Research On Synchronized Phasor Measurement Algorithm Under Dynamic Conditions Of Electric Power System

With the continuing development of interconnected power grid and the grid operating environment getting more and more complicated., expanding of the power grid and the increasing of the installed capacity. In order to ensure the security and stability of power system, the stability monitoring and control of power systems is more and more important. The Wide Area Measurement System (WAMS) as an important part of modern intelligent power grid, it can monitor the running state of power system and enhance the stability of power system. The Wide Area Measurement System (WAMS) was based on synchronized phasor measurement technology, How to improve the synchronous phasor measurement technology is important significance to keeping the stable operation of power grid in future. Synchronized phasor measurement algorithm, which is the core of the synchronized phasor measurement technology, in-depth study by many scholars. Although the accuracy of phase measurement can meet the most of the requirement of real time applications in the steady state. The error of phase measurement arises when a power system is under dynamic condition such as frequency deviation. Therefore, In order to improve the monitoring of WAMS performance and ensure the power system safe and stable operation, it is necessary to develop a new synchronized phasor measurement algorithm, which can still keep high precision under the dynamic conditions if electric power system. A great deal of effort has been put to there search on frequency tracking algorithm and synchronized phase measurement estimator and decaying dc components, and put forward the corresponding improvement algorithms. The thesis mainly launches from the following points:First, according to the mechanism analysis of traditional DFT algorithm error lead to frequency tracking algorithm research. Under the condition of dynamic frequency tracking algorithms are used to achieve real-time tracking of the change of the frequency in the system, reduces the error caused by the frequency deviation on subsequent synchronized phase measurement. Frequency tracking technology has played a key role in the synchronized phase measurement. In this paper is proposed based on RLS method of adaptive variable forgetting factor frequency tracking algorithm. Weighted forgetting factor to make the algorithm by adjusting the frequency tracking algorithm not only have good noise characteristics under static conditions and also has the characteristics of the fast track under the dynamic condition. Simulate the proposed algorithm in the platform of MATLAB, and compared with the traditional based on DFT recursive frequency tracking algorithm and the traditional RLS algorithm, compared the accuracy of measurement and tracking rate and anti-interference, the proposed algorithm was the best performing.Second, in terms of synchronous phasor estimation, this paper puts forward that a kind of adaptive variable window length DFT synchronized phase measurement algorithm based Compound trapezoid formula. The algorithm is based on the traditional DFT algorithm, measuring frequency precision value using the frequency tracking technology, calculate the DFT data window length, using compound trapezoid formula for Fourier equivalent transformation on the integer part data window sample point and fractional part of the data window sample point. Algorithm reduced the error caused by the frequency deviation. Simulate the proposed algorithm in the MATLAB platform, compared with the traditional variable window DFT algorithm and traditional DFT algorithm, the proposed algorithm has made great improve measuring precision.Last, in terms of elimination of the influence of dc component, based on the previous study of the synchronous phasor estimation algorithm, the paper analysis on the reason which the proposed algorithm can not eliminate the decaying dc component brings to the algorithm error influence. Aiming at the existing problem of algorithm, the paper goes on to put forward an improved algorithm, on the basis of the original algorithm, through to the adjacent three data window phase value comparison, calculates the error component of algorithm which caused by the decaying dc component, to eliminate the error influence of the algorithm which brought by the decaying dc component. Simulate the proposed algorithm in the MATLAB platform, compared with the original algorithm and the traditional variable window length DFT algorithm, the proposed algorithm not only keeps the original algorithm dynamic measurement characteristics, also can rapid filter decaying dc component.