Limiting Distributed Generator Capacity Due to the Voltage Stability Phenomena

Voltage stability problems were originated by the high use of the existing transmission lines, which was made possible through the installation of reactive compensation devices. Maximum power transmission and inadequate voltage control are the two main aspects associated with voltage stability analysis. Nowadays, it is well-known that there is a maximum power that the network can transmit to a load bus. However, it is not familiar to many that there is a maximum power that can be injected by a generator into the network while keeping proper voltage control. The problem addressed in this paper is the opposite relationship between the generator excitation voltage and the controlled voltage when near by transmission / distribution network is heavily loaded. The phenomena is prone to occur in the new scenario of distributed generation connected to already existing low voltage networks. Therefore, the capacity size of a new generator may have to be limited in order to assure correct voltage control. Illustrative real life numerical examples with the Brazilian system are provided