The Research Based On MATLAB For Fault Type Identification And Controlled Fault Interruption

In the process of breaker synchronously interruption of multi-phase fault, if the fault type and fault phase can be exactly distinguished, then the synchronous short-circuit interruption technique is used to electric current of fault phase and short-circuit interruption moment of contact terminal of breaker is controlled, the electric current of electric arc through the zero point in optimum combustion time of the short-circuit interruption process. This controlled fault interruption can efficiently reduce the average combustion time of electric arc of contact terminal and peak value of electric current so that the capacity of short-circuit interruption of contact terminal can be increased and the abrasion of contact terminal can be reduced. Because of mutual coupling of three-phase system, after the interruption of the first short-circuit phase, the zero point of electric current of remainder fault phases will shift. Then the strategies of controlled fault interruption will be influenced and changed. Different fault types correspond to different controlled fault interruptions of fault electric current. To identify system fault type and fault phase quickly and accurately is the primary point of controlled fault interruption of multi-phase fault electric current.In order to select fault phase in the process of synchronously interruption quickly and accurately, the relationship of positive sequence and negative sequence based on correlation analysis for the phase position is presented in this dissertation. And the relationship of phase position is used to verify the fault phase rapidly and exactly. The phase relation of order sub-value of fault electric current can be obtained and fault type and fault phase can be determined according to relation of phase, finally the identification of fault phase can be realized.When the fault type and fault phase is determined, an adaptive, self-checking algorithm to the phase of needing short-circuit interruption of high voltage alternating current circuit-breakers is adopted to realize controlled short-circuit interruption of fault electric current. The primary object of controlled short-circuit interruption is extracting the parameter of fault electric current quickly and predicting the zero point of fault electric current exactly in extinguishing of electric arc. Thereby this method is seeked to reduce the electrical stress and wear on the interrupter. The strategy of controlled fault interruption of breaker proposed by this thesis adopts different control procedure to avoid undue prolongation of the total fault clearing time and so on in handling fault. The adaptive, self-checking algorithm can effectively identify and detect the initial phase angle and realize quickly track to fault electric current so that predict the zero point of fault electric current in extinguishing of electric arc when short-circuit interruption and control the interruption of contact terminal in the optimum interval of combustion arc.In order to evaluate the influence of initial phase angleα, attenuation time constant of DC sub-valueτ, white noise and respond time of relay protection on controlled short-circuit interruption algorithm of multi-phase fault electric current, this dissertation in the basis of theory analysis adopts MATLAB to establish synchronous interruption model of multi-phase fault and make large numbers of simulation. And the practical fault wave of power system is adopted to verify the performance of algorithm. The simulation results demonstrate that the select-phase algorithm can exactly identify fault type and fault phase of specifically condition in the half-cycle of fault happening. And in the responding time of relay protection, the control interruption algorithm of fault electric current can better predict the zero point of electric current of object in low sampling frequency. The maximum error value of predicted zero point is all in±1ms and the controlled algorithm also have better anti-jamming ability to white voice of environment and the energy of combustion arc can be saved 20%-50%. So the dissertation provides theory basis and realization foundation for synchronous interruption of multi-phase fault electric current of breaker.