A series dynamic resistor based converter protection scheme for doubly-fed induction generator during various fault conditions

Abstract

Abstract-This paper proposes a new converter protection method, primarily based on a series dynamic resistor (SDR), that avoids the doubly-fed induction generator (DFIG) control being disabled by crowbar protection during fault conditions. A combined converter protection scheme based on the proposed series dynamic resistor and conventional crowbar is analysed and discussed. The main protection advantages are due to the series topology when compared with crowbar and DC-chopper protection. Various fault over-current conditions (both symmetrical and asymmetrical) are analysed and used to design the protection in detail, including the switching strategy and coordination with crowbar, and resistance value calculations. PSCAD/EMTDC simulation results show that the proposed method is advantageous for fault over-current protection, especially for asymmetrical faults, in which the traditional crowbar protection may malfunction.Index Terms-Series dynamic resistor (SDR), converter protection scheme, doubly-fed induction generator (DFIG), fault ride-through (FRT), wind power generation.

Comparison of Crowbar Control and Novel Control Methods for DFIG Wind Turbine to Enhance LVRT Capability under Various Faults

“…But, the dc-link voltage is likely to be fluctuated during this period and this will affect the rotor current control [7]. In active crowbar control scheme [4] the crowbar resistance is connected when necessary and thus reduces the duration of its usage. In SDR method this a dynamic resistor is put in series with the rotor and this limits the over current in rotor.…”

Introduction to the Doubly-Fed Induction Generator for Wind Power Applications

“…It is also used as protection for the DC-link capacitor in full rated converter topologies, for example, permanent magnet synchronous generators. In a similar way to the series dynamic braking resistor, which has been used in the stator side of generators, a dynamic resistor is proposed to be put in series with the rotor (series dynamic resistor) and this limits the rotor over-current (Yang et al, 2010). Being controlled by a power-electronic switch, in normal operation, the switch is on and the resistor is bypassed; during fault conditions, the switch is off and the resistor is connected in series to the rotor winding.…”

“…John Fletcher and Jin Yang (2010). Introduction to the Doubly-Fed Induction Generator for Wind Power Applications, Paths to Sustainable Energy, Dr Artie Ng (Ed.…”

Reactive Current Assignment and Control for DFIG Based Wind Turbines during Grid Voltage Sag and Swell Conditions

“…The most commonly accepted technical solution applied in engineering can be summarized as follows: 1) for a mild voltage dip, only modified control strategies for grid-side and rotor-side converters (GSC and RSC) are applied, such as the flux demagnetizing approach [10]; 2) for a depth voltage drop, additional hardware devices, such as resistances connected in parallel with the RSC (the so called crowbar [11], [12]) or with the dc-link capacitor (the so called chopper [13]). On the one hand, they are equipped to suppress the inrush currents through the converters; on the other hand, the DFIG systems should be controlled to inject reactive current into the grid as soon as possible [3].…”