(1990). ENERGY FUNCTION ANALYSIS FOR POWER SYSTEM STABILITY. Electric Machines & Power Systems: Vol. 18, No. 2, pp. 209-210.

Energy function analysis for power system stability

This paper presents an over-review of various strategies applied to enhance the fault ride-through (FRT) capability of the doubly-fed induction generators (DFIGs) based wind turbines (WTs) during transient-state. As the DFIG based WT system is sensitive to any grid disturbance, various FRT techniques based on: (i) installation of additional protection circuits, (ii) installation of reactive power injecting-devices and (iii) specific control approaches/structures have been proposed in the literature. Usually, the protection circuits or control structures are applied to limit the generated rotor over-current and undesirable dc-link over-voltage during grid disturbance. Meanwhile, the reactive power injecting-devices surpass any deficiency of the reactive power so as to improve the transient performance of the DFIG based WT and automatically bound the rotor current and the dc-link voltage. Actually, many research findings demonstrate an efficient protection of the DFIG without jeopardizing its operating strategy during transient-state. Therefore, this study focuses on emphasizing the present status of the rotor over-current and dc-link over-voltage protection solutions e.g. the crowbar and its related protection circuits, the reactive power injecting-devices such as the static synchronous compensators (STATCOM) and dynamic voltage restorer (DVR). Moreover, some control (modified) approaches/structures for limiting the inrush rotor currents which are based on linear and nonlinear control strategies are presented. Following the description of the overall system characteristics under steady-state and transient-state in the d–q axis, various protection strategies are extensively discussed to reveal their role to improve the FRT. Then, typical case studies are presented to demonstrate and support the reviewed FRT schemes. In that case, using the simulation results from the MATLAB/Simulink software the effectiveness of each case study during network faults are analyzed and compared.

Doubly-fed induction generator based wind turbines: A comprehensive review of fault ride-through strategies

Sliding mode controller based on feedback linearization for damping of sub-synchronous control interaction in DFIG-based wind power plants

Performance improvement of photovoltaic power systems using an optimal control strategy based on whale optimization algorithm

Power systems are becoming more and more complex in nature due to the integration of several power electronic devices. Protection of such systems and augmentation of reliability as well as stability highly depend on limiting the fault currents. Several fault current limiters (FCLs) have been applied in power systems as they provide rapid and efficient fault current limitation. This paper presents a comprehensive literature review of the application of different types of FCLs in power systems. Applications of superconducting and non-superconducting FCLs are categorized as: (1) application in generation, transmission and distribution networks; (2) application in alternating current (AC)/direct current (DC) systems; (3) application in renewable energy resources integration; (4) application in distributed generation (DG); and (5) application for reliability, stability and fault ride through capability enhancement. Modeling, impact and control strategies of several FCLs in power systems are presented with practical implementation cases in different countries. Recommendations are provided to improve the performance of the FCLs in power systems with modification of its structures, optimal placement and proper control design. This review paper will be a good foundation for researchers working in power system stability issues and for industry to implement the ongoing research advancement in real systems.

https://www.mdpi.com/1996-1073/11/5/1025/pdf

Fault Current Limiters in Power Systems: A Comprehensive Review

This study provides review of grid-tied architectures used in photovoltaic power systems, classified by the granularity level at which maximum power point tracking (MPPT) is applied. Grid-tied PV power systems can be divided into two main groups, namely centralized MPPT (CMPPT) and distributed MPPT (DMPPT). The DMPPT systems are further classified according to the levels at which MPPT can be applied, i.e. string, module, submodule, and cell level. Typical topologies for each category are also introduced, explained and analyzed. The classification is intended to help readers understand the latest developments of grid-tied PV power systems and inform research directions.

/pdf/a-review-of-grid-tied-converter-topologies-used-in-4tc4czg3zd.pdf

A review of grid-tied converter topologies used in photovoltaic systems

This paper presents a new problem formulation for allocation of high-temperature superconducting fault current limiter (HTS-FCL) in power systems for security and stability enhancement. A dynamic current-dependent model for HTS-FCL is developed using PSCAD/ETMDC. The proposed formulation includes three functions related to security, voltage stability, and rotor angle stability which represent key features of deploying the HTS-FCL. The three functions were combined into a multi-objective function, and the problem is formulated as a mixed-integer nonlinear programming (MINLP) problem and optimal FCL locations are determined using particle swarm optimization. The optimal FCL locations for the New-England 39-bus system are determined, and the system transient performance is validated using MATLAB and PSCAD. The simulation results demonstrate the effectiveness of proposed approach for achieving optimal performance of HTS-FCL in power system in terms of security and system stability.

Optimal Allocation of HTS-FCL for Power System Security and Stability Enhancement

This paper proposed a novel fault ride-through (FRT) configuration and transient management scheme to enhance the FRT capability of doubly fed induction generator-based wind turbines. The new configuration of the grid-side converter introduces shunt and series compensation for normal operation and voltage dips, respectively. A braking resistor is added to smooth switching transients from shunt to series interfaces and dissipate excessive power from the grid-side converter. To attain a flexible control solution for balanced and unbalanced fault conditions, the proposed transient management scheme employs positive and negative sequence controllers. A small-signal linear model is developed and examined to analyze the system dynamics for the series compensation topology. Based on the mathematical model, the controller is tuned to balance both voltage regulation performance and transient stability margins with consideration of various operating conditions. The combination of shunt and series interfaces demonstrates a low component count, simple protection structure, and improved performance of FRT with effective compensation to the electric grid. A comprehensive simulation verified the capability of the new configuration and transient management scheme.

Novel Fault Ride-Through Configuration and Transient Management Scheme for Doubly Fed Induction Generator

This paper introduces the High Temperature Superconducting Fault Current Limiter (HTS-FCL) as a novel technology for mitigating the high fault currents and enhancing the security of Abu Dhabi Water and Electricity Authority (ADWEA) power system. The transient model of ADWEA power system is developed using the PSCAD/EMTDC simulation program. The transient model is validated in steady state and short circuit analysis with the PSS/E model of ADWEA power system. The proposed model is used to facilitate performing the electromagnetic transient studies for installing the HTS-FCL. The detailed time domain model of the HTS-FCL considering its major components, operation control algorithm, sequence of events and fault detection techniques are developed. The implementation of the HTS-FCLs in the 132-kV network of ADWEA power system is studied. Furthermore, the short-circuit currents levels to utilize all potential system equipments and remove the limitations on the available generation are analyzed. The reduction of the fault currents are evaluated at the buses of suspected high fault currents with installing the HTS-FCL to demonstrate its effectiveness for improving the system performance, reliability and security.

Novel Technique for Reducing the High Fault Currents and Enhancing the Security of ADWEA Power System

This paper addresses implementation issues associated with a novel damping control algorithms for STATCOM and SSSC (static synchronous series compensator) in a series compensated wind park for mitigating SSR (subsynchronous resonance) and damping power system oscillations. The IEEE first benchmark model on subsynchronous resonance is adopted with integrating aggregated self-excited induction generator based wind turbine to perform the studies. The potential occurrence and mitigation of the SSR caused by induction generator effects as well as torsional interactions, in a series compensated wind park are investigated. The auxiliary subsynchronous damping control loops for the STATCOM and SSSC based on a novel design procedure of nonlinear optimization are developed to meet the damping torque in the range of critical torsional frequencies. The performances of the controllers are tested in steady state operation and in response to system contingencies, taking into account the impact of short circuit ratios (SCRs). Simulation results are presented to demonstrate the capability of the controllers for mitigating the SSR, damping the power system oscillation and enhancing the transient stability margin in response to different SCRs.

M. S. El Moursi

Papers

A review of grid-tied converter topologies used in photovoltaic systems

Optimal Allocation of HTS-FCL for Power System Security and Stability Enhancement

Novel Fault Ride-Through Configuration and Transient Management Scheme for Doubly Fed Induction Generator

Novel Technique for Reducing the High Fault Currents and Enhancing the Security of ADWEA Power System

Novel control strategies for SSR mitigation and damping power system oscillations in a series compensated wind park