Search

Distributed Generation (DG) is gaining in significance due to the keen public awareness of the environmental impacts of electric power generation and significant advances in several generation technologies which are much more environmentally friendly (wind power generation, micro-turbines, fuel cells, and photovoltaic) than conventional coal, oil and gas-fired plants. Accurate assessment of energy losses when DG is connected is gaining in significance due to the developments in the electricity market place, such as increasing competition, real time pricing and spot pricing. However, inappropriate modelling can give rise to misleading results. This paper presents an investigation into the effect of load models on the predicted energy losses in DG planning. Following a brief introduction the paper proposes a detailed voltage dependent load model, for DG planning use, which considers three categories of loads: residential, industrial and commercial. The paper proposes a methodology to study the effect of load models on the assessment of energy losses based on time series simulations to take into account both the variations of renewable generation and load demand. A comparative study of energy losses between the use of a traditional constant load model and the voltage dependent load model and at various load levels is carried out using a 38-node example power system. Simulations presented in the paper indicate that the load model to be adopted can significantly affect the results of DG planning.

This paper presents a methodology for modeling and analyzing the load demand in a distribution system due to electric vehicle (EV) battery charging. Following a brief introduction to the common types of EV batteries and their charging characteristics, an analytical solution for predicting the EV charging load is developed. The method is stochastically formulated so as to account for the stochastic nature of the start time of individual battery charging and the initial battery state-of-charge. A comparative study is carried out by simulating four EV charging scenarios, i.e., uncontrolled domestic charging, uncontrolled off-peak domestic charging, “smart” domestic charging and uncontrolled public charging-commuters capable of recharging at the workplace. The proposed four EVs charging scenarios take into account the expected future changes to the electricity tariffs in the electricity market place and appropriate regulation of EVs battery charging loads. A typical U.K. distribution system is adopted as an example. The time-series data of EV charging loads is taken from two commercially available EV batteries: lead-acid and lithium-ion. Results show that a 10% market penetration of EVs in the studied system would result in an increase in daily peak demand by up to 17.9%, while a 20% level of EV penetration would lead to a 35.8% increase in peak load, for the scenario of uncontrolled domestic charging-the “worst-case” scenario.

The paper presents a case study in Oman to reduce the CO2 emission by diesel-photovoltaic based distributed power system feeding to a house located in remote area. Model of a hybrid power system comprising of a photovoltaic module, along with a diesel generator and essential auxiliary devices is proposed. The actual average solar radiation and residential load data, collected from the meteorological department and local utility office are used in this case study. The simulation results carried out using HOMER software indicate that the proposed hybrid system is attractive to reduce CO2 emission by 38% when compared to the diesel system alone, and by 2.67 % compared to the main interconnected system. The study also includes operational and per unit energy cost estimates. It is seen that the diesel-photovoltaic hybrid system is attractive in terms of operational costs, which is lower by 29.44% compared to the diesel system; while per unit energy cost is 12.08% lower. It may be noted that the cost estimates arrived at for main interconnected system are better in terms of per unit energy cost, which is lower by 8.43 % compared to the proposed hybrid system, while it is not attractive in terms of CO2 emissions. The Kyoto Protocol provides various mechanisms like joint implementation, clean development mechanism and international emission trading that enable countries to acquire GHG reduction credits. The evaluation and deployment of carbon credit is a key component to mitigate the growth in concentration of GHG. Prabhakant and Tiwari (2) have carried out an analysis to determine the carbon credits earned using standalone solar PV system which is encouraging and cost effective than conventional power generation. The other viable option to curb the carbon emission is substantial use of renewable energy along with the conventional resources. The paper presents a case study to reduce the GHG by proposing a Diesel-Photovoltaic Hybrid System (D-PVHS) feeding to a house located in remote area. The reminder of this paper is organised as follows. Second section presents the historical data of CO2 emission and daily residential power demand. Section III estimates the emission factor and energy cost of Main Interconnected System (MIS) feeding to the residential sector. Section IV describes the potential of renewable energy in the Oman. The model development is described in Section V. The application of this case study is explained in section VI. Results and discussion are described in section VII while conclusions of the study are presented in section VIII.

This paper presents the cost reduction of electricity generation using a hybrid system on an Island network in the Sultanate of Oman. A case study has been carried out for Masirah Island having an installed capacity of about 9 MW of diesel generators. Load characteristics of the island are considered to determine the necessary demand to be met by the hybrid system. A wind turbine model is developed to determine the potential of mechanical power available for wind generators at Masirah Island based on its daily wind speed profile. The cost of wind and diesel power generation is determined by considering three factors viz. capital cost, running cost and maintenance cost. Ten 900-kW wind turbine units are considered for wind power generation. The case study shows that overall cost of electricity generation by the proposed hybrid system is considerably less compared to the cost of diesel generation alone. The paper also addresses the benefits of the wind-diesel hybrid system in terms of the reduction in carbon emission, and outlines other benefits of the proposed scheme relating to providing power to isolated communities as verified by Masirah Island.

The promotion of distributed generation (DG) is a direct consequence of an international drive for sustainable development and advances in technology. At present, the development of environmentally friendly (renewable energy sources) and high efficiency power generation (combined heat and power) has attracted significant attention all over the world. However, traditional supervision and management systems in the power industry prevent a full understanding of the benefits of DG, especially those impacting on the environment, by the policy maker and policy executor. This has therefore, hindered the realisation of the full environmental benefits of DG. In this paper, some indices are introduced to quantitatively analyse the value of the environmental benefits of DG in China. In addition, a new mathematical model for calculating the true generation cost of DG was established based on the environmental benefits indices. In this model, a penalty mechanism was introduced for the pollutant emissions of power generation and the environmental value of pollutant emissions was also considered. Simulation results show that the indices and the new model can correctly reflect the environmental benefits and their application should accelerate the development of DG in China.