Schutztechnik in Elektroenergiesystemen

Distance Protections in the Power System Lines with Connected Wind Farms

“…Dynamic states analyses must take into consideration the fact that present wind turbines are characterized by much higher resistance to faults (voltage dips) to be found in the power system than the conventional power sources based on the synchronous generators. A very important and useful feature of some wind turbines equipped with power converters, is the fact that they can operate in a higher frequency range (43 ÷ 57 Hz) than in conventional sources (47 ÷ 53 Hz) (Ungrad et al, 1995). Dispersed generation may have a positive influence on the stability of the local network structures: dispersed source -distribution network during the faults.…”

“…They take advantage of currents and/or phases comparisons and use of pilot communication lines. However, they are usually used in the short-length lines (Ungrad et al, 1995). The presence of the DPGS (wind farms) in the HV distribution network will affect the impedance criteria especially due to the factors listed below:…”

“…The phase of load usually changes from cosφ = 0.8 ind to cosφ = 0.8 cap . The expected Z pmin can be determined by the following equation (Ungrad et al, 1995), (Schau et al, 2008):…”