Feasibility Study of Operating An Autonomous Power System in Presence of Wind Turbines A Practical Experience in Manjil, Iran Hossein Sarparandeh, Moein Moeini-Aghtaie, Student Member, IEEE, Payman Dehghanian, Student Member, IEEE, Iraj Harsini, and Ahmad Haghani Iran Renewable Energy Organization Tehran, Iran Sarparandeh3@yahoo.com; M.Moeini@ieee.org; Payman.Dehghanian@ieee.org; Iraj_harsini@yahoo.com; Haghani@suna.org.ir Abstract—Commonly facing some irregular situations such as natural disasters and experiencing power interruptions as a consequence, the power grid in Manjil located in the north of Iran needs to be capable of power delivery to its local load points in an isolated manner. This paper aims to study the feasibility of this situation once local wind turbines are used as the power generation facilities. The imbalances of power supply and demand due to the high variation of wind power is overcome in this paper via employing and comparing two hydro-wind and diesel-wind power systems which are comprised of energy storage systems. This paper also investigates the balance feasibility of power supply and demand once the system is isolated from the whole power grid and offers an approach to identify the size and type of energy storages in this respect. The proposed method is proved to be an economic approach and results in an acceptable level of system reliability. Keywords-component; Isolated Microgrids; wind power; energy storage; power balance. I. INTRODUCTION Isolating a part of power system is reported as one of the most challenging problems in power system planning and operation once dealing with a catastrophic natural disaster [1]. This issue would be more challenging when wind power has to lend the power system operator a hand in providing the requested demands with sufficient power. The reason lies in the intermittency and variability of wind power once considered as a means of power generation [2]. Hence, major efforts have been so far concentrated on the isolated micro grids and their planning and operation in presence of renewable sources of energy. Isolating a part of power system can have significant influences in the reliability of the customers, as reported in [3]. Wind power penetration in power systems has seen an enormous research in the recent two decades to bring itself as a promising source of local power generation in small and medium-size isolated micro grids. Such power systems often use the diesel generators as a complementary to the employed wind farms [4]. As a result, these systems are usually called diesel-wind power systems. If the hydro-wind power generators are employed in addition to the conventional diesel generators, the result would be named a hybrid hydro-wind power generator. An autonomous power system with a high level of wind power is always facing an important question whether it can satisfy the balance of power generation and demand or not. The isolated hybrid power systems could guarantee the long-term power balance of supply and demand via the complementary units of wind power. In response to the fluctuations in the produced power of wind turbines, reference [4] proposes a scheme for the utilization of energy storage systems. This paper is founded based on the energy storage systems to implement a practical isolated micro grid in Manjil, Iran. This paper aims to offer a feasibility study to put into practice an autonomous power system in Manjil once facing some critical conditions. It also strives in finding the optimal sizes of hybrid wind-diesel and hydro-wind energy storage systems. The paper finally provides a thorough economical and technical comparison of these two types of energy storage systems and investigates their applicability and effectiveness in the system operation. In this respect, the obtained results and guidelines not only would be of great assistance when planning the Manjil power system as an isolated micro grid, but also gives conductive policy guides to the all power system decision makers around the world . The rest of the paper is organized as follows. Section II deals with the system introduction and tries in order to model its components. The type identification and sizing design of system components are conducted in Section III, wherein the proposed methodology in this paper is offered. The Manjil isolated power system is introduced in Section IV, the procedures are remarked, and finally the conclusion is outlined in Section V. II. SYSTEM INTRODUCTION AND THE MODELING PROCEDURE Numerical analysis is one of the most important tasks in the design, evaluation, and implementation process of isolated power systems. However, no numerical model can effectively and comprehensively cover all the operational