Ramadan El Shatshat

Decentralized Reactive Power Control for Advanced Distribution Automation Systems

In this paper a decentralized reactive power control scheme is proposed to optimally control the switched capacitor in the system in order to minimize system losses and maintain acceptable voltage profile. The proposed technique is based on placing a remote terminal unit (RTUs) at each DG and each at line capacitor. These RTUs being coordinated together through communication protocols form a multiagent system. Novel decentralized algorithm is proposed to estimate the voltage profile change as a result of injecting reactive power at the capacitor bus. Simulation results are presented to show the validity and the effectiveness of the proposed technique.

Artificial intelligent controller for current source converter-based modular active power filters

The control methodology of the active power-line filter is the key element for its successful performance in mitigating the line current harmonics. The control system processes the distorted line current signal and forces the converter to inject the proper compensating current. At the same time, it regulates the dc term, i.e., the dc current in the current source converter topology and the dc voltage in the voltage source converter topology. In this paper, a new intelligent control scheme for a modular single-phase active power filter based on the current source converter (CSC) topology is proposed. The intelligent controller utilizes two adaptive linear neurons (ADALINEs) to process the signals obtained from the power-line. The first ADALINE (the Current ADALINE) extracts the harmonic components of the distorted line current signal and the second ADALINE (the Voltage ADALINE) estimates the fundamental component of the line voltage signal. The outputs of the two ADALINEs are used to construct the modulating signals of a number of CSC modules, each dedicated to eliminate a specific harmonic. The proposed controller is also responsible for activating selected CSC filter module(s) to the electric grid. The automated activation of the corresponding filter module(s) is based on the decision-making rules in accordance with the current total harmonic distortion (THD/sub i/) and the harmonic factor (HF) levels set by the IEEE 519-1992 standard. A special 3-level PWM switching strategy is proposed for the filter modules which results in a 50% reduction in the overall switching losses compared with the 2-level method. The proposed controller adjusts the I/sub dc/ in each CSC module based on the present magnitude of the corresponding harmonic current which results in optimum dc-side current value and minimal converter losses. The high speed, accuracy, efficiency and flexibility offered by the proposed controller, combined with the fast response and low dc energy storage requirement of CSC topology, are the main advantages of the proposed active filter system. The analytical expectations are verified by digital simulation using EMTDC simulation package.

Optimal Control of Voltage Regulators for Multiple Feeders

In this paper, a new method is proposed for the control of voltage regulators that enables the regulation of multiple feeders having diversified loads using only one regulator. The selection of the tap position of the regulator is chosen based on the solution of an integer linear optimization problem. The main advantage of the method is that it has a closed-form solution for the optimal tap; a merit which is very valuable in real-time operation. The constraints for having the voltage of the regulating points within the range of permissible values were ensured. Also, the necessary condition for feasible solutions was examined. A simulation study was carried out to validate the proposed method.

Fault Detection, Isolation, and Service Restoration in Distribution Systems: State-of-the-Art and Future Trends

This paper surveys the conceptual aspects, as well as recent developments in fault detection, isolation, and service restoration (FDIR) following an outage in an electric distribution system. This paper starts with a discussion of the rationale for FDIR, and then investigates different areas of the FDIR problem. Recently reported approaches are compared and related to discussions on current practices. This paper then addresses some of the often-cited associated technical, environmental, and economic challenges of implementing self-healing for the distribution grid. The review concludes by pointing toward the need and directions for future research.

A review on energy management systems

In the context of implementing the smart grid, electric energy consumption, generation resources, energy storage, plug-in electric vehicles, should be managed and optimized in a way that saves energy, improves efficiency, enhance reliability and maintain security while meeting the increasing demand at minimum operating cost. As a consequence, energy management systems are receiving more attention from the researchers and utilities. Accordingly, the main concern of this work is to investigate different energy management systems whether owned by a customer or by the distribution system utility.

A Correlated Equilibrium Game-Theoretic Approach for Multiple Participants Electric Distribution Systems Operation

The implementation of smart grid permits different system participants (e.g., distributed generations and loads) to interact in a rational and independent behavior to improve the distribution system (DS) performance. Each participant is recognized as a selfish decision maker that selects actions that improve its own payoff leading to conflicts with others. Therefore, further investigations are required to improve the decision making process outcomes. In this paper, a decentralized cooperative algorithm is developed to manage the multiparticipants DS operation. The proposed algorithm has been developed based on a correlated equilibrium game-theoretic approach. The outcomes of the proposed algorithm were compared with the traditional existing “best response” (BR) game-theoretic approach, which was utilized in similar multiparticipants DSs that converge to Nash equilibrium. The proposed algorithm is tested with two different case studies that were selected by the DS operator. The proposed algorithm was verified using a modified IEEE 123-bus test feeder. The test results showed a superior system performance compared with traditional BR techniques.

Low voltage ride through capability enhancement of wind farms' generators: DVR versus STATCOM

This paper investigates the application of dynamic voltage restorer (DVR) versus static compensator (STATCOM) to enhance low voltage ride through (LVRT) capability of wind farms. The research done in the area of LVRT focused on a single machine compensation analysis; however, no such analysis was done for entire wind farms generators. Therefore, the main contribution of this paper is to study LVRT compensation through STATCOM and/or DVR in order to provide guidelines for the implementation of each solution within large wind farms. In this paper, squirrel cage induction generators (SCIGs) are studied using a simplified approach based on torque-speed characteristics of induction machines. The transient stability margin is proposed as indicator of LVRT capability. Analytical calculations are verified against simulation results using PSCAD/EMTDC package.

Optimal Distribution Systems Operation Using Smart Matching Scheme (SMS) for Smart Grid Applications

In the context of the implementation of smart grid, electric distribution systems operation should be managed and optimized in a way that saves energy, reduce CO2 emissions, allow for a seamless integration of renewable energy sources and improves the power quality, while still meeting increasing demands with minimum operating costs. Achieving these objectives requires efficient smart techniques that address both existing and future challenges with respect to the implementation of smart grid. This paper proposes a smart matching scheme (SMS) that will select the most efficient and economical distribution system (DS) controlled resources for a reliable and improved DS operation. The selected resources will then be optimally controlled to fulfill the operators needs while adhering to the operational constraints. Performance evaluation of different optimization problems with and without the use of the proposed SMS were conducted and applied on the IEEE 123 bus DS. The IEEE 123 test system is modified to include dispatchable and renewable distributed generations to match the performance of a typical electric distributions system.

A Smart IEC 61850 Merging Unit for Impending Fault Detection in Transformers

This paper proposes and experimentally validates the functionality of a smart IEC 61850 merging unit (MU) that supports self-healing and asset management functions of future power grids. The proposed MU can operate in a standalone or as an integrated element within a primary substation. The MU communicates with a supervisory control and data acquisition (SCADA) system over Ethernet and WiFi-5 GHz links. A dynamic wavelet-based windowing technique is implemented in the proposed MU to process signals and report limited situation awareness (SA) features. The SA features serve two purposes. First, they can be used by asset management functions to monitor and diagnose the equipment heath condition. Second, they can be employed by self-healing functions in order to detect and anticipate early stages of impending faults masked by high noise. The MU capability to acquire real-time sampling or estimated-time sampling is examined and the impact of wireless sensor network data transfer latency between the proposed MU and an SCADA system is also investigated. Extensive laboratory experiments show promising results for the proposed IEC 61850 MU as a smart tool that can monitor, control, protect, and also initiate corrective actions.

STATCOM modeling impact on wind turbines' Low Voltage Ride Through capability

Ideal Static Compensator (STATCOM) modeling may be deceiving for determining the protection device settings that will operate to fulfill Low Voltage Ride Through (LVRT) requirements of wind turbines. If these settings are not accurately calculated, premature tripping or machines instability may occur and hence LVRT will not be achieved in such cases. Therefore, a more realistic STATCOM model is introduced in this paper and compared to the ideal one. Squirrel Cage Induction Generator (SCIG) based wind turbines are studied using a simplified approach based on torque speed characteristics of induction machines. The transient stability margin is proposed as an indicator for LVRT capability. Theoretical expectations are verified by digital simulation using EMTDC simulation package.