Title :
Control and testing of a dynamic voltage restorer (DVR) at medium voltage level
Author :
Nielsen, John Godsk ; Newman, Michael ; Nielsen, Hans ; Blaabjerg, Frede
Author_Institution :
Vestas Wind Syst., Ringrobing, Denmark
fDate :
5/1/2004 12:00:00 AM
Abstract :
The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags. Implementations of the DVR have been proposed at both a low voltage (LV) level, as well as a medium voltage (MV) level; and give an opportunity to protect high power sensitive loads from voltage sags. This paper reports practical test results obtained on a medium voltage (10 kV) level using a DVR at a distribution test facility in Kyndby, Denmark. The DVR was designed to protect a 400-kVA load from a 0.5-p.u. maximum voltage sag. The reported DVR verifies the use of a combined feed-forward and feed-back technique of the controller and it obtains both good transient and steady-state responses. The effect of the DVR on the system is experimentally investigated under both faulted and nonfaulted system states, for a variety of linear and nonlinear loads. Variable duration voltage sags were created using a controllable LV breaker fed by a 630 kVA distribution transformer placed upstream of the sensitive load. The fault currents in excess of 12 kA were designed and created to obtain the required voltage sags. It is concluded the DVR works well in all operating conditions.
Keywords :
fault currents; feedback; feedforward; power distribution control; power supply quality; power transformers; transient response; voltage control; 10 kV; 400 kVA; 630 kVA; controllable LV breaker; distribution test facility; distribution transformer; dynamic voltage restorer; feedback technique; feedforward technique; high power sensitive loads; low voltage level; medium voltage level; steady-state response; transient response; voltage sags; Costs; Feedforward systems; Low voltage; Medium voltage; Power quality; Power system protection; Test facilities; Testing; Voltage control; Voltage fluctuations; DVR; Distribution transformer; dynamic voltage restorer; medium voltage; power quality; voltage sag;
Journal_Title :
Power Electronics, IEEE Transactions on
DOI :
10.1109/TPEL.2004.826504