Developing a New Out-of-Step Protection
This paper presents a new type of out-of-step relay, which responds to the phase angle between two voltages.The performance of this relay on impedance diagram is represented by six circles. A logic of picking up step by step is adopted. High reliability is obtained on account of its" 5 out of 6" tripping crite- rion.It can be picked up before the voltage of electrical center crosses zero. Power swings with shorter Period can be detected.Simple circuitry and conven- ient setting make it much easier to manipulate.