System for determining the frequency of power system for use in a protective relay operating to protect or monitor the power system

摘要

"System to determine the frequency of power system for use in a protective relay operating to protect or monitor system of power".The system (10) receives the voltages of three phases in the line of force V ~ ~ ~ B ~, V and V ~ C ~, both of a primary source location (14) or alternative location (16).The tension of local source (14, 16) selected are then applied by keys (20, 28), respectively, which are normally closed.But they are open in the case that the pole associated with each phase voltage is open.The tension of the keys closed (20, 28) are applied to a calculation circuit (40), which produces a composition of the three voltages according to a pre selected formula.The voltage output of the composite is then normalized (44) and applied to a determination circuit (estimate) of the conventional frequ00b3u00eancia (46). This output (freq.To exit) is a frequ00b3u00eancia system needs to use the relay protector.