S.O. Faried

Power system reliability enhancement using a thyristor controlled series capacitor

This paper examines the impact of a thyristor controlled series capacitor (TCSC) on power system reliability. In this application, the TCSC is employed to adjust the natural power sharing of two different parallel transmission lines and, therefore, enable the maximum transmission capacity to be utilized. In this context, a reliability model of a multi-module TCSC has been developed and incorporated in the transmission system. The results of the investigations show a significant improvement system reliability when utilizing the improvement is measured using the two indices of loss of load expectation (LOLE) and loss of energy expectation (LOEE).

Utilizing DFIG-Based Wind Farms for Damping Subsynchronous Resonance in Nearby Turbine-Generators

The paper presents the potential use of supplemental control of doubly-fed induction generator (DFIG)-based wind farms for damping subsynchronous resonance (SSR) oscillations in nearby turbine-generators connected to series capacitive compensated transmission systems. SSR mitigation is achieved by introducing a supplemental signal into the control loops of the DFIG voltage-sourced converter-based back-to-back. The validity and effectiveness of the proposed supplemental control are demonstrated on a modified version of the IEEE second benchmark model for computer simulation of subsynchronous resonance by means of time domain simulation analysis using the EMTP-RV program.

Damping power system oscillations using a fuzzy logic based unified power flow controller

This paper presents a new control method based on fuzzy logic technique to control a unified power flow controller (UPFC) installed in a single-machine infinite-bus power system. The objective of the fuzzy logic based UPFC controller is to damp power system oscillations. Phillips-Herffron model of a single-machine power system equipped with a UPFC is used to model the system. The fuzzy logic based UPFC controller is designed by selecting appropriate controller parameters based on the knowledge of the power system performance. Simple fuzzy logic controller using mamdani-type inference system is used. The effectiveness of the new controller is demonstrated through time-domain simulation studies. The results of these studies show that the designed controller has an excellent capability in damping power system oscillations

Reliability Evaluation of an HVDC Transmission System Tapped by a VSC Station

Reliability evaluation of multiterminal HVDC systems has received very little attention in the past. This paper presents reliability modeling and analysis of an HVDC transmission system incorporating a voltage-sourced converter (VSC) tapping station. The use of VSC tapping stations enables the supply of power along the route to areas with comparatively little consumption. In this paper, a comprehensive detailed reliability model is developed and then converted to a manageable and computationally efficient model. Using this equivalent reliability model, various reliability indices are calculated at the load point of the system and the impacts of the VSC tapping station on these indices are illustrated. Sensitivity analyses are conducted to investigate the impacts of the load level and the location of the tapping station on the reliability indices. The conducted studies are numerically applied on a typical HVDC system and thorough discussions are presented.

Enhancement of Power System Dynamics Using a Phase Imbalanced Series Compensation Scheme

The paper presents a new series capacitive compensation concept, which enhances power system dynamics. The idea behind the concept is a series capacitive compensation which provides balanced compensation at the power frequency while it results in phase imbalance at other frequency of oscillations. The compensation scheme is a combination of a single-phase thyristor controlled series capacitor (TCSC) and fixed series capacitors in series in one phase of the compensated transmission line and fixed capacitors on the other two phases.

Stochastic evaluation of voltage sag and unbalance in transmission systems

Voltage sags, also known as dips, are important to industrial reliability. This paper presents a Monte Carlo based approach to evaluate the maximum voltage sag magnitudes as well as the voltage unbalance in transmission systems. In this context, investigations have been conducted on a system model taking into consideration the uncertainty in several factors associated with the practical operation of a power system. MATLAB is used in the simulation studies.

Coordinated Control of Wind Energy Conversion Systems for Mitigating Subsynchronous Interaction in DFIG-Based Wind Farms

The paper presents methods for mitigating subsynchronous interaction (SSI) between doubly fed induction generator (DFIG) based wind farms and series capacitor compensated transmission systems. SSI damping is achieved by introducing a supplemental control signal in the reactive power control loop of the grid side converter of DFIG and full-scale frequency converter wind turbines, as well as in the reactive power control loop of the HVDC onshore multimodule converter (MMC) of offshore wind farms. This paper also investigates the impact of the phase imbalance series capacitive compensation concept that was introduced in the 1990s as a subsynchronous resonance countermeasure on SSI damping. The validity and effectiveness of the proposed methods are demonstrated on a test benchmark through time domain simulation studies using the ElectroMagnetic Transient Program (EMTP-RV).

Damping Inter-Area Oscillations Using Phase Imbalanced Series Compensation Schemes

The recently proposed phase imbalanced series capacitive compensation concept has been shown to be effective in enhancing power system dynamics as it has the potential of damping power swing as well as subsynchronous resonance oscillations. In this paper, a comparative effectiveness of two “hybrid” series capacitive compensation schemes in damping inter-area oscillations is evaluated. A hybrid scheme is a series capacitive compensation scheme, where two phases are compensated by fixed series capacitor (C) and the third phase is compensated by either a TCSC or SSSC in series with a fixed capacitor (Cc). The effectiveness of both schemes in damping inter-area oscillations for various network conditions, namely different system faults and tie-line power flows is evaluated using the EMTP-RV time simulation program.

An SSSC-Based Hybrid Series Compensation Scheme Capable of Damping Subsynchronous Resonance

The recently proposed phase-imbalanced series capacitive compensation concept has been shown to be effective in enhancing power system dynamics since it has the potential to damp power swings as well as subsynchronous resonance oscillations. In this paper, the series capacitive compensation concept is investigated for damping subsynchronous resonance oscillations using a static synchronous series compensator (SSSC)-based hybrid series-capacitive compensation scheme. In this scheme, the series capacitive compensation in one phase is created by using a single-phase SSSC in series with a fixed capacitor , and the other two phases are compensated by the fixed series capacitors (C). The validity and effectiveness of the proposed scheme are evaluated on the IEEE first and second benchmark models for computer simulation of subsynchronous resonance by means of time-domain simulation analysis using the Electromagnetic Transients Program-RV program.

Effect of HVDC converter station faults on turbine-generator shaft torsional torques

This paper explores the impact of HVDC converter station faults on the torsional torques induced in turbine-generator shafts. In this context, investigations have been conducted on a large turbine-generator unit connected to an HVDC system. Faults considered are firethrough, misfire and a short-circuit across a nonconducting valve. The effect of the fault incidence time on the maximum turbine-generator torsional torques is also investigated. The results of these investigations are presented in the form of typical time responses as well as parametric studies.