Research And Implementation Of IEEE1588 Transparent Clock Used In Optical Measurement And Control In Smart Grid

Traditional substation connects m easurement and control equipm ent with first device through a common cable,communicates based on the analog signal,whe n measures a more signal you need to add a c onnection.In order to increase the accuracy of signal transmission,and reduce the complexity of connections,smart power grid use optical signals instead of traditional analog signals,and th ere is the need to connect optical measurement and control equipm ent with first device indirectly through the network,but at the sam e time the network connection brings synchronization issue.Currently in smart power grid synchroniza tion technologies include GP S,IRIG-B and synchronous serial mode,but they are communi cated based on dedicated data line,and can not meet the needs of network and IP.IEEE1588 is based on packet transm ission,good to meet the need of the network a nd the synchronization accu racy can achieve sub-microsecond.Implementing IEEE1588 transparent clock in network equipment,can compensate for the delay of the network equipment that connect m easurement and control equipment with first device,im prove the synchronization accuracy of the measurement and control equipm ent and first device to m eet the dem and for optical measurement and control in the smart grid.For the need of clock synchronization in smart power grid,this article introduces the theoretical knowledge a bout IEEE1588 protocol,incl uding basic concepts of IEEE1588,node classification,transpar ent clock classification,PTP time synchronization principle that clock transparent is achieved by P2 P mode or E2 E mode.Based on the principle of the trans parent clock,the main factors to affect the accuracy of transparent clock is analyzed,an conclus ion is obtained that th e crystal accuracy is the main factor to affect the accuracy of transparent clock,and an addition result shows that the accuracy of transparent clo ck can be improved by shortening the the residence delay and propagation delay when crystal accuracy is certain.This article is intend ed to im plement hardware and sof tware systems of the IEEE1588 transparent clock in network equipment.Timestamping the timing packets in hardware,and the combination of FPGA and CPU for processing synchronization messages can make transparent clock accuracy of a equipment m aintain at 10 ns ord er.In the hardware part,CPU select PowerPC83 series;MAC select chips which can report IEEE1588 timestamp in the interface between MAC and PHY;crystal selection TXCO in the high-end type,the accuracy of 4.6ppm;FPGA select Xilinx h igh-end products.The design of software systems is based on hardware,the multi-tasking and real-time operating system running on CPU is em bedded Linux,the software is based on the existing PTN software platform.The thesis analyzes the support of the use of the software platform on IEEE1588 and procession of PTP packets.The software features include the message receive and transmit module,the timestamp information extraction module,and the function of the IEEE1588 transparent clock protocol.Finally,the performance of transparent clock is tested,including three aspects such as functional testing,performance testing and negative testing.The experimental result shows transparent clock has a accuracy of about 80 ns with some fault-tolerant features to meet the application requirements.