DIGITAL SIMULATION AND ANALYSIS OF POWER SYSTEM

BY:- AMRIT PAUDEL(070MSP701)

Microgrid: Discussion of issues involved

MICROGRID: DISCUSSION OF ISSUES• Micro grids are small-scale, LV supply

networks designed to supply electrical and heat loads for a small community, such as a housing estate or a suburban locality, or an academic or public community such as a university or school, a commercial area, an industrial site, a trading estate or a municipal region

• suitable for supplying power to remote areas of a country where supply from the national grid system is either difficult to avail due to the topology or frequently disrupted due to severe climatic conditions or man-made disturbances

• Micro grids reduce environmental pollution and global warming through utilization of low-carbon technology

A TYPICAL MICROGRID CONFIGURATION

MODE OF OPERATION

Microgrid is operated in two modes:

• Grid-connected and • Standalone

INTERCONNECTION OF MICROGRIDS

• Microgrids are designed to generate power at distribution voltage level , they have restricted energy handling capability

• maximum capacity is normally restricted to approximately 10 MVA as per IEEE recommendations

• it is possible to supply a large load pocket from several Microgrids through a common distribution network, by splitting the load pocket into several controllable load units, with each unit being supplied by one Microgrid

TECHNICAL AND ECONOMIC ADVANTAGES OF MICROGRID• Environmental issues• Reduction in gaseous and particulate emissions due to

close control of the combustion process may ultimately help combat global warming

• Physical proximity of customers with micro sources may help to increase the awareness of customers towards judicious energy usage.

• Operation and investment issues • Improvement of reactive support of the whole system,

thus enhancing the voltage profile.• Reduction of T&D feeder congestion. • Reduction of T&D losses to about 3%. • Reduction/ postponement of investments in the

expansion of transmission and generation systems by proper asset management.

• Power quality • Decentralization of supply. • Better match of supply and demand.• Reduction of the impact of large-scale transmission

and generation outages.• Minimization of downtimes and enhancement of the

restoration process through black start operations of micro sources

• Cost saving • Market issues

CHALLENGES AND DISADVANTAGES OF MICROGRID DEVELOPMENT• High costs of distributed energy resources • Technical difficulties • Absence of standards • Administrative and legal barriers • Market monopoly

MANAGEMENT AND OPERATIONAL ISSUES OF A MICROGRID• For maintaining power quality, active and

reactive power balance must be maintained within the Microgrid on a short-term basis

• Microgrid operator should be able to choose the mode of operation within proper regulatory framework

• Temporary mismatch between generation and load should be alleviated through proper load forecasting and demand side management. The shifting of loads might help to flatten the demand curve and hence to reduce storage capacity.

• System security must be maintained through contingency analysis and emergency operations (like demand side management, load shedding, islanding or shutdown of any unit). Under contingency conditions, economic rescheduling of generation should be done to take care of system loading and load-end voltage/frequency.

• Economic operation should be ensured through generation scheduling, economic load dispatch and optimal power flow operations.

DYNAMIC INTERACTIONS OF MICROGRID WITH MAIN GRID• Small capacity of micro grid: stability of

main grid not affected• when Microgrids will become more

commonplace with higher penetration of DERs, the stability and security of the main grid will be influenced significantly

• the dynamic interactions between Microgrid and the main grid will be a key issue in the operation and management of both the grids

• Microgrids need to be designed properly to take care of their dynamic impacts on main grid such that overall stability and reliability of the whole system is significantly improved.