Design Of Distribution Transformer Loss And Capacity On-line Detection System

Power distribution network is an important part of the power system,and the distribution transformer is essential equipment for power distribution network.The capacity and loss are the two important parameters of the distribution transformer,and they are also the two key indicators for evaluating the operating condition of the distribution transformer.The capacity and loss on-line detection system is used in the distribution system,the faulty transformer can be detected in time during the operating period,and this is great significance for ensuring the reliability of the power system,saving energy and improving the automatic detection level of the power distribution network.At present,the off-line detection method has been used in the power system to calculate the capacity and loss of the distribution transformer,but the transformer can be tested only in the time of periodic maintenance,therefore it is impossible to find the faculty transformer in time.Since the voltage on-line detection for high voltage side of the transformer cannot be solved,the existing on-line detection technology mainly focuses on the partial discharge detection,insulation dielectric loss detection and so on.For the research of capacity and loss on-line detection,it has some problems such as the large deviation between the calculated and the actual value,and it is impossible to distinguished between the on-load loss and the load loss of the distribution transformer.According to the above problems,bases on the short circuit impedance calculation,and the real-time voltage and current detection for the primary and secondary side of the transformer,this thesis proposed an improved short circuit impedance on-line calculation method,and designed an on-line capacity and loss calculation method.In additional,an on-line capacity and loss detection system for the 10kV distribution transformer has also proposed in this thesis.Selection of sensors,the signal processing circuit,the A/D conversion circuit,the CPU circuit,communication circuit and the power supply circuit are included in the lower computer of the on-line detection system include.The upper computer of the on-line detection system is designed by the LabVIEW software.The datas which transmitted from the lower computer can be received and calculated.The calculation results,such as the value of voltage,current,capacity,loss and other parameters can be displayed in the upper computer interface.Moreover,the working status of the distribution transformers can be evaluated by using the on-line detection system,and the faculty transformers can be find in time by using this system,then the staff can be notified to repair and replace the faculty transformers.In order to verify the correctness of the on-line calculation and the feasibility of the on-line system which proposed in this thesis,the on-line detection system is used in the experiment platform for experiment.The experiment results show that,the capacity and loss which are given by the on-line detection system is good agreement with the actual working state of the distribution transformers.