The Research Of Multiband PSS4B Parameters Setting

The high speed development of economy is the booster of electric powergrowth，which increases more demand of power, while leading wide development ofelectric power construction. In some cases that positive damping caused by generatorsand excitation systems cannot compensate the negative damping caused by powersystems, the low frequency oscillation will occur in the relatively weak systemconnection part. With yearly rapid expanding of power system and development ofregional interconnected grid, the low frequency oscillation becomes the prominentissue and important reason for leading system instability.Power System Stabilizers(PSS) is the most financially and effective measure torestrain system low frequency oscillation. Facing the tendency of interconnectionpower grid, the request for PSS is developed, such as compensating for more widefrequency band to restrain more oscillation modes as the same. A lot of scholarsresearch about new type multi-band PSS for meeting the demand of interconnectionpower grid development. This paper focuses the research on a new kind of multi-bandpower system stabilizer named PSS4B which can restrain more oscillation modessamely and easy for setting. PSS4B has a broad applying prospect, however itsparameter setting is relatively difficult, so related rearch is still less.This paper gives alot of theory analysis and the details of parameter about setting in a specificeight-machine system.Based on six-order model and technology of GMR/PMT, and considering theuncertainties and disturbances existed in power systems normal performance, systemelectromechanical oscillation mode is changing. In order to improve the stability ofmultiple operation modes of the systems, the theory of probability is introduced inthis paper to analysis the stability of power system. Probabilistic sensitivity is appliedto confirm the concrete located position. From the practice requirement, with multiplysystem operating conditions considered in this paper, the phase compensationapproach is used to determine lead/lag time constants, and the root locus method is applied to confirm gains. Based on the probabilistic eigenvalue analysis, parametersof PSS4B are determined by probabilistic sensitivity analysis, while the influencesamong PSSs have been partly considered.Based on an eight-machine24-node system and taking720kinds of systemsfrom eight-machine system as a sample constructs the probabilistic environment. Thestatistical properties of real part of characteristic roots, expecting that damping ratioand variance can be characterized by analyzing the probabilistic sensitivity roots.Without PSS, the original seven oscillation modes cannot meet the requirements inmulti-mode running system. After using this proposed method setting PSS4Bparameters, the probability of the characteristic roots indicators meet the robuststability requirements, stability of seven oscillation modes and damping ratioimproved. The results prove that installation of six PSS4B can provide an effectivedamping of the oscillation modes and has strong adaptability and versatility.