Optimum Modelling of Damping Coefficient and its Settling Time for a Large Hydro Alternator: A Case Study on impact of Non-Electric Dynamics

摘要

Hydro alternators plays a vital role in generating low cost power since it involves no further investment on energy source and system replacement. In most of the developing countries, this low cost power generation plays vital role in balancing the energy markets in terms of its economic operation. But, owing to its large installation capacity, the alternators possess huge rating and size. As the rating and the size increases, the machine start and stop procedure pro-longs and hence the term stability is attained after a minimum period of start of generation. This is due to the high inertia constant and in detail due to the lack of synchronization which leads to excessive damping of the entire system. And hence optimal design of the damping coefficient ( K_D) is desired in order to bring the system to stability. The K_D directly depends on the respective damping coefficient design of Automatic Voltage Regulation (AVR) and the Power System Stabilizers (PSS). A small signal stability experienced by such systems may be due to two reasons a) Due to Electric Dynamics (ED) b) Due to Non-Electric Dynamics (NED). The former is a most common phenomenon and is most widely monitored. But the latter is often discarded in majority of the stability analysis. Earlier studies have pinpoint results on the impacts of NED on the stability of the system. And hence, a joint research analysis on optimal modeling of the damping coefficient and the impacts of NED have scope in the installed systems. The work presented here concentrates on two thing a) optimal model-ling of the K_D and later optimally reducing its settling time using constrained optimization technique b) upon the designed value of K_D the impact of NED is studied and inference is discussed. The entire work is carried out by taking a large hydro-alternator of 66.67MVA which is installed at a Hydro Electric Generating Station located in India. The alternator is optimally modeled using dynamic equations and then the settling time is further optimized. Later the developed model is taken out for analysis of NED. The work is carried out in MATLAB Simulink Platform.