Tap Changer With Contactless On-load Regulating Voltage For Distribution Transformer

Under the condition of the reactive power of the power system,the automatic voltage regulation of the distribution transformer is the most direct and effective measure to stabilize the low-voltage distribution system.The traditional mechanical contact switch(OLTC)due to action of arc,it is not suitable for distribution transformer need frequent voltage use,and in the research stage of contactless OLTC although no arc and action frequent moves,but there are still the following problems: in the existing power electronic components of low voltage next,only on the N%5± U joint realization of load voltage,voltage range small,can not meet the requirements of engineering;control system of contactless OLTC research now is located in the low voltage side of transformer,switch as controlled object is in a high pressure side actuator,when operation of high-voltage side arrester or high voltage single phase grounding when the OLTC control system for high pressure and breakdown;tap transform process,easy to produce a large circulation,resulting in a switching element or regulating winding breakdown due to over-current;there is no effective.Protection measures,when there is a lack of phase,overcurrent,tap switch breakdown and other faults,the transformer will stop running,low power supply reliability.These problems restrict the application and promotion of non-contact OLTC.To solve these problems,this paper designs a kind of contactless OLTC,the device adopts the anti parallel thyristor module as the switch actuator,with positive and negative voltage regulating voltage,to expand the regulator;power control system and voltage measurement through the isolation transformer from distribution transformer primary side near the neutral side of the regulating winding ends,the control system of suspension,solve the problem of pressure;while the high pressure side of the regulating winding non rated tap connected with the thyristor module between the series three-phase automatic air switch contacts,when over current action,the over-current protection function;and each three-phase air switch third on one side of the contact and isolation transformer windings connected in series,when the lack of phase,overcurrent,tap off close the breakdown fault,automatic air switch tripping rapidly,cut off the power supply control system,automatic exit control system,SCR module and rated tap connected with passive trigger mode,the control system due to power out of work when the module is conducted,and non rated file SCR trigger signal will be lost in the closing off state,and then make the transformer at rated stall normal operation,to ensure the reliability of power supply.Based on the existing facilities of laboratory and Harbin geruige power equipment companyas the basis,analyzed the OLTC monitoring unit debugging,OLTC trigger circuit test,prototype test and prototype of automatic voltage protection test.The experimental results show that with contactless OLTC distribution transformer during normal operation,according to the fluctuation of network voltage,automatically adjust the load output voltage and keep the voltage in the range of standard(N?%3 U),and the pressure to expand the scope toN?%10 U;and in the case of switch fault,air switch tripping rapidly.OLTC transformer function exit,automatic recovery to the rated stall continue power supply operation,realize the protection of the regulating winding and ensure the reliability of power supply functions.