Research On Design And Control Method Of Votage Energy Source Based On Current Transformer

With the construction of China’s strong smart grid,the number of high-voltage transmission and distribution lines are increasing.As a carrier of electric power,transmission and distribution lines occupy a very important position.Due to the harsh natural environment,the line is prone to failure.If the fault is not handled in time,it is very likely to further expand the scope of accident,reduce the reliability of power supply,and affect the stability of the operation of the power system.Transmission lines monitoring relies on online monitoring equipment and various online monitoring technologies.The state information of the transmission line is obtained through a large number of distributed sensing and measuring devices,which require the monitoring equipment to have stable power supply for its normal work.However,the traditional power supply can not meet the complex geographical and climatic conditions.Therefore,it is of great signigicance to study the power supply of the transmission line’s online monitoring equipment.In this thesis,firstly,the design principles of several common power supply methods at domestic and foreign is introduced and emphasis the development status and feasibility advantages of power source based on current transformer.The problem of taking energy is that the first current is too large or small.The corrective measures are analyzed and verified through analyzing the principle of electromagnetic induction.Secondly,based on the topology of the current transformer,the theoretical analysis of the output power is come true.Combined with Matlab/Simulink simulation software,the output power without considering saturation characteristics,paralleling capacitance of auxiliary side and considering saturation characteristics are simulated and analyzed respectively,and the relationship between the maximum output power and primary current,secondary winding turns and load was obtained.In the design of DC voltage source based on current transformer,the operation mechanism and control method of rectifier circuit,bleed circuit,DC chopper circuit,protection circuit and battery charge and discharge circuit are introduced respectively.Each part of the circuit is modeled in the Matlab/Simulink simulation platform to form a DC power supply based on current transformer.By changing the magnitude of the primary current to simulate the case where the bus current is too large or small in actual operation,the output voltage in the four operating conditions is simulated and analyzed.In the design of AC voltage source based on current transformer,the output voltage is directly processed by the principle of AC chopping.The third auxiliaty winding is added on the secondary side of the current transformer to form the control of the regulated ACpower supply.A control algorithm based on polynomial least squares curve fitting function is proposed.The simulation model is built by deriving the output voltage,which consider the influence of load variation,fit the voltage regulation function,and output the duty cycle of the gate signal for switching control directly.The steady state characteristics,the transient characteristics and the influence on the the transmission line are simulated.The simulation results indicate that the method not only can adapt to various operating states of the transmission line well which can maintain a stable output voltage while changing the current,but also has little influence on the transmission line itself.