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Stability of Remote Microgrids: Control of Power Converters
Published in Md. Rabiul Islam, Md. Rakibuzzaman Shah, Mohd Hasan Ali, Emerging Power Converters for Renewable Energy and Electric Vehicles, 2021
Mohd. Hasan Ali, Sagnika Ghosh
A TSC is a FACTS device used for reactive power compensating in electrical power systems. A TSC normally comprises three main items of equipment: The main capacitor bank, the thyristor valve and a current-limiting reactor, which is usually air-cored. The largest item of equipment in a TSC, the capacitor bank is constructed from rack-mounted outdoor capacitor units, each unit typically having a rating in the range 500–1000 kilovars (kVAR). The power capacitor is connected in series with an anti-parallel thyristor [24–25]. To protect the thyristors, a current limiting inductor (reactor) is used which limits the peak current and the rate of rise of current (di/dt) when the TSC turns on at an incorrect time. In TSC, thyristors are connected in anti-parallel pairs and these pairs are connected in series. The anti-parallel connection of the thyristor makes the flow of current in both directions unlike the commercially available thyristors that can conduct only in one direction.
Power Delivery Systems: Transmission and Distribution
Published in J. Lawrence, P.E. Vogt, Electricity Pricing, 2017
The converter station can also be operated in a reverse fashion to invert a DC input to an AC output with the same thyristor valve circuits used for rectification. With a DC input, the output of a thyristor valve is a square wave. With commutating circuit components, a simple thyristor bridge is made to produce an alternating square wave. The use of 6-pulse and 12-pulse designs yields a more trapezoidal-shaped alternating waveform that is the result of summing the square wave outputs of the various thyristor valves (which are fired in time sequence stages). This output consists of the fundamental frequency (e.g., 60 Hz) plus harmonics, the content of which depends on the number of valves utilized in the converter station. AC filters are used to absorb the harmonic currents. The resulting AC output current leads the voltage, and thus the converter requires compensating reactive power.
Protection of Reactors and FACTS Devices
Published in Ramesh Bansal, Power System Protection in Smart Grid Environment, 2019
K. A. Nzeba, J. J. Justo, Aishwarya Biju, Ramesh Bansal
A TSC is always connected in delta where each phase consists of a thyristor valve, a reactor and a capacitor bank. The thyristor valve is electrically located between the reactor and the capacitor bank. The capacitor bank is generally divided in two parallel halves constructed by the series/parallel combination of a number of capacitor units. As for TCRs or TSRs, TSCs are mainly protected using the differential protection relays. An overcurrent relay sensing the line currents in the TSC can be used as backup protection system. Unbalance protection function supervises the voltage across the capacitor by measuring unbalance current.
A design optimisation tool to minimise volume and failure rate of the modular multilevel converter and the thyristor-controlled rectifier
Published in Journal of Marine Engineering & Technology, 2023
Tanvir Ahmed Toshon, M. O. Faruque
For thyristor-controlled rectifiers, each thyristor valve contains a snubber circuit. The purpose of the circuit is to provide compensation for the voltage overshoots during the thyristor turn-off process. Typically snubber capacitors are employed in parallel with the thyristor switch and snubber resistors are in series with the switch. ABB provides experimental study results for designing snubber circuits for their thyristors (Waldmeyer and Backlund 2008). The experimental results are available from the manufacturer and can be used to obtain parameters such as required capacitance and resistance for the circuit. Additionally, TCR is subjected to DC side harmonics that lead to performance degradation of the converter. Since the proposed algorithm designs a twelve-pulse converter, the major focus is 12th and 24th harmonics and a filter has been designed to suppress them. This filter is composed of a combination of capacitors and inductors, detailed modelling of which can be found in Arrillaga and Watson (2004).
Optimal Locations and Sizes of Shunt FACT Devices for Enhancing Power System Loadability Using Improved Moth Flame Optimization
Published in Electric Power Components and Systems, 2022
Mahrous Ahmed Taher, Salah Kamel, Francisco Jurado, Juan Yu
SVC can be considered as a variable reactance connected in shunt with the power system. SVC can absorb or inject reactive power from the system according to the current state for regulation of the voltage at the connection point with the network. Both of reactive power support and voltage regulation can be obtained by SVC leads to enhancement of the power system stability. The most commonly used types of SVC are; Fixed Capacitor (FC) with Thyristor Controlled Reactor (TCR) which called FCTCR and FC with thyristor reactor (TSR) which called FCTSR [41, 42]. FCTCR type is implemented in this article TCR is comprised of reactor with fixed inductance L and a thyristor valve working simultaneously in two directions via controlled firing angle within the range (90°: 180°) related to the voltage of SVC.
Comprehensive investigation on doubly fed induction generator-Wind farms at fault ride through capabilities: technical difficulties and improvisations
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Preeti Verma, Seethalekshmi K, Bharti Dwivedi
Various control topologies for the control circuit of DVR have also been existing in literatures. Conventional vector control and advanced control techniques like fuzzy-based control, control, nonlinear adaptive control, feedback linearizing control, etc., are used in DVR. Limitation of the controller can exhibit requirement of different approaches for the controller. A perturbed compensation-based adaptive controller is discussed in (Yan et al. 2018).This controller is used to estimate parametric uncertainties and disturbances. It gives better result in dynamic performance at time-varying wind power and grid disturbances. A robust controller scheme is essential for field implementation. A Thyristor Controlled Series Capacitor (TCSC) is also used in series compensation in DFIG-WT. A series capacitor and bidirectional thyristor valve is used in TCSC (Joshi and Mohan 2006).