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The Optimal Distributed Generation Placement problem (ODGP) towards energy loss minimization depends basically on the network's layout and its load composition. Under load variations, different load compositions result, for each one of them, is highly possible to come up with a different optimal solution regarding the optimal siting and sizing of DG units. This paper examines the impact of these variations in order to verify how optimal solution should adapt to any load composition. A Local Particle Swarm Optimization Variant algorithm is proposed as the solution algorithm and numerous load composition snapshots for the IEEE-33 bus system are examined. Moreover, a methodology is proposed in order to highlight the critical nodes that prove to have an essential role to the solution. Finally, the possibility for the determination of a fixed solution with fixed installation nodes and constant power output that could yield near optimal energy loss reduction is examined.

a b s t r a c t A simple and novel methodology for the configuration of robust and distinct load signatures is presented in this paper. A technique based on a spectral analysis of the current waveform of each load is proposed, leading to load signatures consisting of three distinct spectral coefficients. Data required for each load signature come from only one period of the current waveform, under a sampling frequency at the order of kHz. A simple identification algorithm has also been developed in order to estimate the signatures adequacy. Each appliance has been measured and classified as an individual load, using a simple identification procedure. Data obtained from two different measurement sets show that the proposed technique provides unique data formations for each appliance tested by developing an efficient recognition procedure with high levels of identification rate. Due to the simplicity of both the database configuration and the identification procedure, the proposed methodology could be considered appropriate for online monitoring and real time smart grid applications. © 2014 Elsevier B.V. All rights reserved.

Photovoltaic (PV) power systems are becoming one of the most developing investment areas in the field of Renewable Energy Sources (RES). A statement of the status quo of PV power systems in Greece, and their contribution towards the improvement of power system reliability, is the scope of the present paper. Siting and installation of PV power systems is performed according to a recent Greek law, along with environmental and geographical constraints. Meteorological data are computed, formulated and imported to appropriate software in order to simulate the PV units and generate their power output. Data for unserved loads, resulting from load shedding during peak hours, are compared to the above estimated power production. Assuming that a proportion of the eventually unsupplied power could be provided by the accessed power generation of the PV units, the reliability of both transmission and distribution system is improved. The impact on the transmission system is shown by an improvement of LOLP and LOEP indices, whereas peak shaving for the Interconnected Greek Transmission System (IGTS) is also illustrated. For the distribution system the impact is quantified using the distribution system reliability indices SAIDI, SAIFI, and CAIDI. Finally, the resulting improvement is also expressed in financial terms.

Contemporary power distribution networks are no longer regarded as passive power system elements. On the contrary, novel control systems are being constantly developed over the last decade, aiming to achieve reliability improvement and operational optimization by means of power loss reduction, prompt fault detection and power restoration etc. A crucial aspect of the systems developed to achieve these goals will inevitably be their ability to integrate new functions without the need for further investment. In this paper, a multi agent system (MAS) initially developed for fault detection and power restoration is studied with respect to these issues. More specifically, a feasibility analysis is conducted regarding the implementation of the MAS on a segment of the underground 20 kV power distribution network of the city of Thessaloniki, Greece. The analysis focuses on the initial investment cost and the payback of the application, as well as on the additional benefits for the power distribution system operator due to the system reliability improvement. The ability of the MAS to incorporate loss reduction algorithms without further investment is also studied, and the respective benefits of the power distribution system operator are analyzed. Moreover, the feasibility analysis is generalized so as to be able to be applied to any power distribution automation implementation with similar attributes.