T. K. Sunil Kumar

Optimal power flow-based congestion management in restructured power systems

This paper deals with an important issue of transmission network congestion in deregulated power systems, where relieving transmission network congestion without disturbing the existing transactions. The thyristor controlled series capacitor (TCSC) is one of the alternatives to reduce the flow in heavily loaded lines, result in an increased loadability and fulfilled contractual requirement by controlling the power flow in the network. The distribution generation (DG) units are another alternative to compensate deficit power at load bus so that reduce power flow heavily loaded lines. Considerable cost of TCSC and maximum benefits with DG unit at load buses, it is necessary to find their optimal location in the system, a method to determine the optimal placement of these devices has been suggested real power flow and transmission line relief sensitivity index methods. The OPF-based congestion management (CM) strategy has been implemented to minimise production cost and alleviates transmission network congestion with TCSC/DG unit. The OPF-based CM problem is implemented on 26 bus power system network and solutions are obtained by three conventional methods. The experimental results prove that the interior point (IP) method is gives an optimum economical solution.

Congestion management in restructured power systems for smart cities in India

Abstract The development of smart cities in India will require a smart grid for power generation, transmission and distribution systems with a continuous power supply. The transmission line is one of the major elements to supply continuous power to the smart cities via a smart grid. Transmission line congestion is a major technical problem, which must be relieved in order to maintain the system is in a secure state. The present work proposes a combined FACTS device and a microgrid based congestion management (CM) method for relieving transmission line congestion. The optimal placements of the FACTS device and microgrid are obtained by using real power flow (RPF) and transmission line relief (TLR) sensitivity indices. The proposed method has been demonstrated on an IEEE 14 bus test system. The FACTS and MG based CM approached when combined were found to be superior to the performance when the methods are carried out individually.

An evaluation of spatial mapping of indoor environment based on point cloud registration using Kinect sensor

Registration of 3D pointclouds obtained using depth sensor has wide range of applications in robotics. Many different rigid 3D registration algorithms have been proposed in literature, such as Principal Component Analysis, Singular value decomposition, iterative closest point (ICP) and its variants. The ICP is widely used algorithm for registration of point clouds. It is accurate and fast for point cloud registration. In this work, a performance evaluation of point-to-point based ICP algorithm, integration of point-to-point with random sampling and point-to-plane based ICP algorithm by using Microsoft Kinect camera is conducted. Low-cost Microsoft Kinect sensor provides a feasible and economical solution for such point cloud generation. Root mean square error (RMSE) value is taken as the measurement of precision of cloud registration. RMSE value is obtained from the Euclidean distance between corresponding point pairs in both point-clouds, used for the ICP registration. The ICP algorithm always converges monotonically to the nearest local minimum of a mean square distance metric. The results show that the convergence rate is fast during initial iterations.

Novel Two Degree of Freedom Model Matching Controller for Desired Tracking and Disturbance Rejection

A control scheme is proposed in the present paper that introduces Two Degree of Freedom (2-DOF) controller to eliminate the effect of disturbances while tracking the desired trajectory, for Two-Input Two-output (TITO) systems, by implementing an original method that infuses three techniques such as the model order reduction, optimization and the approximate model matching techniques. From authors’ knowledge, first time in literature, the objective of this kind of a proposed method is to accomplish a single low order 2-DOF controller, which can handle desired tracking and disturbance rejection simultaneously, using AGTM/AGMP matching method combined with optimization technique. The desired specifications for achieving the set-point tracking may be encompassed inside what resembles a transfer function matrix. This method is directed at ensuring that the closed loop system is stabilized by implementing a 2-DOF controller while also guaranteeing that it is capable of exhibiting the specified performance standards. This method is cost-effective, computationally simple, easy to implement and can be used for the design without any restriction in the structure/order of the model closed loop transfer function or 2-DOF controller. The efficacy of the proposed methodology is realized when it is performed on coupled tank process.

Novel two degree of freedom model matching controller for set-point tracking in MIMO systems

Abstract A control scheme is proposed in this paper that introduces a two degree of freedom (2-DOF) controller for tracking the desired trajectory of a multi-input multi-output (MIMO) system, by implementing an original method that infuses three techniques, such as the model order reduction, optimization and the approximate model matching techniques. The desired specifications for achieving set-point tracking may be embodied in the form of a transfer function matrix. The proposed method not only ensures the stability of the closed loop system with designed 2-DOF controller, but also satisfies the required performance criteria. This method is cost-effective, computationally simple, easy to implement and can be used in the design without any restrictions in the structure/order of the models closed loop transfer function or 2-DOF controller. Simulation results demonstrate the effectiveness of the developed method.

Design and Implementation of GA Tuned PID Controller for Desired Interaction and Trajectory Tracking of Wheeled Mobile Robot

The paper presents the design and implementation of a PID control based trajectory tracking of a nonholonomic wheeled mobile robot (WMR) with the objective of matching desired time domain specification and specified interaction. The desired time domain specification of output Y(s) is represented as a step response of a second order system with designer specific desired damping ratio (ζ) and natural frequency (ωn). The problem of finding the unknown parameters of PID controllers is formulated in a genetic algorithm (GA) based optimization frame in which the objective is to minimize the difference between the response of the designed closed-loop system and that of the desired closed-loop system. This procedure has been illustrated for achieving the desired time domain specification for WMR, taking different settling time of output response. The interaction analyses are carried out using the concept of Relative Gain Array (RGA). The RGA for both the desired and designed closed-loop systems are found to be matching. It has shown that interaction parameter λ controls both the steady-state and transient response of the desired closed-loop system. The interaction parameter also acts as a parameter which controls the coupling and is chosen by the designer as a specification to be met by the designed closed-loop system with PID controller.

LabVIEW based real time implementation of Fractional Order PID controller for a magnetic levitation system

Fractional Order (FO) PID controller is a generalisation of traditional Integer Order (IO) PID controller using fractional calculus. Compared to IOPID controller, the tuning of FOPID controller is more complex and poses several challenges particularly during real time implementation. In this paper the tuning and design of FOPID controller based on design specifications (phase margin, gain cross over frequency and robustness to variation in the gain) is proposed. The controllers designed in this paper are applied in real time to a Maglev system which is a benchmark system with fast dynamics. The overall control performance, disturbance rejection property and trajectory tracking ability of the system using the proposed controller is validated through experimentation in LabVIEW. Results demonstrate the effectiveness of FOPID controller over the Traditional IO PID controller.

Enhancing fault ride capability in DFIG based wind farm using supplementary rotor controller and dynamic voltage restorer

Fault ride capability in doubly fed induction generators (DFIG) poses three main objectives; (i) the gradual rise of voltage after the fault is cleared in compliance with the grid codes,(ii) limiting rotor inrush current and (iii) limiting DC link overvoltage. This paper proposes a new scheme using dynamic voltage restorer (DVR) and supplementary rotor controller (SRC) to enhance the fault ride through process. DVR which is connected on the stator side and the supplementary rotor controller comes into action only during the fault period. The simulation analysis done in PSCAD/EMTDC shows that the proposed scheme can successfully achieve the fault ride through objectives.

LMP calculation and OPF based congestion management in deregulated power systems

In restructured electricity markets, an effective transmission pricing method is required to address transmission issues and to generate correct economic signals. Transmission line constraints can result in variations in energy prices throughout the network. These prices depend on generator bids, load levels, and transmission network limitations. A congestion charge is incurred when the system is constrained by physical limits. Locational marginal pricing (LMP) has become a popular method in restructured power markets to address the congestion price. This paper presents, LMP calculations at each bus when system working under normal and congested condition, and the congested system has been relieved by optimal placement of TCSC and DG unit. The optimal placement of TCSC and DG unit are suggested by real power flow and transmission line relief (TLR) sensitivity indexes. Optimal power flow based congestion management (OPF based CM) problem is employed to minimize the cost, calculate LMPs and relieve network congestion in the systems. Were the OPF based CM problem solutions have been obtained by Primal Linear Programming (PLP) and Genetic Algorithm (GA), the developed models have been applied for 26 bus power system network. The comparison is made between PLP and GA OPF CM problem solutions, where the solution by the GA method gave better economic results.

Stability of DFIG stator voltage oriented control design based on internal model control

This paper presents the stability investigation of Internal Model Control (IMC) based control design of doubly-fed induction generator (DFIG) in Stator-Voltage-oriented (SVO) synchronous reference frame. The state-space model of DFIG including inner current closed loop dynamics with different feedforward compensation schemes is developed. The inner current loop dynamics is usually ignored when SVO control is employed. The effect of inner current loop dynamics on the damping of critical poles of the system is illustrated through analysis and simulation. The analysis makes it clear that the stability of DFIG in SVO depends mainly on the tuning of the proportionalintegral (PI) controllers. Erroneous tuning results into instability. This paper contributes the tuning methodology of the PI-controllers in order to secure the stability of DFIG under SVO vector control scheme.