In recent years, the inclusion of flexible AC transmission systems (FACTS)-based compensating devices such as a thyristor-controlled series capacitor (TCSC) and a unified power flow controller (UPFC) has been increased in high-voltage power transmission systems due to numerous technical and economical benefits. However, the operation of such FACTS devices introduces harmonics and non-linearity in power system and causes fast changes in line impedance. As a result, the most widely used fixed impedance setting based distance relaying scheme finds limitation in protecting such compensated lines. Significant research has been carried out in recent years to develop new algorithms and methods to address the problem. This paper presents a comprehensive review of recent developments in the protection of TCSC/UPFC compensated high-voltage transmission lines. The relative merits and demerits of each of the available methods are also presented for comparison. Prior to detail review, the impact of TCSC/UPFC on distance protection is evaluated by using data generated through EMTDC/ PSCAD on a 400 kV two-bus test power system. This study can be useful to both academic researchers and practicing engineers to gain insight on the protection of FACTS compensated transmission lines and for further development of newer algorithms. 2 FACTS compensated high-voltage transmission lines: protection challenges The basic configuration and the different operating modes of TCSC and UPFC controllers and their impacts on the distance protection are well documented in [10-16], respectively. However, for the sake of completeness, in this section, the impact of TCSC/UPFC compensated transmission lines on the performance of distance relay is evaluated by using data simulated through EMTDC/ PSCAD on a 400 kV test power system.
Summary
Modern digital distance relays are incorporated with power swing blocking functions to avoid false operation during power swing. At the same time, it is also crucial to detect a fault correctly and quickly if occurs during power swing for unblocking and allowing the relay to trip the line. Detection of faults in thyristor controlled series capacitor (TCSC) compensated transmission lines during power swing is very challenging due to the nonlinear functioning of the thyristor controlled reactor and the metal‐oxide varistor protecting the series capacitor. This paper proposes a fault detection technique for TCSC compensated transmission lines during power swing using the generalized Teager‐Kaiser energy operator on the instantaneous current signal. The performance evaluation on a wide variety of test data generated on the modified WSCC three‐machine nine‐bus system and the modified IEEE 39‐bus New England system through EMTDC/PSCAD justify the efficacy of the proposed method.
Series-compensated transmission lines (SCTLs) are increasingly preferred for transmitting bulk amounts of electricity generated from the present-day large-scale wind farm to the utility grid due to several technical and economic benefits. However, when a fault occurs in such a wind farm-integrated SCTL, the impedance across the metal oxide varistor (MOV)-protected series capacitor varies non-linearly. Also, the fault current contributed from the wind farm side is quite different compared to the grid side. Consequently, the widely used fixed impedance-based distance relaying schemes showed limitations when used for protecting such crucial TLs. In this paper, the impacts of series compensation and wind farm integration on distance relay are investigated, and this paper proposes an intelligent relaying scheme using only the current measurements. In the proposed scheme, the fault detection task is performed using the signs of the half-cycle magnitude differences of the line end positive-sequence currents, and the fault classification task is performed using only the local current measurements processed through the Fourier–Bessel series expansion (FBSE) bagging ensemble (BE) classifier. The non-stationary components present in the current signal at the initiation of a fault are captured by calculating FBSE coefficients, and the singular value decomposition is applied for dimensionality reduction of the feature set. Finally, the extracted features are used by the BE classifier for fault classification. The method is evaluated in MATLAB/Simulink® on numerous fault and non-fault data simulated in two-bus systems and also validated through the OPAL-RT (OP4510) manufactured real-time digital simulation platform. The obtained results (response time for fault detection and classification <10 ms), including the comparative assessment results (fault detection accuracy =100% and fault classification accuracy =99.37%), justify the effectiveness of the proposed relaying scheme in protecting the wind farm-integrated SCTLs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.