Study Of Optical Current Transformer And Its Interface To Substation Automation System

As important equipment of relay protection and electric energy measure in power system industry,current transducers play a primary role for working well and calculating precisely in power supplying system.Economical and secure operation of power system is closely related with precision and dependability of current transducers.With the development of national economy,the new grade of voltage of power supply is improving constantly, the systematic measurement and precision of protection demand to be improving constantly, the traditional electromagnetic current transducers expose the shortcoming that can't be overcomed, the active optical fiber current transducers is the new-type optical and electronic current transducers which incorporate electronic technology and optical technology into an organic whole, its characteristics, such as high accuracy,high dependability,wide bandwidth ,etc.And it have already become the substitute of the traditional electromagnetic current transducer in power industry gradually.In order to satisfy the demanding for electric current transducer in moden electric power industry, this issue designed a hybrid fiber current transducer that can work well and at the same time, coincide with the rule of international standard. We use Rogowski coils as the sensor that mounted on high voltage power line. After converting Rogowski coils's analog signal to digital signal, we transmit the digital signal to low voltage part through POF where finish the tasks of measurement. It can realize digital and analogical output respectively according to the requirement.The whole circuit's timing generation and synchronization was realized with CPLD.As the channel of data transmiting, POF can isolate high voltage part and low voltage part efficiently. Throw the powerful function of the DSP chip,it can realize functions such as digital integral and digital filter for the signalIEC 61850 is the first communication standard targeting system automation among power stations. It adopts Object-Oriented (OO) technology and has an open-end infrastructure to accommodate future developments. Its major objective is to achieve interoperability of Intelligent Electronic Devices (IEDs) from different manufactures IEC 61850-9-1 defines the communication service between the electrical transducer's MU (Merging Unit)and IEDs served in the bay level.Synchronization of MU is critical to guarantee accuracy and correction action of relays. This paper discusses a new method to sync data among MUs followed by IEC 61850.Application of active optical fiber transducers must be causing fundamental changes of the substation automation model.