Mohamed Zakaria Kamh

Unbalanced Model and Power-Flow Analysis of Microgrids and Active Distribution Systems

This paper presents a three-phase power-flow algorithm, in the sequence-component frame, for the microgrid (μgrid) and active distribution system (ADS) applications. The developed algorithm accommodates single-phase laterals, unbalanced loads and lines, and three/four-wire distribution lines. This paper also presents steady-state sequence-component frame models of distributed energy resource (DER) units for the developed power-flow approach under balanced/unbalanced conditions. The DER models represent the synchronous-generator based and the electronically-coupled DER units. Both constant power (PQ) and regulated-voltage (PV) modes of operation of DER units are considered. The application of the developed power-flow method for two study systems is presented. The study results are validated based on comparison with the detailed solution of the system differential equations in time domain, using the PSCAD/EMTDC software tool.

A Unified Three-Phase Power-Flow Analysis Model For Electronically Coupled Distributed Energy Resources

This paper develops and presents a unified and generic three-phase, steady-state, fundamental-frequency, sequence-frame-based model of the voltage-sourced converter (VSC) for power-flow analysis of VSC-interfaced Distributed Energy Resource (DER) units. The model is unified since it represents: 1) three-wire and four-wire VSC configurations; 2) balanced and unbalanced power-flow scenarios; 3) various VSC control strategies and options; and 4) operating limits and constraints of the VSC and its host DER unit. Based on the developed model, a new power-flow algorithm in the sequence-component frame is also developed. To achieve numerical and computational efficiency, the interface-VSC operating limits are accommodated in the power-flow algorithm as an interleaved step. The accuracy of the developed model and the computational efficiency of the power-flow algorithm are demonstrated based on several case studies, and where applicable, the results are validated based on comparison with the exact time-domain solution, using the PSCAD/EMTDC software tool.

Economic Dispatch Using an Enhanced Hopfield Neural Network

Abstract This article introduces some modifications to the conventional Hopfield neural network (HNN) to enhance its performance. A comprehensive study of the effect of the HNN parameters on the solution quality of the economic dispatch problem (EDP), as a case study, has been made. By investigating the describing curves, the best values for the HNN parameters are tuned. To further improve the solution quality, an adaptive correction factor is proposed and introduced to the EDP solution obtained by the HNN. To investigate the effect of the modifications on the solution quality of the EDP, three case studies are selected and solved. Comparisons of results are then made with others to prove the validity and effectiveness of the proposed modifications.

Steady-State Model and Power-Flow Analysis of Single-Phase Electronically Coupled Distributed Energy Resources

This paper develops and presents the steady-state, fundamental-frequency model of the single-phase distributed energy resource (DER) unit which utilizes a single-phase voltage-sourced converter (VSC) as the interface medium. The model represents: 1) different operating and control modes and 2) the operational constraints and limits of the VSC and the host grid. The model is included in a sequential power-flow analysis method using: 1) a backward-forward sweep algorithm for single-phase laterals and 2) a sequence-components frame solver for three-phase networks. The interface-VSC operating limits are accommodated in the power-flow algorithm as an interleaved step to increase computational efficiency of the power-flow analysis tool. Case studies are conducted to evaluate and verify 1) the accuracy of the proposed model and 2) the computational efficiency of the power-flow algorithm.

Three-Phase Steady-State Model of Type-3 Wind Generation Unit—Part I: Mathematical Models

This paper develops a comprehensive mathematical steady-state fundamental-frequency model of the Type-3 wind driven unit, i.e., a doubly fed asynchronous generator (DFAG) and its associated converter system, for three-phase power-flow analysis. First, a novel steady-state, sequence frame-based model of the generic Type-3 unit, to represent 1) the control capabilities and 2) the operating limits of the rotor-side and the grid-side converters under balanced and unbalanced conditions, is developed. Then, new strategies to determine the reference set-points of the controllers for compliance with the operating limits, are also presented. The model, including the proposed strategies/algorithms, is incorporated in a three-phase, sequence frame-based, power-flow algorithm. Applications and validation of the developed model and the set-points update strategies, and evaluation of the computational efficiency of the power-flow algorithm will be presented in Part II of this paper.

Dynamic Economic Dispatch Using a Hybrid Hopfield Neural Network Quadratic Programming Based Technique

Abstract This article introduces a solution for the dynamic economic dispatch problem using a hybrid technique of the Hopfield neural network and quadratic programming. This hybrid algorithm is based on using the enhanced Hopfield neural network to solve the static part of the problem and the quadratic programming algorithm for solving the dynamic part of the dynamic economic dispatch. This technique guarantees the global optimality of the solution due to its look-ahead capability. The proposed technique is applied to and tested on an example from the literature, and the solution is then compared with that obtained by some other techniques to prove the validity and effectiveness of the proposed algorithm.

A hybrid Hopfield neural network-quadratic programming approach for dynamic economic dispatch problem

This paper introduces a solution of the dynamic economic dispatch (DED) problem using a hybrid approach of Hopfield neural network (HNN) and quadratic programming (QP). The hybrid algorithm is based on using enhanced HNN; to solve the static part of the problem; and the QP algorithm for solving the dynamic part of the DED. This technique guarantees the global optimality of the solution due to its look-ahead capability. The new algorithm is applied and tested to an example from the literature and the solution is then compared with that obtained by some other techniques to prove the superiority and effectiveness of the proposed algorithm.

Three-Phase Steady-State Model of Type-3 Wind Generation Unit—Part II: Model Validation and Applications

This paper presents the implementation and validation of the sequence-frame model of the Type-3 wind generation unit and the sequential sequence-frame power-flow solver (sequential-SFPS) algorithm, developed in the Part I of this paper. A set of case studies are reported to (1) validate the numerical accuracy of the developed model and the power-flow algorithm, (2) quantify the impact of the Type-3 control strategy on the steady-state three-phase power-flow solution, and (3) demonstrate the computational efficiency of the sequential-SFPS. Three test systems of different topologies, sizes, and parameters are examined. Where applicable, the results are validated based on comparison with the exact time-domain solution, using the PSCAD/EMTDC software tool.

A unified three-phase power-flow analysis model for electronically-coupled distributed energy resources

This paper develops and presents a unified and generic three-phase, steady-state, \hl{fundamental-frequency, } sequence-frame-based model of the voltage-sourced converter (VSC) for power-flow analysis of VSC-interfaced Distributed Energy Resource (DER) units. The model is unified since it represents (i) three-wire and four-wire VSC configurations, (ii) balanced and unbalanced power-flow scenarios, (iii) various VSC control strategies and options, and (iv) operating limits and constraints of the VSC and its host DER unit. Based on the developed model, a new power-flow algorithm in the sequence-component frame is also developed. To achieve numerical and computational efficiency, the interface-VSC operating limits are accommodated in the power-flow algorithm as an interleaved step. The accuracy of the developed model and the computational efficiency of the power-flow algorithm are demonstrated based on several case studies, and where applicable the results are validated based on comparison with the exact time-domain solution, using the PSCAD/EMTDC software tool.

Modified augmented hopfield neural network for optimal thermal unit commitment

This paper develops a novel solution methodology of the Thermal Unit Commitment Problem (TUCP) using modified Augmented Hopfield Network (AHN) with enhanced performance. The modifications are mandatory to eliminate the error that conventional AHN structure is reported to suffer from. This error originates from the mapping process, the corner stone in using AHN as an optimization tool. A new solution algorithm is developed by combining the AHN with the proposed modifications. In order to verify the effectiveness of the new algorithm, it is applied and tested to some examples reported in literature and the solution is then compared with that obtained by counterpart Artificial Intelligence (AI) techniques. Unlike other AI techniques, the solution obtained using the modified AHN is more optimal and satisfying all the operating constraints.