Fault Ride-through Capability Enhancement of Voltage Source Converter-High Voltage Direct Current Systems with Bridge Type Fault Current Limiters

Abstract

This paper proposes the use of bridge type fault current limiters (BFCLs) as a potential solution to reduce the impact of fault disturbance on voltage source converter-based high voltage DC (VSC-HVDC) systems. Since VSC-HVDC systems are vulnerable to faults, it is essential to enhance the fault ride-through (FRT) capability with auxiliary control devices like BFCLs. BFCL controllers have been developed to limit the fault current during the inception of system disturbances. Real and reactive power controllers for the VSC-HVDC have been developed based on current control mode. DC link voltage control has been achieved by a feedback mechanism such that net power exchange with DC link capacitor is zero. A grid-connected VSC-HVDC system and a wind farm integrated VSC-HVDC system along with the proposed BFCL and associated controllers have been implemented in a real time digital simulator (RTDS). Symmetrical three phase as well as different types of unsymmetrical faults have been applied in the systems in order to show the effectiveness of the proposed BFCL solution. DC link voltage fluctuation, machine speed and active power oscillation have been greatly suppressed with the proposed BFCL. Another significant feature of this work is that the performance of the proposed BFCL in VSC-HVDC systems is compared to that of series dynamic braking resistor (SDBR). Comparative results show that the proposed BFCL is superior over SDBR in limiting fault current as well as improving system fault ride through (FRT) capability.Moreover, VSC-HVDC offers a solution for many problems faced nowadays by power networks such as network congestion, grid reinforcement, multi-terminal DC (MTDC) operation and asynchronous operations of two different grids [10]. Different types of VSC topologies are proposed in the literature [11,12] including two level, three level and multilevel converters for HVDC transmission. Multilevel means more than two voltage levels can be achieved in one phase leg, which reduces the switching times of valve and makes the voltage wave form closer to a sinusoidal curve. Line to neutral voltage waveforms of both two-level and three-level converters with PWM are discussed and compared in [12].However, despite the numerous advantages, VSC-HVDC systems face difficulties in dealing with different grid faults [13]. Fault ride-through (FRT) capability enhancement is one of the main requirements for wind farm-integrated VSC-HVDC systems [14,15]. During system faults, bulk power interruptions must be avoided by keeping the HVDC system energized, otherwise, the system may face serious instability due to this bulk power interruption. Modular multilevel converter-based VSC-HVDC system topologies can provide enhanced fault ride-through capability [16]. In [17,18] FRT capability as well as transient stability improvement have been reported by applying various VSC control techniques. A power synchronization control technique has been proposed in [19] with coordination between wind turbines and HVDC controllers in order to achieve FRT ...

DC-Link Voltage Control of a Grid-Connected Solar Photovoltaic System for Fault Ride-Through Capability Enhancement

“…In addition to graphical representations to provide a clearer view, the LVRT has been evaluated using several performance indices, such as the PV active power deviation and DCL voltage deviations. A lower value of the indices indicates an enhanced system performance [32]. The performance indices are calculated using Equations (20)- (21):…”

Providing Fault Ride-Through Capability of Turbo-Expander in a Thermal Power Plant

“…As shown in Figure 7a-d, at the time of both the fault occurring (t = 0.5 s) and thee fault clearing (t = 1.5 s), negligible fluctuations come to pass in the compensated voltage, and there was no voltage sag and swell. In the DVR compensation scenarios (5)(6)(7)(8), all voltage sags according to Figure 7a-d, which correspond to 45%, 18%, 27%, and 9%, respectively, in the load side voltage were completely removed.…”

“…Therefore, a solution for the fault ride-through (FRT) capability of the TE should be provided. Available FRT strategies have been proposed for doubly fed induction generator (DFIG)-based wind turbines, and are divided into three categories of protection circuit configurations, reactive power injecting-device installation, and modified converter control structures [7,8]. Among these strategies, the reactive power injecting-devices have been widely applied to provide FRT capability (especially DVR and STATCOM) [9][10][11][12], and can support other power quality problems [13,14].…”

Non-Linear Control for Variable Resistive Bridge Type Fault Current Limiter in AC-DC Systems

“…The control block takes the deviation of reference DC link voltage (V DCref ) and measured DC link voltage (V DCmes ) of the HVDC link. As the HVDC system stability is mainly affected by the control action of the DC voltage control loop [45][46][47][48][49], the non-linear controller takes the amount of DC link voltage deviation as its input and provides variable duty (D) to emulate variable effective resistance during fault governed by the following non-linear equation:…”