Department of Electrical and Electronics Engineering

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A Comparative Study of Few Conventional and Adaptive Control Algorithms for Manipulator Control.
(DBLP, 2005) Mohan, Sudeept; Bhanot, Surekha
Differential evolution based optimal fuzzy logic control of pH neutralization process
(IEEE, 2014) Bhanot, Surekha; Mohanta, Hare Krishna
Differential evolution (DE) is a member of evolutionary algorithm family which has gained popularity due to its conceptual simplicity and better convergence. This paper presents fuzzy logic based pH control scheme for neutralization process in which DE is used to optimize the input and output membership functions of fuzzy inference system (FIS). The fitness function for optimization is integral of squared errors (ISE). DE is able to converge and find optimal global solution over narrow as well as wide search spaces. Finally the controller performance has been evaluated for servo and regulatory operations.
Enhancing VA sharing between the shunt and series APFs of UPQC with a modified SRF-PAC method
(Wiley, 2020-02) Mathur, Hitesh Datt; Bhanot, Surekha; Patel, Ashish
This study proposes a synchronous reference frame (SRF) theory-based modified power angle control (PAC) method for unified power quality conditioner (UPQC). In the steady state of conventional UPQC, shunt active power filter (APF) supplies total reactive power demand, and series APF sits idle, leading to unbalanced VA loading of the two APFs and increase in overall VA rating of UPQC. PAC methods of UPQC have been devised for reducing the unbalance in VA loading of series and shunt APFs of UPQC by sharing reactive load power between the two APFs. SRF-based PAC methods are robust, but existing ones support only small values of power angle, and thereby limit the improvement in unbalance of VA loading of series and shunt APFs. In this work, a modified SRF-PAC method is proposed to support larger values of power angle, to load the two APFs in proportion to their VA ratings and thus yield smaller unbalance in VA loading of the two APFs of UPQC. Also, a modified power angle estimation is proposed to ensure that voltage and VA load on series converter does not go beyond the rated values. Controller hardware in loop simulations and hardware experiments validate the proposed control method.
Forecast-based modeling and robust frequency control of standalone microgrids considering high penetration of renewable sources
(Wiley, 2020-12) Bhanot, Surekha; Mathur, Hitesh Datt; Mukherjee, Bijoy Krishna
This article proposes forecast-based modeling and robust frequency control strat-egy in isolated microgrids (MGs) to improve its stability. The intermittency andvariability in renewable generation is problem for its smooth integration to MGsconsidering frequency stability. Continuous rise in penetration levels of renew-able energy sources (RESs) is the main motivation behind forecast-based model-ing and controller design for MGs. The disturbances that affect the frequency inthe MG may come from the load side and/or the generation sides. In MGs, atthe generation side, the forecast of power from RESs is usually obtained to get arough estimate of available renewable power. The forecasted power always dif-fers from the actual one, so the secondary frequency controller may get over-burdened due to forecast error resulting in abnormal frequency deviation thatmay lead to unstable power system. The proposedH∞based robust controldesign considers the forecast error which improves the system stability and per-formance against disturbances coming from load/generation side.
Forecasting of solar and wind power using LSTM RNN for load frequency control in isolated microgrid
(Taylor & Francis, 2020) Mathur, Hitesh Datt; Bhanot, Surekha
Renewable sources such as solar PV and wind are stochastic in nature, hence their integration with emerging isolated microgrid (MG) is challenging especially with regards to stability issues. An accurate prediction model of wind and solar sources is necessary to analyze the uncertainty in MG system and to encourage the reliable participation of wind and solar power in the energy market. The advancement in deep learning methods has made it possible to develop a multi-step forecasting model unlike shallow neural networks (SNNs). The time series forecasting using SNN and Recurrent Neural Network (RNN) suffers from the problem of vanishing/exploding gradient while training. To eliminate this problem the long short-term memory (LSTM) RNN has been used in this study for wind speed and solar irradiance prediction. The forecasted solar and wind power is applied to analyze the load frequency behavior and the response of nonrenewable sources for sudden rise and fall in load power demand and PI controller is used to mitigate frequency deviation to ensure the stability of the MG power system.
Frequency regulation in islanded microgrid considering stochastic model of wind and PV
(Wiley, 2019-05) Bhanot, Surekha; Mathur, Hitesh Datt
This paper addresses the method of forecasting the wind and solar power and its application to an islanded microgrid (MG) model for load frequency control. Due to high penetration of renewable energy sources, the islanded MG suffers from lower equivalent inertia. The islanded MG faces several challenges in order to ensure the stable operation by maintaining the frequency and voltage at nominal value. The supply and demand power mismatch is mainly due to continuously changing solar irradiance, fluctuating wind speed, variable inertia, and load fluctuations. The intermittent nature of RESs can significantly affect the system stability; hence, the challenge lies in accurate forecasting of power from the renewable energy sources (RESs) so that a proactive arrangement is made available for compensation of active power or frequency variations. The forecasting will determine the correct estimate of power availability so that the power reserves can be activated prior to large variations in active power affecting the stability of the MGs. To address these challenges, a stochastic model of wind and solar has been developed using “Time series modeling” of the data obtained from Charanka Solar Park under Gujarat Energy Development Agency, India. Wind and solar power availability are forecasted using autoregressive integrated moving average (ARIMA) method including the seasonality factor. The proportional and integral (PI) controller is used for regulating the frequency fluctuations caused due to intermittency in the output of RESs and load power. Various load patterns are applied to the MG model to analyze its load frequency behavior along with variations in secondary sources.
Frequency Stabilization for Multi-area Thermal–Hydro Power System Using Genetic Algorithm-optimized Fuzzy Logic Controller in Deregulated Environment
(Taylor & Francis, 2014-09) Mathur, Hitesh Datt; Bhanot, Surekha
This article develops a model of load frequency control for an interconnected two-area thermal–hydro power system under a deregulated environment. In this article, a fuzzy logic controller is optimized by a genetic algorithm in two steps. The first step of fuzzy logic controller optimization is for variable range optimization, and the second step is for the optimization of scaling and gain parameters. Further, the genetic algorithm-optimized fuzzy logic controller is compared against a conventional proportional-integral-derivative controller and a simple fuzzy logic controller. The proposed genetic algorithm-optimized fuzzy logic controller shows better dynamic response following a step-load change with combination of poolco and bilateral contracts in a deregulated environment. In this article, the effect of the governor dead band is also considered. In addition, performance of genetic algorithm-optimized fuzzy logic controller also has been examined for various step-load changes in different distribution unit demands and compared with the proportional-integral-derivative controller and simple fuzzy logic controller.
Fuzzy Query Processing in Distributed databases
(ICAISC, 2016) Bhanot, Surekha
The problem of evolving databases to make them more intuitive, user-friendly and to be able to answer vague human queries with separate needs for each user has become a popular research topic. The solution to this problem in part has been proposed via databases that aim at inserting fuzzy data into databases hence handling vague human like queries. It has been suggested in many research papers that fuzziness may be applied to databases. However, this approach is infeasible and inefficient for real time processing. In the past 30 years of research, fuzzy databases are still not popular in industry because of unwillingness of companies to replace crisp data with fuzzy data in their databases due to excessive precomputation and possible chances of data inconsistency. Having fuzzy databases also places severe constraints on the database as it will become very difficult to run crisp queries on fuzzy databases. This problem becomes even more complex with the advent of “Big Data”. This paper proposes a three pronged fuzzy logic based technique as a layer of computation above traditional query processing to solve such queries in real time. This fuzzy logic based approach to querying in distributed databases can be used to solve ambiguous queries, incorporating the preferences of each user in the current scenario of excessive data. The results obtained using the fuzzy logic approach are compared with those obtained using traditional approach in terms of accuracy, time taken for each approach and closeness of the results to users requirements.
An improved control method for unified power quality conditioner with unbalanced load
(Elsevier, 2018-09) Mathur, Hitesh Datt; Bhanot, Surekha; Patel, Ashish
This paper proposes an improved control method for Unified Power Quality Conditioner (UPQC) with unbalanced load. In UPQC, shunt APF is overburdened when it alone supplies total load reactive power. PAC method aims at effective utilization of series and shunt APFs by sharing reactive power burden between the two. In presence of unbalanced load, existing PAC methods can lead to circulation of reactive power between two APFs and thereby result in overloading of UPQC. Also, due to unbalanced compensating currents, DC link voltage contains second order oscillations, which deteriorates source current quality. In this work, a new PAC method is proposed, which avoids circulation of reactive power and unnecessary VA burden on UPQC. To suppress DC link voltage oscillations, proposed control employs a ‘mean block’ (moving average) at output of PI controller, which ensures balanced and harmonic free source currents. Also, a ‘percentage unbalance’ parameter has been proposed to quantify the unbalance in three phase quantities. Performance of proposed UPQC system is tested in the presence of non-linear, reactive and unbalanced loads. Dynamic performance of system is studied during grid disturbances such as voltage sag, swell, and change in load. Real time simulation carried out in Opal-RT validate the effectiveness of proposed method. The electrical circuit of UPQC is simulated with sub-microsecond time step on FPGA based computational engine of Opal-RT for better verification of the proposed contro
Improving Performance of UPQC-DG for Compensation of Unbalanced Loads
(IEEE, 2018) Mathur, Hitesh Datt; Bhanot, Surekha
In this paper, an improved Power Angle Control (PAC) method for UPQC-DG has been proposed for effective compensation of unbalanced loads. UPQC-DG provides a simultaneous solution to power quality and renewable integration. PAC methods have been developed for UPQC-DG to enhance VA utilization of series and shunt APFs of UPQC-DG. In case of unbalanced loads, existing PAC methods result in circulation of reactive power and increased VA loading of UPQC-DG. PAC method proposed in this work, is designed to tackle above-mentioned issues. Also, proposed PAC method is based on Synchronous Reference Frame (SRF) theory, which makes it robust to non-ideal voltages. Performance of proposed PAC method has been tested using real time simulation performed in Opal-RT. Simulation results show superior performance of UPQC-DG in presence of unbalanced and non-linear loads using proposed PAC method.
Modeling and frequency control of community micro-grids under stochastic solar and wind sources
(Elsevier, 2020-10) Bhanot, Surekha; Mathur, Hitesh Datt
The Community Micro-Grid (CMG) is a coordinated local grid area served by one or more distribution substations supported by local renewable and other distributed energy resources (DER). In an islanded mode, the CMG stability reduces due to low inertia of the equivalent system and stochastic nature of renewable energy sources (RESs). To study the frequency stability of the islanded CMG system, this paper explores the mathematical modeling aspects of different sources in the CMG and the robust control design for the community microgrid model. The robust design using a fixed structure synthesis method has been presented to compensate for the effect of modeling uncertainty. The uncertainty in the CMG model results in parametric perturbation which degrades its performance and stability. This paper explores the existing mathematical models of CMG’s and different control techniques applied for frequency regulation. Robust controller design for CMG is proposed that can handle the stochastic input disturbances like a sudden change in power coming from solar and wind sources and also the model uncertainty that results in the parametric perturbations. The complete model is simulated using MATLAB Simulink platform and results of frequency deviation obtained by robust and PID controller are compared. The controller hardware in loop (C-HIL) validation of the robust control method for CMG has been done using a real-time controller board (DS1104). This CHIL system also implements the CMG plant-controller model and analyzes the frequency deviation against load and renewable power fluctuations. The oscillations in frequency deviation are analyzed for sudden rise or fall in the renewable power coming from the solar and wind sources. A reduction of 30% is achieved in frequency overshoot and settling time using a robust controller than the PID controller. The controller developed and implemented using synthesis has robust stability and performance for the perturbed CMG model and also shows a better time response, unlike the PID controller.
Modified Deloading Strategy of Wind Turbine Generators for Primary Frequency Regulation in Micro-Grid
(Springer, 2020-04) Bhanot, Surekha; Mathur, Hitesh Datt
In this work, the contribution of wind turbine generator (WTG) to support micro-grid (MG) during depressed frequency condition has been studied with a modified strategy for improving the primary load frequency response of MG. The majority of existing deloading techniques to estimate the reference power are based on the linear relationship. Hence they are not so accurate to mimic the actual speed versus power dynamics of turbine rotor during deloading operation which is inherently nonlinear in nature. In this work, the existing methods have been analyzed in detail with an aim to improve the performance. Based on the analysis a modified deloading method assuming non-linear relation between rotor speed and power of WTG system has been proposed which shows the improved load frequency response in MG. The proposed deloading technique is simulated and validated using real-time digital simulator (OP4510) for the variation in load and generation inside an islanded MG. The results obtained using modified deloading method are compared with existing deloading method and it is found that proposed deloading method handles the non-linearity of the system during deloading operation and also it contributes more power to MG in response to load demand at the cost of slight increase in the speed of turbine rotor.
A new and simple SRF based power angle control for UPQCdg to integrate solar PV into grid
(IEEE, 2017) Mathur, Hitesh Datt; Bhanot, Surekha; Patel, Ashish
In this paper, a new Power Angle Control (PAC) method for Unified Power Quality Conditioner with Distributed Generation (UPQC DG ) is proposed for effective grid integration of solar PV. In UPQC DG shunt Active Power Filter (APF) feeds power from solar PV to load, apart from supplying reactive power demand, leading to increased rating of shunt APF. PAC method aims at effective utilization of series and shunt APFs of UPQC DG to reduce their ratings. In this work a new power angle estimation method based on instantaneous power calculation is proposed. Proposed estimation technique is simple, robust and utilizes already available measurements of UPQC DG . Performance of proposed system is tested in the presence of non-linear and reactive loads with detailed model of solar PV generation system. Dynamic performance of system is studied during grid disturbances such as voltage sag and swell, solar irradiation variation, and change in load. MATLAB/Simulink based simulations validate effectiveness of proposed method.
A new SRF-based power angle control method for UPQC-DG to integrate solar PV into grid
(Wiley, 2018-08) Mathur, Hitesh Datt; Bhanot, Surekha
In this paper, a new synchronous reference frame theory–based power anglecontrol (PAC) method for unified power quality conditioner with distributedgeneration (UPQCDG) is proposed for effective grid integration of solar PV. InUPQCDG, shunt active power filter (APF) feeds power from distributed genera-tor to load, apart from supplying reactive power demand, which leads to increasein VA burden, hence its rating. Power angle control method aims at effective uti-lization of series and shunt APFs through sharing of reactive power to reduceVA burden on shunt APF. Proposed PAC method is based on instantaneousthree-phase power estimation technique, which is simple and robust and utilizesalready available measurements of UPQCDG. Performance of proposed systemis tested in the presence of nonlinear and reactive loads with solar PV genera-tion system. Dynamic performance of system is studied during grid disturbancessuch as voltage sag and swell, solar irradiation variation, and change in load.Effectiveness of proposed method is validated using real-time simulation per-formed in Opal-RT, in which electrical circuit of UPQCDGis simulated on FPGAcomputation engine with submicrosecond time step to emulate real hardwareclosely.
On-line instantaneous and delayed control of a fast tubular reactor
(IEEE, 1998) Bhanot, Surekha
A control system for the tubular reactor-unit has been synthesized, which is a combination of feedforward, feedback and inferential control configurations. The reactor chosen is fast; transient period for a given disturbance varies between 20 and 100 sec, as found from numerical simulation. Therefore a fast on-line control scheme using heuristic approach has been used in which disturbances, manipulated variables and control variables are correlated based on the steady state model of the reactor. Testing of the control scheme has been conducted for both instantaneous as well as delayed control action by numerical simulation.
Optimized adaptive neuro-fuzzy inference system for pH control
(IEEE, 2013) Bhanot, Surekha; Mohanta, Hare Krishna
pH control plays an important role in many modern industrial plants due to strict environment regulations. This paper presents fuzzy logic based pH control scheme for neutralization process in which genetic algorithm is used to optimize the various membership functions of fuzzy inference system. Further, using this optimized fuzzy inference system, adaptive neuro-fuzzy inference system for pH neutralization process is developed. Performances of both control schemes are compared for servo and regulatory operations. Results indicate that adaptive neuro-fuzzy inference system based control uses fewer rules as compared to optimized fuzzy logic based control.
Optimum sizing of PV based UPQC-DG with improved power angle control
(Elsevier, 2020-05) Bhanot, Surekha; Mathur, Hitesh Datt; Patel, Ashish; Yadav, Sisir K.
Unified power quality conditioner with distributed generation (UPQC-DG) is a solution to the problems of power quality and integration of distributed renewable sources. UPQC, being a combination of series and shunt converters, can compensate for most power quality issues, but the use of two power converters increases the cost, and hence optimal sizing methods have been proposed in the literature. Sizing of UPQC-DG components, however, requires special consideration of power injected by DG. This paper proposes an optimum sizing method for UPQC-DG based on an improved power angle control (PAC) technique, which shares reactive power burden between series and shunt converters. Apart from optimal-sizing, this paper incorporates Volt-Ampere (VA) limits in the PAC method to ensure the operation of converters within designed ratings under all conditions. The performance of the proposed power angle control method has been tested for a case study system using Controller Hardware in Loop (CHIL), implemented with Opal-RT and Dspace/micro-labbox, and has been found superior to existing methods.
Process Control: Principles and Applications
(OUP, 2008) Bhanot, Surekha
Process Control—Principles and Applications is specifically designed to serve as a basic text for undergraduate and postgraduate students of instrumentation engineering. It provides a thorough understanding of the basic principles and techniques used in analysis and design of process control
Remote experimentation of “No-load tests on a transformer” in electrical engineering
(IEEE, 2012) Bhanot, Surekha
Currently, rapid developments are taking place to increase the efficiency and outreach of engineering education. Remote-laboratories for remote experimentation is a highly significant and effective development in this area. However, Electrical Engineering experiments are generally difficult to automate due to the risks of high voltages/currents associated with them. In addition digitally controllable electrical machines are expensive and not widely found in many smaller universities. In this paper, remote experimentation of the important experiment “No load tests on a transformer” using PSoC and Labview is presented. More experiments in allied fields can be automated by drawing on this work. In addition it would also serve as an impetus to stronger efforts in this field enabling increased access to high-end laboratories even among the universities with lesser financial capabilities.
Robust Controller Synthesis for Frequency Regulation in Islanded Microgrid
(IEEE, 2017) Mathur, Hitesh Datt; Bhanot, Surekha
Frequency regulation in MG using conventional PID controllers becomes more challenging in the presence of stochastic load and uncertainty in system parameters caused by dynamic perturbation. So, there is a need for a robust controller with acceptable performance and stability for regulating the frequency in MG. The dynamic perturbations include changes in inertia constant and damping coefficient of the power system, which directly affect the frequency of the MG. In this paper, structured H∞ synthesis has been done for robust frequency control in islanded MG. The sources used in MG for compensating the load demand are fuel cell, diesel engine generator and micro-turbine. The robustness and performance of H∞ based controller is validated in the presence of parametric uncertainty and load disturbance caused by stochastic nature of load. The synthesized H∞ based controller is tested for robust stability and performance against ± 50% perturbation of inertia constant and damping coefficient of power system. Simulation results of complete system is also validated with hardware using dSPACE 1104 and control desk