Metwally A. El-Sharkawy

A Classification Technique for Recloser-Fuse Coordination in Distribution Systems With Distributed Generation

In this paper, a novel approach is presented to study the impact of distributed-generation penetration on recloser-fuse coordination. The main core of this approach is based on an assessment process using a classification technique to classify the recloser-fuse coordination status at fault conditions to either coordination holds or coordination lost. Accordingly, the distribution system operator can take the proper decision. Then, two complementary actions are recommended in the proposed approach as a solution to decrease the number of cases where coordination is lost. The first one is to search for the best DG locations, where such locations are characterized by the minimum number of cases classified as coordination lost. The second one is based on changing the recloser setting in such a way to minimize the cases where coordination is lost. This new approach has been implemented on the IEEE 37-node test feeder using MATLAB-based developed software and the obtained results are presented and discussed.

Optimal Location of Thyristor-controlled Series Compensators in Power Systems for Increasing Loadability by Genetic Algorithm

Abstract This article presents an approach to find the optimal location of thyristor-controlled series compensators in a power system to improve the loadability of its lines and minimize its total loss. Also the proposed approach aims to find the optimal number of devices and their optimal compensation levels by using a genetic algorithm taking into consideration the thermal and voltage limits. Examination of the proposed approach is carried out on a modified IEEE 30-bus system.

VOLTAGE STABILITY ASSESSMENT OF MULTI-MACHINE POWER SYSTEMS USING ENERGY FUNCTION AND NEURAL NETWOKS TECHNIQUES

Voltage stability problems have been one of the major concerns for electric utilities as a result of heavy loading of power system. Steady state voltage stability analysis is effectively used to determine a stability margin that shows how close the current operating point of a power system to the voltage collapse point. This article presents a generalized energy function for voltage stability assessment of multi-machine power systems. The formulated energy function provides an excellent indicator of the system vulnerability to voltage collapse. It is, also, used to rank the system buses according to their contributions to voltage collapse. The proposed technique is applied to a test system and Ontario-Hydro real power system. Also, an investigation on the application of artificial neural networks (ANN) in voltage stability assessment has been developed. A multi-layer feed-forward ANN with error back-propagation learning algorithm is proposed for calculation of voltage stability margins (VSM). Extensive testing of the proposed ANN-based approach indicates its validity for determination of power system voltage collapse.

Optimal location of series FACTS to improve the performance of power system with wind penetration

Wind generation connection to power system affects steady state and transient stability. Furthermore, this effect increases with the increase of wind penetration in generation capacity. In this paper, optimal location of series FACTS devices is carried out to solve the steady state problems of wind penetration. Two case studies are carried out on the modified IEEE39 bus system, one with wind reduction to 20% and the second with wind penetration increase by 50% in the two cases system suffers from outage of one generator with load in one of system buses decreased by 15%. The system suffers from minimum voltage reduction, total loss increase and violation of power and power angle limits. This paper found that series FACTS devices in certain range are able to solve these problems associated with wind penetration in power systems.

Optimal Location of Thyristor-Controlled Series Compensation and Static VAR Compensator to Enhance Steady-state Performance of Power System with Wind Penetration

Abstract Wind generation connection to power system affects steady-state and transient stability. Furthermore, this effect increases with the increase of wind penetration in generation capacity. In this article, optimal location of flexible AC transmission system devices is carried out to solve the steady-state problems of wind penetration using a genetic algorithm. Case study is carried out on modified IEEE 39-bus system with wind penetration increases by 50%; the system suffers from outage of one generator with load decrease in one of system buses by 15%. The system suffers from minimum voltage reduction, total loss increase, and violation of power and power angle limits. Series and shunt flexible AC transmission system devices are used in this article. Results showed that series flexible AC transmission system devices in certain range are able to solve these problems associated with wind penetration in power systems with acceptable cost saving.

Recloser-Fuse Coordination Assessment by Classification Technique for Distribution Systems with Distributed Generation

Abstract In this article, a novel approach is presented to study the impact of distributed generation on recloser–fuse coordination. This approach is based on the assessment of the recloser–fuse coordination due to the penetration of distributed generation with specified location and capacity for a given fault location. This assessment process acts as a classifier based on finding the operating sequence of all reclosers and fuses in the path from the faulted node to the substation. This sequence is compared with a pre-required sequence obtained from the protection coordination philosophy and then provides the distribution system operator with a result indicating whether the recloser–fuse coordination still holds or is lost. Consequently the operator can make the proper decision according to this classification process. One of the proper decisions that can be taken into account in the case of recloser–fuse miscoordination is to adapt the recloser setting such that the coordination can be re-attained. This new approach has been implemented on the IEEE 37-node test feeder using MATLAB-based developed software (The MathWorks, Natick, Massachusetts, USA), and the obtained results are presented and discussed.

Transient Stability Assessment Using an Adaptive Fuzzy Classification Technique

The work presented in this article describes a scheme for applying the adaptive fuzzy classification technique on the power systems transient stability assessment (TSA) problem. In this technique, a fuzzy rule-based classification system was constructed. The proposed scheme was tested using a standard test power system. The results of the proposed approach were compared with the results obtained using the normal fuzzy technique. The comparison demonstrates the advantages obtained when using adaptive fuzzy technique over the normal fuzzy technique.

Power management in islanded microgrids using multi-agent systems

This paper presents a power management strategy for islanded microgrids. The proposed strategy utilizes the MultiAgent System (MAS) to perform the required tasks. The strategy is divided into two stages. The first stage is an operational planning stage which aims to optimize the operation of the microgrid in the islanded mode. This is achieved by performing Optimal Power Flow (OPF) periodically in the grid connected mode using a central agent. Once the islanded mode is detected, the results of the OPF are used to balance the operation of the microgrid. Several distributed agents along with the central agent aim to further fine tune the set points obtained from the OPF based on the actual operating conditions of the microgrid. To demonstrate the effectiveness of the proposed strategy, four scenarios are simulated and presented.

Effect of distributed generation modelling on performance of distribution systems

Due to the continuous increase of distributed generation (DG) penetration into distribution systems, load flow analysis always needs improvement to be more flexible, fast and computationally efficient especially when integrating DG with existing distribution systems. The work in this paper is divided into two parts; in the first part a new algorithm is developed to solve the power flow problem for radial distribution systems with DG modelled as PV bus. This algorithm can be applied for all distribution systems with any number of buses and laterals. In the second part, the developed load flow programme is employed to study the effect of changing the DG location on electric losses and voltage profile. The best location for DG can be determined accordingly to achieve minimum losses with best voltage profile. Typical case studies are implemented and the results obtained are presented and discussed.