Bifurcation theory deals with the change of qualitative behaviour in a parameter space of dynamical systems. This study investigates the bifurcation phenomenon of an industrial drive having typically constant speed requirement for which pulse-width modulated inverter fed cage induction motor (IM) is a good choice. The focus is on bifurcation analysis of the stator voltage controlled IM drive, with a particular emphasis on the dynamics and stability under variations of load torque and proportional integral controller gain. Extensive computer simulations are performed to capture the system's dynamic behaviour and demarcate the bifurcation boundaries. Trajectory and Poincaré section before and after the bifurcation are shown. The detailed mathematical model of the closed-loop system is derived and is used to analyse the observed bifurcation phenomena. The describing equations reveal that the system loses stability via supercritical Hopf bifurcation. Experimental results are also provided to confirm the theoretical analysis.
It is well known that Load Frequency Control (LFC) model plays a vital role in electric power system design and operation. In the literature, much research works has stated on the advantages and realization of DR (Demand Response), which has proved to be an important part of the future smart grid. In an interconnected power system, if a load demand changes randomly, both frequency and tie line power varies. LFC-DR model is tuned by standard controllers like PI, PD, PID controllers, as they have constant gains. Hence, they are incapable of acquiring desirable dynamic performance for an extensive variety of operating conditions and various load changes. This paper presents the idea of introducing a DR control loop in the traditional Multi area LFC model (called LFC -DR) using LQR- Fuzzy Logic Control. The effect of DR-CDL i.e. (Demand Response Communication Delay Latency) in the design is also considered and is linearized using Padé approximation. Simulation results shows that the addition of DR control loop with proposed controller guarantees stability of the overall closed-loop LFC-DR system which effectively improves the system dynamic performance and is superior over a classical controller at different operating scenarios.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.