronous machines with electronic converters. –Usually these generation devices do not participate in voltage control and frequency regulation Distributed Generation (DG) has attained a considerable penetration level in HV and MV networks, involving different types of sources and conversion technologies; –The most relevant ones are: Mini-hydro using synchronous or asynchronous generators; Cogeneration using mainly synchronous units; Biomass generation units with synchronous generators; Wind generation, using conventional asynchronous or DFIM units and synchronous machines with electronic converters. –Usually these generation devices do not participate in voltage control and frequency regulation

7. © 2006 7 DG Technologies Microgeneration directly connected to the LV network is becoming a reality: –Next 10 years: The change that occurred in MV networks will also happen in LV networks: –Connection of small modular generation sources; –Typically in the range from 5 to 100 kW; –Fuel cells, renewable generation (wind turbines and PV systems), micro turbines (natural gas or bio fuels), micro-CHP; LV networks are also becoming active; Microgeneration directly connected to the LV network is becoming a reality: –Next 10 years: The change that occurred in MV networks will also happen in LV networks: –Connection of small modular generation sources; –Typically in the range from 5 to 100 kW; –Fuel cells, renewable generation (wind turbines and PV systems), micro turbines (natural gas or bio fuels), micro-CHP; LV networks are also becoming active;

8. © 2006 88 PV Wind Gen MicroGrid: A Flexible Cell of the Electric Power System Microturbine Fuel Cell Storage Device MGCC MC LC MG Hierarchical Control: MGCC, LC, MC Communication infrastructure

9. © 2006 9 Microgeneration technologies: Micro-wind turbines

10. © 2006 10 Microgeneration - Solar Photovoltaic (PV)

11. © 2006 11 Energy storage – flywheels or batteries

12. © 2006 12 Dynamic Modelling of Components – Inverters Inverter Control Modes –PQ control Designed for grid-connected operation The inverter is controlled to meet an active and reactive power set-point Inverter Control Modes –PQ control Designed for grid-connected operation The inverter is controlled to meet an active and reactive power set-point

13. © 2006 13 Dynamic Modelling of Components – Inverters Inverter Control Modes –Voltage Source Inverter Control - VSI Designed for standalone operation (however, in some cases, grid-connected operation is also possible) The inverter “feeds” the load with pre-defined values for voltage and frequency Inverter Control Modes –Voltage Source Inverter Control - VSI Designed for standalone operation (however, in some cases, grid-connected operation is also possible) The inverter “feeds” the load with pre-defined values for voltage and frequency

14. © 2006 14 MicroGrid Operation and Control Control Modes for MG Islanded Operation –Energy storage is required to balance local load and generation in the moments subsequent to transients (disconnection of the MV network or load following during islanding operation) aiming voltage and frequency control. –Combining Inverter Control Modes, two control strategies are possible: Single Master Operation Multi Master Operation Control Modes for MG Islanded Operation –Energy storage is required to balance local load and generation in the moments subsequent to transients (disconnection of the MV network or load following during islanding operation) aiming voltage and frequency control. –Combining Inverter Control Modes, two control strategies are possible: Single Master Operation Multi Master Operation

15. © 2006 15 MicroGrid Operation and Control Storage device’s active power output is proportional to the MG frequency deviation (droop control) Correct permanent frequency deviations during islanding operation

16. © 2006 16 MicroGrids Dynamic Simulation – Test System

17. © 2006 17 Results from Simulations MG Frequency and VSI Active Power Load shedding Load reconnection

18. © 2006 18 Using MicroGrids for Service Restoration DG maturation can offer ancillary services, such as the provision of Black Start in low voltage grids Black-Start is a sequence of events controlled by a set of rules –A set of rules and conditions are identified in advance and embedded in MGCC software –These rules and conditions define a sequence of control actions to be carried out during the restoration stages Increased reliability DG maturation can offer ancillary services, such as the provision of Black Start in low voltage grids Black-Start is a sequence of events controlled by a set of rules –A set of rules and conditions are identified in advance and embedded in MGCC software –These rules and conditions define a sequence of control actions to be carried out during the restoration stages Increased reliability

19. © 2006 19 Growing the system With microgrids and DG Increase reliability to end user consumers  increase consumption levels (lighting, refrigerators, TV set, …) Interconnect nearby systems and define common operating strategies that improve economics and global reliability Introduce more renewable power sources With microgrids and DG Increase reliability to end user consumers  increase consumption levels (lighting, refrigerators, TV set, …) Interconnect nearby systems and define common operating strategies that improve economics and global reliability Introduce more renewable power sources

20. © 2006 20 Integrating Wind Power and other intermittent power sources A reliable integration of intermittent power sources in na islanded system requires: –Advanced management and control systems to minimize operation costs and assure security of operation; –Exploitation of storage facilities, involving specific management and control strategies. A reliable integration of intermittent power sources in na islanded system requires: –Advanced management and control systems to minimize operation costs and assure security of operation; –Exploitation of storage facilities, involving specific management and control strategies.

21. © 2006 21 Conclusions Extend and adapt the concepts of distributed generation and microgeneration pursued lately in developed countries to the existing reality of developing countries Increase renewable power sources presence –Reliability improvements; –Reduce economic costs –Increases quality of life and economic development in local populations –Avoids CO2 emissions Extend and adapt the concepts of distributed generation and microgeneration pursued lately in developed countries to the existing reality of developing countries Increase renewable power sources presence –Reliability improvements; –Reduce economic costs –Increases quality of life and economic development in local populations –Avoids CO2 emissions