| In the neutral point grounding system,in order to monitor the insulation,power plants,substation bus there often bear Y0 wiring on the PT.During normal operation,PT excitation impedance is very big,and three basic equilibrium,neutral displacement voltage is small.But in some brake operation or ground fault disappears,PT three-phase saturated degree difference is very big,it with the wire of electric or other equipment of stray capacitance form a resonance circuit,may stimulate the ferroresonance overvoltage of various kinds of harmonic.PT iron core saturation caused by over voltage at neutral point grounding system is the most common and most an internal overvoltage caused accidents.Non-ground neutral system is based on the ferromagnetic resonance analysis and simulation,and study the properties of the ferromagnetic resonance produced,puts forward new harmonic elimination measures "instantaneous zero impedance harmonic elimination method",and on the basis of the design and development of a system based on ARM embedded technology ferro-resonance monitoring system in power systems.It not only can real-time monitor the working state of the power grid,accurately identify the single phase grounding fault,over voltage and ferro-resonance,timely elimination of power grid frequency harmonic resonance;Moreover,the system data between control center and the RS-485 communication interface,fault information can be quickly feedback to control centre staff to establish maintenance plan as soon as possible.To ensure the safety of power grid operation,prevent the happening of the malignant accident and reduce the economic loss and reduce the production costs have important practical application value. |
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