Research On Remanence Variation And Inrush Current Suppression Of Transformer

In the collective effect of steady-state periodic components,transient biasing and steady-state remanence,the transformer may be saturated when it’s closed with no-load,and will result in a large peak inrush current.not only does the inrush current l-ead to the relay protection malfunction,but also resulting grid voltage drop,harmo-nic pollution,and inrush current,ferromagnetic resonance overvoltage and resulte in negative impact to the power system’s operation.Over the years,there are two ways to suppress the inrush current:inhibition and recognition.but still there are flaws in the existing methods,or there are areas where improvements can be made.In this paper,the suppression of transformer inrush current research,for the existing problems:(1)transformer remanence measurement(2)circuit breaker closing angle accuracy of two aspects to start.According to the results of dynamic model experiment,a set of ripple angle relationship of surge suppression is found,and an improved phase selection control circuit breaker technology is proposed.The technology greatly reduces the exact requirements of the circuit breaker closing,although it can not completely suppress the occurrence of inrush current,but the peak value of the surge in the allowable range,greatly reducing the impact of the inrush current to the system,but also enough to avoid the protection of the malfunction.For the problem of measuring transformer remanence,in order to make the transformer core flux prediction has engineering practicality,transformer core magnetic flux and current amplitude and phase angle in transformer opening time must be associated.This paper presents a scheme to measure the remanence by using the first peak current of the inrush current.The scheme combines the DC magnetization curve and the peak magnetization curve to find the remanence before the transformer turns off.