Online Identification And Suppression Of Low Frequency Oscillation In Power System Based On WAMS

ABSTRACT:With the continuous development of economy and the power system expanding, interconnection can optimize the allocation of the nationwide power resources more efficient, but the interconnected network also has its disadvantages. As the power grid interconnection speeded up, there are some weak network transmission lines, induced sustained low frequency oscillation(LFO), posed a great threat to the stability and completeness of the power system. Surveys of accidents of power system show that LFO has become the main factor that affects stability. Once LFO occurs, it will threat the security and stability of the grid seriously, even may trigger a cascade failure which can result in serious consequences. Therefore, it is of great significance to fast suppress LFO in power system.Along with the improvement of Phase Measurement Unit (PMU) and Wide Area Measurement System (WAMS), the development of the power system was elevated to a new height. WAMS monitors the power system in real time with high precision. Applying WAMS in the power system, analyze the stability of power angle and identify on-line with the real-time data provided by WAMS. This provides an effective tool for us to study the problem of LFO.As a time domain method analyzing actual measurement data, in the study of LFO in power system, Prony algorithm can extract oscillation feature effectively, identify the oscillation modes, calculate the oscillation frequency. This is one of the main methods of identification in LFO. This paper proposes a method based on Prony algorithm to identify LFO online and apply Power System Stabilizer (PSS) for rapid suppression. When LFO occurs in the system, apply Prony algorithm to analyze the power angle provided by WAMS, it can identify all kinds of LFO modes online. For each mode, PSS would be rapidly configured and applied into the system. When some LFO modes are successfully suppressed, the corresponding PSSs exit. Taking the10-generator-39-bus system of New England for example, it verifies the correctness and effectiveness of the proposed approach in identification and suppression of LFO.