| With the great advances of computer technology, automatic technology and network communications, power system becomes more automatic than ever. At the beginning of this century, European countries and USA put forward the concept of "smart grid". The State Grid Corporation of China also started construction of the smart grid in 2009. The government and society pay more attention to the smart grid, and the smart grid is the development trend of power system. Digital substation is an important part in smart grid。Electronic transformer is very important and necessary to digital substation, whose characteristics and operation are quite different from conventional current transformer of voltage transformer. For the safe and steady operation of digital substation and smart grid, it is of great significance to make more intensive research on electronic transformer.This thesis carries out some related studies about the active Electronic Current Transformer (abbr. ECT) which has caused widespread concern. Based on plenty of references from home and abroad, the thesis makes thorough study on the transient characteristics and signal processing circuit of ECT. Then the thesis explores the modeling method of ECT's merging unit information model and wind generator information model in digital wind farm.The present study about ECT focuses on steady state performance. People explore all ways to improve the measurement accuracy. However, practical application implies that the integrator in ECT's signal processing circuit could infect the transient performance significantly. This thesis establishes mathematical model of the ECT's sensor, and analyses the influences of the integrator structure and parameter on ECT's transient performance by way of digital simulation. The thesis advances a method to find appropriate integrator parameters. Based on the result, the thesis designs a set of sensor with integrator. Experiments demonstrate that the sensor has excellent steady performance and transient performance, which means that the sensor can be applied in power system dynamic simulation research.Aiming at improving ECT transient performance and anti-interference ability, and also aiming at find better ways to solve the sampling synchronization, the thesis invents a new signal process method for Rogowski-coil based ECT. The thesis also discusses thoroughly some essential technologies to implement the new method. By means of artful counting, the method merges ideal integrator and analog-digital converter in VFC process, which makes the sensor acquire excellent transient performance and cancel the fiber for sampling synchronization. The method can simplify the sensor circuit and improve the sensor reliability.Dynamic simulation experiment (abbr. PSE) is very important for relay research and electric transient modeling. Applying magnetic current transformer (abbr. MCT) in PSE may affect simulation parameter, thus the research result can't be applied to active environment. Because of MCT's saturation, distorted waveform used in research isn't the true wave produced by electric equipment, which may make the research more difficult. The thesis build up a set of measure system comprised of ECT for PSE, and some experiments has been carried on. The thesis compares the waveforms produced by MCT and ECT, and result suggests that ECT is very suitable and important to PSE.As a kind of good practical renewable energy, wind power develops rapidly in recent years. Wind farm's digital substation is the only interface to power utility, whose operation is important to wind farm's operation. Merging unit is a key device for transmitting samples, which is very important for applying ECT in power system. Most merging units in trial operation are developed according to IEC61850-9-1 or part of IEC61850-9-2, which means that the merging unit can only transmit samples and can't receive commands. In the view of digital substation, the thesis analysis requirements for merging unit. Then the thesis focuses on establishing information model and information exchanging model of merging unit, which makes merging unit acquire the ability of full-duplex communication. In this way, the merging unit can online receive commands from other devices.Most supervisory and control system for wind farm are developed by wind generator manufacturer separately. It brings inconvenience to the wind farm construction and operation management. Referencing the "top-down" concept in computer software engineering, and according to IEC61400-25 standard, the thesis establishes a integrated information model of wind generator. The thesis also studies the merits and shortcomings of five SCSM defined in IEC61400-25. Involving the SCSM-MMS defined in IEC61850 standard, wind farm supervisory and control system can communicate with substation SCADA system seamlessly, which is the trend for future wind farm.All research results are summarized finally and the direction of further research are pointed out.
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