This paper addresses robust frequency control in an islanded ac microgrid (MG). In an islanded MG with renewable sources, load change, wind power fluctuation, and sun irradiation power disturbance as well as dynamical perturbation, such as damping coefficient and inertia constants, can significantly influence the system frequency, and hence the MG frequency control problem faces some new challenges. In response to these challenges, in this paper, ${H} _{ {\infty }}$ and $ {\mu }$ -synthesis robust control techniques are used to develop the secondary frequency control loop. In the proposed control scheme, some microsources (diesel engine generator, micro turbine, and fuel cell) are assumed to be responsible for balancing the load and power in the MG system. The synthesized ${H} _{ {\infty }}$ and $ {\mu }$ -controllers are examined on an MG test platform, and the controllers’ robustness and performance are evaluated in the presence of various disturbances and parametric uncertainties. The results are compared with an optimal control design. It is shown that the $ {\mu }$ -synthesis approach due to considering structured/parametric uncertainties provides better performance than the ${H} _{ {\infty }}$ control method.

Robust Frequency Control in an Islanded Microgrid: ${H} _{\infty }$ and $\mu $ -Synthesis Approaches

Global environmental concerns, increasing energy demands and developments in renewable energy technologies present a new possibility to implement renewable energy sources. Solar energy is the most prominent among renewable sources, as it is an inexhaustible resource and its exploitation has thus far been ecologically friendly. The potential amount of solar energy is considerably greater than current worldwide energy demands. Solar energy has been developing more rapidly than the other renewable energy sources for the last few decades. The best way to harvest the sun’s power is photovoltaic (PV) technology. This paper presents a study on solar energy in the form of a stand-alone and hybrid power generation system used to electrify off-grid locations. The stand-alone solar-PV system developed here is intended to be used to power a single house or a small community and it also functions as a mini-grid, generating power in places where adequate solar radiation is available throughout the year. However, many places throughout the world experience unsteady amounts of solar radiation and in those places, a hybrid solar-PV system is the most efficient solution for electrification. The main benefit of the hybrid system is that the weakness of one source is covered by the other source. This paper also presents some comparative case studies, project examples and demonstrations of stand-alone solar and hybrid solar systems implemented at various locations throughout the world over the last twelve years.

Comparative study of stand-alone and hybrid solar energy systems suitable for off-grid rural electrification: A review

This paper presents a study about an off-grid (stand-alone) photovoltaic (PV) system for electrification of a single residential household in the city of Faisalabad, Pakistan (31.42°N, 73.08°E, 184 m). The system has been designed keeping in view the required household load and energy available from the sun. The complete model for the sizing of complete PV system has been presented to determine the required PV power rating, battery storage capacity, size of charge controller and inverter to fulfill the required load. Using this model, the peak power and area of PV modules, capacity of battery backup, size of charge controller and inverter was calculated to be 1928 Wp and 12.85 m2, 9640.5 W h, 56.65 A and 1020 W, respectively. The economics evaluation using life cycle cost (LCC) analysis of the complete system has also been carried out. The LCC of the system was found to be PKR. 457,306 whereas the annualized life cycle cost (ALCC) was determined to be PKR. 31,963 yr−1, respectively. The unit electricity cost has also been calculated and was found to be PKR. 14.8 kW h−1. The results show that unit cost of electricity produced using off-grid PV system is lower than the unit cost charged in case of conventional electric supply to the residential areas. It is concluded that off-PV electricity is technically and economically viable technology for the electrification of residential applications.

Design and economics analysis of an off-grid PV system for household electrification

The energy demand across the globe has increased in many folds due to technological advancement, rapid growth in industries and increase in household energy demand. This led the engineers and planners to think and find the means to harvest the alternative energy sources other than the fossil fuel. Solar, wind, biomass, mini hydro are some of the resources used worldwide to generate energy as per the availability of resources. This paper presents a comparative performances of various stand alone solar photovoltaic(PV), grid connected PV and hybrid renewable energy system (HRES) studied across the globe. The standalone PV system is used to supply electricity to a small habitats/hamlets or to a single household. Hybrid energy system consists of two or more energy sources for generation of power for rural electrification in off grid locations and in grid connected PV systems, excess electricity produced is injected to the grid thereby generating additional income. The research works carried out by various researchers around the globe on renewable energy sources particularly for rural electrification is discussed in this paper. Besides this the utilisation of renewable electricity for Plug-in-Electric Vehicles (PEV) studied across the globe were also discussed.

Performance evaluation of stand alone, grid connected and hybrid renewable energy systems for rural application: A comparative review

Performance analysis of a 11.2 kWp roof top grid-connected PV system in Eastern India

http://wgbis.ces.iisc.ernet.in/biodiversity/sahyadri_enews/newsletter/issue45/bibliography/Rural%20electrification%20in%20India%20and%20feasibility%20of%20Photovoltaic%20Solar%20Home%20Systems.pdf

R.Y. Udaykumar

Papers

Rural electrification in India and feasibility of Photovoltaic Solar Home Systems