Vol.6 No.3 2014
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Research paper : A proposal for setting electric power saving rate to avoid risk of electric power shortage occurrence (I. ARIZONO et al.)−138−Synthesiology - English edition Vol.6 No.3 (2013) rumored that the reason for the 15 % reduction in electricity consumption was not necessarily based on a scientific background. The possibility of intentional information control was also suspected. It may be said that this indicates insufficient information disclosure by the electric power companies including the Tokyo Electric Power Company and the Kansai Electric Power Company. In the present situation, it is necessary that each individual behaves so as not to create big societal confusion. However, this can only be done if some kind of convincing information is released that can induce people to reduce electricity consumptionAt the same time, as one conclusion to the decarburization of energy, an electric generating system based on renewable energy is considered. The purchase price of electricity based on renewable energy was decided under the Act on Special Measures Concerning Procurement of Renewable Electric Energy by Operators of Electric Utilities. However, since renewable energy is natural energy, the electricity supply based on renewable energy is affected by uncertain elements, e.g. weather and climatic conditions. In addition, the electricity demand is also influenced by weather and climatic conditions, which shows that the electricity demand also has much uncertainty. Moreover, because of the possibility of facility trouble and the need of maintenance check for the aging fatigue of existing facilities, the fluctuation in the electricity supply by the existing thermal power generating system should be considered.Therefore, when we consider the present situation in our country, both the expansion of electric generating facilities and the planning of electric power saving are required in order to evade electricity shortage outbreaks. In such cases, the uncertainties about the electricity supply and demand have to be put into consideration. Furthermore, considering the electricity demand-supply balance, the construction of a valid system to call for appropriate reductions in the electricity consumption is urgent.This paper addresses the evaluation of the electricity shortage outbreak probability of a case where there are stochastic fluctuations in the electricity demand and supply, keeping the current situation where there is no elbow room in electricity demand-supply balance in mind. It is supposed that the stochastic distributions of the electricity supply and demand are not exactly known, and that the limited information about the electricity supply and demand, such as the expectation and variance, are given. In this paper, the system for evaluating the electricity shortage outbreak probability is presented first. As one of the contributions of the electricity shortage outbreak probability evaluation system, a procedure for deciding the electric power saving rate for avoiding electricity shortage outbreaks is presented. The reasonableness of the decided request value of the electric power saving rate can be explained using the considered system. 2 Description of the problemThe greater part of generated electricity is produced in conventional facilities, e.g. thermal power generating systems and others. In addition to this, under the present situation, generated electricity based on renewable energy has become an urgent subject. The ratio of the electricity supply based on renewable energy among all of the electricity supply is around 3 % at present and the target in 2020 is 10 %.It is appropriate to consider that all of electricity produced by conventional electric generating systems and new generating systems based on natural energy fluctuates as mentioned above. The electricity supply based on renewable energy depends on the weather and/or climate conditions and may not necessarily bring a stable electricity supply. Accordingly, the electricity supply based on renewable energy can be understood as a random variable. Furthermore, since the temporary halts such as those caused by facility troubles or due to maintenance checks are supposed in the conventional generating systems like the thermal power generating system, electricity supply of conventional systems should also be understood as a random variable. The stochastic distributions of these random variables are not known exactly.Similarly, as mentioned above, by the voluntary reduction in electricity consumption of consumers, the current electricity consumption behaviors have certainly changed from conventional electricity consumption behaviors. Therefore, it is considered that the stochastic distribution of the electricity demand is also unknown.Under this situation, let us assume that each expectation and variance of the above random variables for the electricity demand and the electricity supply are available as limited information based on the forecast of the climate and weather of the next day. In this paper, the construction of the electricity shortage outbreak probability evaluation system is attempted based on the limited information about the electricity demand and the electricity supplies.Suppose the three random variables as follows: electricity supply in conventional electric generating systems: e0 (E[e0] = 0 and variance V[e0] = 02), electricity supply based on renewable energy: e1 (E[e1] = 1 and variance V[e1] = 12), electricity demand: e2 (E[e2] = 2 and V[e2] = 22),where the distributions for e0, e1 and e2 are unknown. Furthermore, the independency among the random variables e0, e1 and e2 is assumed. In this paper, first priority is to construct a system for evaluating the electricity shortage outbreak probability based on the limited information

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