Walid A. Omran

A decentralized coordination strategy for voltage regulation of active distribution networks

This paper presents a fully decentralized coordination strategy based on Multi-Agent System (MAS) for voltage regulation in active distribution networks (ADNs). The strategy is based on coordinating the operation of Distributed Generators (DGs) and On-Load Tap Changer (OLTC) to maintain the bus voltages within acceptable limits. The strategy attempts to maximize the use of the renewable based DGs while minimizing the operation of the OLTC. Several case studies are presented to show the effectiveness and robustness of the proposed strategy.

A Decentralized Technique for Autonomous Service Restoration in Active Radial Distribution Networks

This paper proposes a fully decentralized multi-agent system (MAS) based technique for service restoration of radial distribution networks. The technique utilizes expert system rules and considers the customers’ priority and the presence of distributed generators (DGs). It also considers the operational constraints in both healthy and restored sections of the feeder. The technique relies on one type of agents only, hence, simplifying its implementation. Moreover, it allows for assigning a back-up decision making agent to improve the reliability of the restoration process. The effectiveness of the technique is validated through several case studies simulated on an 11 kV distribution feeder. The agents are implemented in Java Agent Developing Framework (JADE) environment for communications and decisions making. Power flow calculations are performed in MATLAB environment to validate the correctness of the agents’ decisions.

Mean variance mapping optimization for solving economic load dispatch problem

The mean variance mapping optimization technique (MVMO) is employed in this paper to solve the economic dispatch problem (ED) in power systems. The effectiveness of the proposed technique has been verified on three different case studies to solve the ED problem of thermal power units taking into account the transmission losses and other constraints which include generation limits, ramp rate limits, prohibited operating zones and valve-point loading. The obtained results have demonstrated that MVMO is a promising approach for solving the optimization problems in practical power systems. Moreover, the number of control parameters in MVMO to be tuned is less than that in most of other metaheuristic technique which makes it simpler for solving non-convex optimization problems. Solution quality, convergence speed and robustness of MVMO technique has been compared with those of formerly proposed techniques.

Power management strategy to enhance the operation of active distribution networks

This paper focuses on the power management of renewable energy based distributed generators (RDGs) installed in medium voltage distribution networks (DNs). The goal of the study is to propose a strategy that improves the operation of the distribution network by utilizing the available resources efficiently. This is achieved by continuously managing the output power from the RDGs to meet the required demand. To achieve this task, the proposed strategy is divided into two stages; short-term planning stage and distribution network operation stage. In the short term planning stage, optimal power flow (OPF) is used to determine the output of the RDGs using forecasted data. The aim of the OPF is to minimize the power loss of the distribution network. The second stage aims to manage the actual output power of the RDGs using a multi-agent system (MAS). This stage is responsible for controlling any power imbalance that occurs between the generation and demand in each zone until the OPF is executed in the next time step. The OPF is performed using Particle Swarm Optimization (PSO) implemented in MATLAB, while the MAS is implemented in the JADE environment.

A probabilistic approach for the optimal placement of PMUs with limited number of channels

This paper presents a two-stage method for the placement of Phasor Measurement Units (PMUs) to achieve a fully observable power system while considering the PMUs channel limitation. The first stage uses the Binary Integer Linear Programming (BILP) to find the initial optimum locations of PMUs which ensure full system observability under normal conditions. The second stage uses state enumeration based on probabilistic failure of different components to ensure full system observability under single and double outages. The proposed method is validated using the IEEE 14-Bus system, IEEE 30-Bus system and IEEE 57-Bus system. The simulation results show that the method is efficient in providing detailed information about the observability of the power system under different operating conditions.

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.

Reliability assessment of grid connected photovoltaic generation systems

This paper investigates the reliability of different topologies of grid connected photovoltaic (PV) systems. The topologies considered in this study are centralized topology, string topology and multi-string topology. The reliability of each topology is evaluated by using suitable reliability indices that are based on calculating the probability of different operating states. These states are evaluated using the state enumeration method which is based on computing the failure rate of each component while considering the different environmental conditions. Simulations are performed in MATLAB environment on a 58.3 KW photovoltaic system to compare between the reliability of the three topologies.

Enhancing the Power System Observability with the Aid of Phasor Measurement Units

This paper presents an approach for optimally allocating the Phasor Measurement Units (PMUs) in a power system. The proposed approach is based on Binary Integer Programming (BIP) to minimize the total number of PMUs that can achieve full system observability. The full system observability is ensured both in normal operating conditions and in case ofN-1 contingencies such as the outage of a PMU or a transmission line. Moreover, the approach is utilized to allocate the PMUs in case of limited number of PMU channels. The problem formulation considers the Zero Injection Buses (ZIBs) and uses a set of rules that can improve the redundancy of the PMUs by choosing better locations without increasing their number. The proposed approach is applied on the IEEE standard systems 14, 30 and 57 test systems. The simulations results are compared with other approaches used in the literature to validate the performance of the proposed approach.