System Of Optical-Electrical Current Transformer With Laser Power

Optical-Electric current transformer (OECT) is a new-style electric equipment ,because of the sensing method differences between OECT and traditional current transformer (CT),OECT have much advantages than CT, and which makes OECT would have been wildly used in future power system. OECT is divided into active and passive two types. From IEC standards on OECT, different methods for designing Active-optical current transformers AOCT) are compared ,and the one based on analog to digital conversion is chosen. This method can get high precision and short delay time. Furthermore, principle schematic of AOCT is given, its main parts and their functions are introduced.In this paper,First, the high voltage circuit for current transformer is studied .In consideration of reducing of power in primary circuit, this paper use transmission with single optical fiber to fulfill data sending and receiving, so its principle is outlines firstly .Then it comes the details of how to fulfill data-receiving and decoding accordingly in secondary circuit with CPLD (Complex programmable logic device).Data processing is based upon DSP system. This paper introduces the technology how to synchronize three-phase sampling, and puts emphasis on the function of synchronization with GPS. the thesis describes the analog output part , introduces the standard IEC61850-9-1, gives a brief introduction about the communication between the transformer and the computer in order to acquire the standard digital output, and then gives the solution to the digital output according to the standard.The question of power supply in the high voltage side of the OCT is a very important part in the design of transformer, which can determine whether the whole system can work rightly or not. This paper discusses several methods of power supply and then adopts the method whose power supply was provided by laser. This paper describes the working characteristics of the key apparatus LD,and deeply researches the drive circuit, protection circuit and temperature controlled circuit.