Deepak Kumar Gupta

PSS tuning with firefly driven knowledge domain-a smart control concept

This paper presents the tuning of power system stabilizers (PSS) with Firefly driven knowledge domain states mapping in multi area power system. Tuning of PSS parameters has been done by Firefly algorithm (FA) by minimizing performance indices as an objective function. Tuning of PSS parameters by FA have been done in offline mode at different operating conditions such as dynamic load change. The objective function for tuning the parameters of PSS is integral time multiplied by squared error (ITSE). These sets of tuned parameters at different operating conditions are termed as knowledge domain. The states response violates from desired limits as the dynamic change in the system operating conditions occurs. Retuning of controller parameters have been done straight away from the respective knowledge domain to provide precise damping of signals of interest as quick as possible. The process is viewed as knowledge domain mapping. The system study has been performed on six area sample power system developed with UPFC connected between area two and three and PSS to rest of all the areas. The proposed concept demonstrates auto tuning of PSS for quick oscillation damping as the operating condition changes.

A server side caching scheme for CORBA

We propose a caching scheme for saving the results of invocations of read methods at server side. Server side caching helps in reducing load on frequently accessed servers when computing the result is relatively costly. Our model provides strong consistency by using a dependency graph that specifies dependence information among method invocations of an object. We have implemented this scheme as a service in CORBA.

Modified-multi stage LQR (M-MSLQR)UPFC controller for inter-area oscillations damping-design and analysis

This paper presents analysis and design of modified-multi stage LQR (M-MSLQR) unified power flow controller (UPFC). A systematic analysis of M-MSLQR UPFC has been presented utilizing state space model developed in the generalized framework for two area system. An improved design concept is proposed as M-MSLQR UPFC over MSLQR which results in relatively low peak overshoot/undershoot and settling time of all states. The proposed controller considers state predominant approach with real part as well as the imaginary part of the eigenvalues of the system for the selection of Q matrix. This method gives fast tracking of all system state variables for a given perturbation. PSO is used for initial tuning of input control parameters of UPFC. The approach is modular and general enough to include any subsystem with detailed representation. The controller proposed can readily be extended to multi-area system with some augmentation including interface of system dynamics. The simulation result shows improved performance and may be used for better stability and reliability of power system.

Intelligent Multi-Area Power Control: Dynamic Knowledge Domain Inference Concept

This paper presents an intelligent multi-area power control with dynamic knowledge domain inference concept. The ongoing operational shift leads to unacceptable states variation, which may result in power oscillations, and if the controllers are not suitably designed, the system may be interactive and oscillations can aggravate. The study reports a new concept of updating control parameters, which is linked with operational shift, initially in an offline mode in building respective knowledge domain that fits into the framework of changing situations, to ensure states regulation. The proposed concept also provides flexibility to update the knowledge domain over and above offline data with newer dataset combining the nearest data clusters to derive an averaged data (controller parameter) within predefined boundary to change the controller functioning. The knowledge retrieval, as operational shift proceeds, has been mapped utilizing dynamical inference concept. The control so derived, effectively ensures the best damping well within time for the large network reliability and security. The structure of the controller so obtained is termed as the intelligent controller. In the present investigation, parameters of the respective controllers are stored in their respective knowledge domain on the modular basis. Firefly Algorithm (FA) with integral time multiplied by absolute error has been used as the objective function to be minimized. FA is then used to develop knowledge domain structure by way of deriving optimal controller parameters for corresponding operational shift to ensure oscillation damping with minimum settling time as well as overshoot/undershoot. The study is performed on six area sample power system. The proposed concept demonstrates an intelligent control concept for quick oscillation damping as the operating condition changes. Unified power flow controller has been used as an ancillary device as power system stabilizer approaches to the onset of unacceptable response.

ATC enhancement with SSSC-knowledge inference based intelligent controller tuning

The paper presents an analysis of an intelligent controller tuning for transmission line available transfer capability (ATC) enhancement employing coordinated control strategy of power system stabilizers (PSS) and Static synchronous series compensator (SSSC). A concept of Dynamic knowledge inference (DKI) mechanism has been proposed for tuning of PSS and SSSC to damp the inter-area oscillations. The optimal parameters of controllers have been derived from Knowledge domain developed using Gravitational Search Algorithm (GSA) and Firefly Algorithm (FA). In the present paper, SSSC has been used as a supplementary controller to assist PSS functionality when it fails to stabilize at certain operating conditions. A Sample six area system has been considered to demonstrate the effectiveness of the method proposed. The study demonstrates the controlled states response even with the operational shift.

Grid stabilization with PMU signals — A survey

This paper presents critical survey along with the novel concept of smart power flow controller with Phasor Measurement Units (PMUs) signals for stability enhancement of a large power system. Also, the current status of Wide Area Measurement Systems (WAMS) and developments in real time applications of synchrophasor technology in power system has been adequately addressed. It has been noticed that with the help of synchrophasor technology, the system operators are now able to not only monitor and understand the transient/dynamic behaviour of the power system in real time at the control centres but also take quick restoration measures which was not possible in conventional SCADA system. PMUs deployment has shown encouraging results in recent contingencies, by way of assisting system operator with relatively better visualization, for Indian system. Thus, visibility of the network state at milliseconds level has enhanced the security, reliability and stability of the power system. This paper provides understanding of PMUs application and some novel research concept.

Simplifying CORBA Security Service to Support Service Level Access Control

The CORBA Security Service provides a domain based access control model in which interfaces are grouped in domains and a single security policy applies to all the interfaces in the domain. CORBA Security Service does not directly support object and method level access control rules. Grouping interfaces in domains helps in reducing access control rules in a large system with a large number of objects. In an environment where services are provided using methods and similar services are grouped as the methods of an interface, providing service and interface level access control is desirable.