The implementation of the low voltage ride-through curve on the protection system of a wind power plant

Abstract

This paper presents the implementation of the low voltage ride-through (LVRT) curve in two commercial numerical relays, assessing the features and limitations of each protection device. The LVRT curve is defined in grid codes of several countries, especially those who already have or are planning a high share of wind power in their electric power systems. The functionality of the wind turbine grid protection system is tested in a power system using the PSCAD/EMTDC simulation tool. The fault ride through capability curve applied in the test system is as defined in the Brazilian grid code and the protection system responses evaluated at the point of common coupling of the wind power plant when the power network is under symmetrical and unsymmetrical faults. The biggest challenge to adhere the system operator requirements is to ensure the highest conformity to the defined LVRT curve, because most relays only gives you the option of tuning in discrete time intervals.