An Excitation Mode Analysis Method for Multi-Machine Systems Based on Minimum Characteristic Loci

Application of power system stabilizers (PSS) is currently the most effective and economical way to suppress low-frequency oscillations. The principle of PSS suppressing low-frequency oscillation is to compensate the lag phase of the excitation system and provide positive damping to the system. Generally, the greater the gain of PSS, the greater the positive damping provided. However, according to the engineering experience, the gain of PSS cannot be increased indefinitely. When it is increased to a certain extent, the excitation voltage will occur a continuous oscillation. In this paper, an analysis method of excitation oscillation mode is proposed based on minimum characteristic loci. The solution equations of excitation mode oscillation frequency and PSS critical gain are given.