Research On Online Monitoring And Disturbance Locating Of Low-frequency Oscillation Based On WAMS

With the expansion of the internet-scale of the grid, the operating characteristics of the network become increasingly complex. Therefore, power system analysis and control has become increasingly difficult. Low-frequency oscillation caused by system interconnection has become an important factor endangering the safe operation of the grid and constraining power transfer capability. In recent years, two forms of low-frequency oscillation including negative damping mechanism and forced resonance mechanism has occurred many times in our country.In view of the new features of the Low-frequency oscillations in the actual power system and considering the new control techniques appeared currently such as WAMS applications, this paper carries out further research for real-time control techniques of low-frequency oscillation starting from online decision support and disturbance source positioning. The main work and results of this study are summarized as follows:(1) Based on pattern matching ideas, dynamic stability control strategy generated by small interference calculations and the sensitivity analysis is applied to the actual low-frequency oscillations. This paper studies the Prony. QR, IRA algorithm and eigenvalue sensitivity theory used in the time domain and frequency domain, proposes the criteria of the pattern matching and the calculation method of the real-time mode shape, analyzes the factors affecting pattern matching and gives corresponding countermeasures.(2) Against the issue of force resonance mechanism low-frequency oscillation, from two angles including the mechanical disturbance propagation velocity and electromechanical distance contour, this article proposed the disturbance localization method based on time delay of electromechanical wave which can be expressed by space-time matrix. On the basis of previous studies, this paper compares the characteristics of the energy function in the transient cases including short circuit, cutting machine, load shedding and small persistent periodic disturbance, explores the mathematical criterion of positioning the disturbance source based on energy function, and shows the implementation processes of three kinds of disturbance source location method including electromechanical wave time delay, transient function and hybrid dynamic simulation, which are compared and analyzed from different angles (3) Based on PSD-BPA, PSD-SSAP and MATLAB,4-machine2-zone system, New England10-machine39-bus system and a certain real power system are applied to simulate and vertify the correctness of the above process. Parts of the content of disturbance localization are implemented based on C++. The principle method will get practical application in the low-frequency oscillation prevention and control system in Henan Province.