A method and apparatus to protect the turbine generator hazard of the transmission system subsynchronous resonance

摘要

This invention relates to a method by means of which a turbine generator (1, 2, 3) can be protected against subsynchronous frequencies occurring in an electric network which is connected to the turbine generator and which incorporates capacitors. The method is based on de-equalizing the subsynchronous natural frequencies of the three phases, so as to weaken the coherence of the frequencies. This is achieved by incorporating in each of two of the phases a respective inductance L of mutually different size and by changing the capacitance equivalently with a series capacitance C such as to fulfill the condition 1/LC = omega 2_o, where omega o is the network frequency.