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Grid-Connected Systems
Published in Mukund R. Patel, Omid Beik, Wind and Solar Power Systems, 2021
With recent advances in power electronics, the low-voltage ride-through (LVRT) capability that enables wind turbines to stay connected to the grid during system disturbances is among the technologies introduced in the market by many manufacturers. For example, the LVRT capability is now built into all of GE Wind’s new turbines, ranging from 1.5-MW units to the 12-MW units designed for offshore applications to meet more stringent transmission standards. On land, the 200-MW Taiban Mesa Wind Farm in New Mexico was the first project to install the ride-through capability.
Single AC/DC fault current limiter for both side of hybrid AC/DC microgrid
Published in International Journal of Electronics, 2023
A. Azizpour, M. Radmehr, M. Firouzi, G. B. Gharehpetian
In Kartijkolaie et al. (2021), a controllable dual-bridge SSFCL is proposed for interconnecting ACMGs to main grid. It consists of a shunt-controllable bridge rectifier and a series diode-bridge rectifier. The shunt rectifier acts as a variable DC voltage-source to compensate the DC reactor of power losses under normal operation condition and control the fault current under fault condition. In all these studies, the performance of different types of FCLs in ACMG or DCMGs has been investigated separately. Firouzi et al. (2020) proposed a multi-step bridge-type FCL for integration wind turbines to ACMG. It enhances the LVRT capability of wind turbines under different voltage sag conditions. In Abdolkarimzadeh et al. (2017), a bridge-type SSFCL has been proposed, which is connected between AC and DC MGs. It connects the ACMG to the DCMG to transfer fault current energy to the adjacent DCMG under fault condition in AC side. It provides an effective current limiting measure for AC side and energy storage for DC side. However, occurrence a short-circuit fault in the one of MGs affects the performance of the other MG.
LVRT Fulfilment of the DFIG-based WECS During Symmetrical Grid Voltage Dips
Published in IETE Journal of Research, 2022
Krishna S. Patel, Vijay H. Makwana
The rating of the converter is usually about 30% of the DFIG rated power. However, the rated voltage given at the rotor through the converter is typically around 690 V (low voltage) in order to reduce losses and the size and price of the converter [2]. The reduced power and voltage rating of the converter make the design of the DFIG very cost-effective. But it has limited voltage control capacity while dealing with severe voltage drops. During grid faults, an unexpected disruption of wind farms causes significant voltage variations and grid disturbances. The low-voltage ride-through (LVRT) helps the wind energy system to remain connected to the grid during severe voltage dips. Hence, LVRT fulfilment is one of the most important tasks for DFIG-based wind turbines as per the demands of the new grid codes of various countries [3]. Figure 1 presents the LVRT requirements of wind grid codes during voltage dips in various countries. Because of LVRT, the wind turbines stay connected and return to their rated value practically instantaneously after severe voltage dips. This fact has made LVRT a very active research line for the DFIG.
Testing of low-voltage ride through capability compliance of wind turbines – a review
Published in International Journal of Ambient Energy, 2018
Rini Ann Jerin A, Palanisamy Kaliannan, Umashankar Subramaniam
The guidelines for LVRT capability may vary with respect to the TSO guidelines but they can be simplified by grouping them under the categories of voltage sag tolerance, control of active power, control of reactive power, protection and power quality (Valentini 2008). These guidelines are specified with respect to the wind turbine connected at the point of common coupling. The grid codes can therefore be classified with a general category curve as shown in Figure 1 and the LVRT grid code curves of major countries with respect to wind power capacity are similar to the general category with differences in the time duration and voltage limits as per the grid codes. Before introducing LVRT capability in wind farms, the wind turbines were forced to shut down for any voltage sag caused due to faults very far from the location of wind turbines (Quitmann and Erdmann 2015). The LVRT capability is therefore provided by using advanced control in the new installations of wind turbines or with external installations such as crowbar or the Flexible Alternating Current Transmission System (FACTS) devices.