استفاده بهینه از IPP مبتنی بر انرژی های تجدیدپذیر برای مدیریت بار صنعتی Optimal utilization of renewable energy-based IPPs for industrial load management

Electricity supply industry finds it difficult to grow in tune with the increasing demands, leading to energy and peak demand shortages in many countries. In order to meet the higher demand during peak hours, the utility has to increase its generation capacity and to operate the costly peak generating units. Load management (LM) programs, which focus on reducing customer use or to supplement power by non-utility means of generation at the time of high utility system loads, have emerged as an effective tool to handle the peak demand deficit faced by the utilities. Load management in industrial sector assumes importance, as the industrial sector consumes about 41% of the total electrical energy generated on a worldwide basis [1]. Moreover, time of use (TOU) tariffs implemented by the utilities with the objective of flattening the load curve, causes additional financial burden by way of penal rate for consumption during peak hours. Electricity derived from any renewable energy source (RES) is considered ‘‘green’’ because of the negligible impact on greenhouse gas emissions [2]. Earlier the interest in green power was driven by the goal of replacing fossil fuels to minimise the dependence on oil. Now the perspective is wider with a broader goal of minimizing the emission of global warming gases resulting from burning of fossil fuels. RES offer a viable option to meet the challenge of achieving higher growth while conserving the natural resources base, which has considerably deteriorated due to rapid growth in population, urbanization and fossil fuel consumption. During the last two decades, electricity generation from renewable energy sources (RES) has been steadily increasing and the contribution from RES in the total electricity generation is about 2.2% at present on a worldwide basis [1]. In many countries, the growth rate of this sector is very much above the world average. For example in India, the installed capacity of RES has grown to 11,125.41 MW at present and it constitute about 8% of the total [3]. Small hydro power (SHP) plants are small-scale decentralized power generating systems, which can generate electric power at low cost. SHP as a renewable energy source is proven, clean and environmentally benign. With considerable amount of potential remaining untapped, SHPs can offer a major contribution to electrical power generation. Wind is the next most popular source of green electricity around the world. The cost of wind-generated electricity has declined about 90% over the last 20 years [2]. At present, large wind farms at excellent wind sites are generating electricity at a cost which is competitive with that of electricity from conventional power plants. With an estimated 14,000 MW of annual worldwide installed generation capacity, biomass power is the third largest source of renewable electricity, behind hydro and wind. It is expected that the continued need for onsite industrial power, waste reduction, stricter environmental regulations, and rising consumer demand for renewable energy will provide enough motivation for the growth of power generation from biomass. Among the various RES options, SHP, biomass and wind power alone are considered for LM application, as these systems have matured technologies, which can generate electricity at a cost comparable with that of fossil fuel power. The performance and impact of a decentralized biomass gasifier-based power generation system in an un-electrified village has been discussed [4]. Attempts have been made to estimate the sustainable biomass production potential in various countries [5,6] and the cost of biogas based electricity production [7]. Potential areas in India, where provision of electricity through renewable energy-based decentralized generation options can be financially more attractive as compared to extending the grid, are identified [8]. Hybrid energy systems, incorporating combination of several renewable energy sources, for electrification of remote rural areas have been developed [9]. Development of SHPs in Turkey and the sustainability it can bring in has been discussed [10]. Attempts were made to address some of the important issues of utility wind integration that can affect utility system planning and operations [11]. Voltage source converter based HVDC transmission system technology has been used, to connect large doubly fed induction generator based wind farms over long distance, and the system performances during three-phase grid ac faults has been studied [12]. Wind power penetration in existing power systems have been studied to determine the right amount of wind power penetration, both from the reliability and economic point of view [13,14]. Most of these reported works are focused mainly on technological challenges and social benefits the RES bring in and do not generally address the problem of peak demand problem faced by the utilities. The possibility of utilizing the renewable energy resources to reduce the level of peak demand in Northern Cyprus has been examined [15]. The study relies on available renewable energy potential of the country, rather than a comprehensive mathematical model to decide the optimal operating strategies of RES plants. Suitability of power generation from renewable sources to fill the gap between peak load power demand and availability of power at the regional level in India has been evaluated [16]. The problem is formulated for the optimum allocation of the various renewable energy options to meet the peak demand. Linear programming (LP) methodology is used as a tool for the solution of selecting of the optimal mix of the renewable energy scheme. The model is developed, based on the estimated potential of various RES, without considering the techno-economic feasibility aspects and the non-linear characteristics. In the context of prevailing power shortage and peak demand deficit, application of RES based power generation is proposed, for load management in industrial sector. For reducing the peak demand and electricity cost of the industries, an optimal operating strategy has to be developed, which require the utilization of power from IPPs with least cost function. This necessitates a generalised model to determine the optimal operating strategy of the industries, to achieve the objective of minimizing the electricity cost and reduce peak demand under the specified electricity tariff, satisfying the system constraints. In this paper, a model for optimal utilization of renewable power for industrial load management is proposed. Non-linear fuel cost characteristics of the RES plants have been considered in the model.