Sukumar Kamalasadan - Academia.edu (original) (raw)

Papers by Sukumar Kamalasadan

2020 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES)

The upsurge in renewable energy generation has led to the modernization of electric power distrib... more The upsurge in renewable energy generation has led to the modernization of electric power distribution systems. Renewable energy sources, such as wind farms are often more reliable but are also prone to power quality problems such as frequency distortion, voltage variations, during grid operations, which occurs during overloading conditions, intermittency, and fault occurrences. This paper presents an approach on how to manage frequency distortions on a grid with a battery integrated windfarm during faults, load dynamics, and renewable energy source intermittency. The proposed supplementary controller is implemented for damping the secondary frequency oscillations on such a wind integrated power grid. Simulation results using the IEEE 13 Bus test feeder show significant advantages when implementing this adaptive control architecture.

2018 IEEE Industry Applications Society Annual Meeting (IAS), 2018

This paper presents a frequency regulation control architecture that can be augmented with existi... more This paper presents a frequency regulation control architecture that can be augmented with existing Wind Turbine Generator (WTG) controllers for maintaining the grid frequency at nominal values on a WTG integrated power grid. The architecture uses an online reduced order modeling of power grid with frequency dependent network equivalents (FDNE) that can seamlessly evaluate the grid fluctuations with respect to the point of common coupling (PCC) of the WTG. Then an adaptive control architecture with the help of an online identification routine is used to augment the torque control of wind generator such that the frequency of the system is balanced. The main advantage of the proposed architecture is that the approach ensures grid frequency stability during oscillations due to grid or WTG related events at any power grid location. The proposed approach not only maintain the frequency within acceptable limits but also makes sure that voltages are at normal values. The architecture is ev...

2016 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), 2016

In this paper a hybrid algorithm that monitors the voltage at the Point of Common Coupling (PCC) ... more In this paper a hybrid algorithm that monitors the voltage at the Point of Common Coupling (PCC) and dispatches the optimal power from battery integrated micro grid is proposed. The proposed architecture integrates a rule based dispatch and a predictive optimization algorithm and ensures optimal power dispatch with minimum voltage variations at the PCC. The methodology and the algorithmic flowchart are discussed first and then the linked systems optimal power dispatch capability is assessed.

This paper presents design and development of a new intelligent controller consisting of three so... more This paper presents design and development of a new intelligent controller consisting of three software agents for the control of parametric and functionally uncertain multi-modal systems. First the development of a stable parallel controller scheme will be discussed. Then, Radial Basis Function Neural Network (RBFNN) based agent design and the adaptive law formulation will be detailed. Further, the design details of a fuzzy multiple model generator and the algorithmic development and the pseudo codes are illustrated. The importance of the proposed control scheme is assessed by applying it for the position control of a single link robotic manipulator. It has been found that the proposed scheme is stable and produced precision tracking of the position trajectory in the presence of parametric and functional uncertainty in manipulator model.

IEEE Transactions on Industry Applications, 2020

This article presents a novel robust adaptive speed control architecture that allows doubly fed i... more This article presents a novel robust adaptive speed control architecture that allows doubly fed induction generator (DFIG) to operate independently of any speed sensors or position encoders. The proposed speed sensorless control based on modified minimum variance adaptive control based speed observer makes the system robust to machine parameter variations and sensor malfunctions. The observer is formulated using a rotor current based reference adaptive system. To ensure robustness to current sensor failure, a modified adaptive rotor side converter control loop is proposed. The online identification for the adaptive control logic is based on the recursive least square estimation technique while the adaptive control law is based on an extended version of the minimum variance control algorithm. To ensure improved dynamic performance for the proposed control, a modification for the terminal voltage control loop is proposed. The reactive power reference for the vector control loop is cal...

2016 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), 2016

This paper presents a system identification based minimum variance architecture for active and re... more This paper presents a system identification based minimum variance architecture for active and reactive power control of a Grid Connected Inverter (GCI). The controller is adaptive as the parameters in the control law are updated online based on identification that relate the output (active and reactive power) and the input (direct and quadrature axis voltage references). The main advantage of the proposed controller is the simplicity in design and its adaptability under varying operating conditions. The paper discusses the design of the controller and presents the simulation results from tests performed using MATLAB SimPowerSystems along with the Hardware-in-the-loop (HIL) implementation. The results show that the proposed controller can be a better alternative to the existing cascaded PI based vector control for grid connected inverters.

2018 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), 2018

Direct Online (DOL) starting inrush current of induction motor creates voltage dip throughout the... more Direct Online (DOL) starting inrush current of induction motor creates voltage dip throughout the distribution network. This is one of the main causes of disruption of nearby sensitive equipment. This paper analyses the characteristics of voltage dip due to the DOL starting induction motor and explores an approach for mitigating the voltage dip using voltage support distributed generation (VSDG). A control strategy to mitigate the motor start transient and to restore the network voltage quickly is proposed. Simulation studies are carried out in order to validate the theoretical framework. It is shown that VSDG can restore the motor starting transient voltage dip quicker than a voltage regulator or an on-load tap changer (OLTC).

This paper presents a novel ramp rate control and active power smoothing methodology for net-load... more This paper presents a novel ramp rate control and active power smoothing methodology for net-load profiles in large power distribution networks where high Photo Voltaic (PV) penetration levels exist. The novelty is to break large systems into virtual local net-load locations where energy storage systems (ESSs) technologies are installed to mitigate severity of the anticipated shape of system net-loads. The proposed methodology uses Fast Fourier signal Transformation (FFT) to generate reference curves that adequately fit ESS active and reactive power capabilities. Then, a least square minimization (LSM) technique is applied taking both ancillary applications into consideration as well as maintaining State of Charge (SoC) within limits for ESS to function efficiently throughout the day. The methodology is applied on a sample aggregated US power distribution system and a 8000 nodes US power grid using CYMEDist simulation platform. Results show significant level of net-load ramp rate re...

2019 IEEE Industry Applications Society Annual Meeting

Transient stability assessment and improvement is critical for power grid operation. It deals wit... more Transient stability assessment and improvement is critical for power grid operation. It deals with the assessment of transient behavior of power grid (especially the generators) when subjected to large disturbances. Clearing a disturbance and taking preventive control actions before it makes the power grid unstable is of crucial importance. In this paper, by using the potential energy of generators, a controller is designed to enhance the transient stability of the system and increase the stability margin. The proposed approach has been tested on IEEE 39 bus test system and the results are provided. It can be seen that the proposed control architecture provide increased stability margin and better controller performance.

IEEE Transactions on Industry Applications

This article presents a novel adaptive control architecture for—connected single-phase inverters ... more This article presents a novel adaptive control architecture for—connected single-phase inverters (SPIs) that can dynamically regulate active and reactive power, thus enabling grid support functions effectively. The base controller framework is that of the active and reactive power control in the dqdqdq-domain. The proposed controller is based on an adaptive minimum variance framework and utilizes an online parametric identifier. The advantage of the proposed scheme is that the architecture can concurrently provide voltage support and line power balancing capability with a performance factor greater than a static proportional-integral (PI) and proportional-resonant (PR) controller. First, the controller capability is evaluated on a proof of concept aggregated power grid model or a single machine infinite bus system. Then, the tests for concurrently providing line balancing and voltage support are conducted by connecting SPIs at several locations on an unbalance three-phase IEEE 123 node distribution system model. It has been demonstrated that the proposed architecture is adaptable and performs better (3% to 5% improvement in error) when compared to static PI and PR controller during varying operating conditions.

IEEE Transactions on Industry Applications

In this article, by calculating the potential energy of generators, a dynamic real-time energy fu... more In this article, by calculating the potential energy of generators, a dynamic real-time energy function based power grid model for the multimachine system is proposed based on available measurement (synchrophasor and prediction). Then, a wide-area optimal control framework that can control multiple generators simultaneously to enhance the transient stability of the system and increase the stability margin is designed and implemented. The main contributions are the proposed dynamic model is dynamic, feasible, and can effectively capture grid dynamics and transients. Furthermore, the architecture provides a dynamic state-space model based on grid events. The proposed approach has been tested on IEEE 68 bus test system and the results are provided. It is observed that the proposed control architecture provides an increased stability margin (up to 60%) and improved critical clearing time by 30%.

2018 IEEE Power & Energy Society General Meeting (PESGM)

Unit Commitment (UC) in its classical form is a mixed integer non-linear programming (MINLP) prob... more Unit Commitment (UC) in its classical form is a mixed integer non-linear programming (MINLP) problem, which is not scalable to power systems with large number of generators. Mixed integer linear programming (MILP) versions of UC use linear or piece-wise linearized cost functions of the generators, which is computationally efficient for larger systems, and is the state-of-the-art method in some of the existing energy management system (EMS) tools. In this paper, we demonstrate that use of linear cost functions in MILP can lead to suboptimal solutions, thus having larger differences in cost which can be possibly run into millions of dollars. We then develop a tighter conic reformulation of the UC problem that retains the quadratic cost functions of the generators and utilizes convex hull descriptions of harder inter-temporal constraints. This improves on the computational efficiency, and as a result, the formulation shows better scalability than MINLP and significantly lower operational costs compared to MILP. We demonstrate efficacy of the proposed UC formulation using several case studies considering upto 1,000 generators.

IET Generation, Transmission & Distribution

Interconnected power grid exhibits oscillatory response after a disturbance in the system. One su... more Interconnected power grid exhibits oscillatory response after a disturbance in the system. One such type of oscillations, the interarea oscillations has the oscillation frequency in the range of 0.1 to 1 Hz. The damping of inter-area oscillations is difficult with local controllers, but it can be achieved using a Wide Area Damping Controller (WADC). For effective control, the input to the WADC should be the most observable signal and the WADC output should be sent to the most controllable generator. This paper presents a measurement-based novel algorithm for multi-input-multi-output (MIMO) transfer function identification of the power system based on optimization to estimate such oscillation frequencies. Based on the MIMO transfer function the optimal control loop for WADC is estimated. The WADC design is based on the discrete linear quadratic regulator (DLQR) and Kalman filtering for damping of inter-area oscillations. Since the MIMO identification is based on actual measurements, the proposed method can accurately monitor changes in the power grid whereas the conventional methods are based on small-signal analysis of a linearized model which does not consider changing operating conditions. The overall algorithm is implemented and validated on a RTDS/RSCAD R and MATLAB R real-time co-simulation platform using two-area and IEEE 39 bus power system models.

IEEE Transactions on Industry Applications

This article presents a frequency regulation and stabilization control architecture for a wind tu... more This article presents a frequency regulation and stabilization control architecture for a wind turbine generator (WTG) integrated power grid, which can be added to existing WTGs. The architecture uses online reduced-order modeling of the power grid with frequency-dependent network equivalent that can seamlessly evaluate the grid fluctuations with respect to the point of common coupling of the wind farm. Then, an adaptive control architecture with the help of an online identification routine is used to balance the torque control of the wind generator (here doubly fed induction generator is considered) such that the frequency of the system is balanced. The main advantage of the proposed architecture is that the approach ensures frequency stability during grid oscillations at any location due to grid-related or WTG-related problems. The proposed approach not only maintains the frequency within acceptable limits during oscillations, but also makes sure that voltages are at normal values. The approach can work without wind speed measurements. The architecture is evaluated using wind-farm-integrated Kundur two-area and IEEE 39-bus test systems using a real-time digital simulator.

IEEE Transactions on Industry Applications

In this paper, a reduced order state observer for doubly fed induction generator (DFIG) is design... more In this paper, a reduced order state observer for doubly fed induction generator (DFIG) is designed that estimate the states just using stator voltage and power measurements. Further, the proposed state observer is used to provide two control strategies for rotor side converter: 1) state estimator based state feedback control; and 2) state estimator based vector control. The state observer and controllers were tested for varying wind conditions using a full-order dynamic model with a real-time simulation platform. First, the proof-of-concept is verified on a grid integrated DFIG considering aggregated grid model represented by an infinite bus. Then, the architecture is validated on a modified IEEE 39-bus system connected with a wind farm. The results confirm that the proposed state observer coupled with existing control for DFIG provides better tracking of the system output without the need for feedback measurements, and at the same time reduces the controller design complexity. Also, these state estimator based controllers eliminate the need of rotor current sensors.

IEEE Transactions on Industry Applications

In this paper, an optimal power dispatch framework for a battery integrated end-user-driven micro... more In this paper, an optimal power dispatch framework for a battery integrated end-user-driven microgrid is proposed that is capable of working in grid-connected and islanded mode. The proposed framework integrates a rule-based dispatch algorithm for the islanded mode that can schedule the battery considering maximum end-user flexibility, with a receding horizon based optimal dispatch algorithm for the grid-connected mode that maximizes grid stability and minimizes grid exchange power to the microgrid. The main advantage of the proposed architecture is that it enables the end-user to operate the microgrid economically (minimizing power from the grid) and at the same time ensures flexibility and grid-level reliability. To demonstrate the applicability and scalability, the proposed architecture is evaluated on a modified IEEE 33 node and IEEE 123 node distribution feeder including three-phase and single-phase connected end-user microgrids suitable for real-time implementation. The test results show that the approach is scalable and the proposed architecture improves feeder reliability and end-user flexibility, keeping overall cost to a minimum.

IEEE Transactions on Industry Applications

This paper presents a system identification based minimum variance control architecture for three... more This paper presents a system identification based minimum variance control architecture for three-phase voltage source inverters that work seamlessly in both grid connected and grid forming modes. The controller is adaptive as parameters in the control law are updated online based on an identified system that relate the inverter output to input. Main advantages of the proposed controller are 1) it can be used in both modes of inverter operation and 2) the controller adapts under varying operating conditions, thus capable of accommodating uncertain energy resources and yet maintaining the power quality. First, the design of the controller is presented and simulation results from test performed using MATLAB SimPowerSystems along with hardware-in-the-loop implementation are illustrated. Second, operation of the inverter controller in the context of micro grids is discussed. The results show that the proposed controller can be a better alternative to the existing cascaded PI based vector control for both grid connected and grid forming modes of operation.

IEEE PES General Meeting, 2010

In this paper, we propose a novel self-evolving multi-agent methodology (MAM) for power system mo... more In this paper, we propose a novel self-evolving multi-agent methodology (MAM) for power system monitoring and protection. The uniqueness of the proposed architecture is the ability of MAM to evolve in the wake of an attack of malicious intent by mutation and thus always monitoring a power system bus remotely. Also, the architecture interacting with the mutated agents uses a

2013 IEEE Energy Conversion Congress and Exposition, 2013

As part of the Renewable Systems Interconnection (RSI), exploring the impact of high levels of PV... more As part of the Renewable Systems Interconnection (RSI), exploring the impact of high levels of PV penetration on standard utility system planning methodologies is critical. In this paper, in order to evaluate the potential impacts on representative distribution feeders for a south-eastern utility that is facing the interconnection of increasing levels of Photovoltaic (PV) generation; detailed steady-state and dynamic modeling and simulation of the integrated systems are performed. The study was conducted on two representative feeders: an almost exclusively residential feeder, and a predominantly rural feeder. Multiple PV penetration levels based on Spring loading were considered: 33.3% and 75% of total feeder loading, and 75% of total connected capacity as extreme case. Steady-state and dynamic analyses were performed. Procedures used to evaluate these impacts and results and observations are discussed. Moreover, possible impact mitigation strategies and evaluation of PV inverter controllers for mitigating the negative impacts are assessed.

2020 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES)

The upsurge in renewable energy generation has led to the modernization of electric power distrib... more The upsurge in renewable energy generation has led to the modernization of electric power distribution systems. Renewable energy sources, such as wind farms are often more reliable but are also prone to power quality problems such as frequency distortion, voltage variations, during grid operations, which occurs during overloading conditions, intermittency, and fault occurrences. This paper presents an approach on how to manage frequency distortions on a grid with a battery integrated windfarm during faults, load dynamics, and renewable energy source intermittency. The proposed supplementary controller is implemented for damping the secondary frequency oscillations on such a wind integrated power grid. Simulation results using the IEEE 13 Bus test feeder show significant advantages when implementing this adaptive control architecture.

2018 IEEE Industry Applications Society Annual Meeting (IAS), 2018

This paper presents a frequency regulation control architecture that can be augmented with existi... more This paper presents a frequency regulation control architecture that can be augmented with existing Wind Turbine Generator (WTG) controllers for maintaining the grid frequency at nominal values on a WTG integrated power grid. The architecture uses an online reduced order modeling of power grid with frequency dependent network equivalents (FDNE) that can seamlessly evaluate the grid fluctuations with respect to the point of common coupling (PCC) of the WTG. Then an adaptive control architecture with the help of an online identification routine is used to augment the torque control of wind generator such that the frequency of the system is balanced. The main advantage of the proposed architecture is that the approach ensures grid frequency stability during oscillations due to grid or WTG related events at any power grid location. The proposed approach not only maintain the frequency within acceptable limits but also makes sure that voltages are at normal values. The architecture is ev...

2016 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), 2016

In this paper a hybrid algorithm that monitors the voltage at the Point of Common Coupling (PCC) ... more In this paper a hybrid algorithm that monitors the voltage at the Point of Common Coupling (PCC) and dispatches the optimal power from battery integrated micro grid is proposed. The proposed architecture integrates a rule based dispatch and a predictive optimization algorithm and ensures optimal power dispatch with minimum voltage variations at the PCC. The methodology and the algorithmic flowchart are discussed first and then the linked systems optimal power dispatch capability is assessed.

This paper presents design and development of a new intelligent controller consisting of three so... more This paper presents design and development of a new intelligent controller consisting of three software agents for the control of parametric and functionally uncertain multi-modal systems. First the development of a stable parallel controller scheme will be discussed. Then, Radial Basis Function Neural Network (RBFNN) based agent design and the adaptive law formulation will be detailed. Further, the design details of a fuzzy multiple model generator and the algorithmic development and the pseudo codes are illustrated. The importance of the proposed control scheme is assessed by applying it for the position control of a single link robotic manipulator. It has been found that the proposed scheme is stable and produced precision tracking of the position trajectory in the presence of parametric and functional uncertainty in manipulator model.

IEEE Transactions on Industry Applications, 2020

This article presents a novel robust adaptive speed control architecture that allows doubly fed i... more This article presents a novel robust adaptive speed control architecture that allows doubly fed induction generator (DFIG) to operate independently of any speed sensors or position encoders. The proposed speed sensorless control based on modified minimum variance adaptive control based speed observer makes the system robust to machine parameter variations and sensor malfunctions. The observer is formulated using a rotor current based reference adaptive system. To ensure robustness to current sensor failure, a modified adaptive rotor side converter control loop is proposed. The online identification for the adaptive control logic is based on the recursive least square estimation technique while the adaptive control law is based on an extended version of the minimum variance control algorithm. To ensure improved dynamic performance for the proposed control, a modification for the terminal voltage control loop is proposed. The reactive power reference for the vector control loop is cal...

2016 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), 2016

This paper presents a system identification based minimum variance architecture for active and re... more This paper presents a system identification based minimum variance architecture for active and reactive power control of a Grid Connected Inverter (GCI). The controller is adaptive as the parameters in the control law are updated online based on identification that relate the output (active and reactive power) and the input (direct and quadrature axis voltage references). The main advantage of the proposed controller is the simplicity in design and its adaptability under varying operating conditions. The paper discusses the design of the controller and presents the simulation results from tests performed using MATLAB SimPowerSystems along with the Hardware-in-the-loop (HIL) implementation. The results show that the proposed controller can be a better alternative to the existing cascaded PI based vector control for grid connected inverters.

2018 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), 2018

Direct Online (DOL) starting inrush current of induction motor creates voltage dip throughout the... more Direct Online (DOL) starting inrush current of induction motor creates voltage dip throughout the distribution network. This is one of the main causes of disruption of nearby sensitive equipment. This paper analyses the characteristics of voltage dip due to the DOL starting induction motor and explores an approach for mitigating the voltage dip using voltage support distributed generation (VSDG). A control strategy to mitigate the motor start transient and to restore the network voltage quickly is proposed. Simulation studies are carried out in order to validate the theoretical framework. It is shown that VSDG can restore the motor starting transient voltage dip quicker than a voltage regulator or an on-load tap changer (OLTC).

This paper presents a novel ramp rate control and active power smoothing methodology for net-load... more This paper presents a novel ramp rate control and active power smoothing methodology for net-load profiles in large power distribution networks where high Photo Voltaic (PV) penetration levels exist. The novelty is to break large systems into virtual local net-load locations where energy storage systems (ESSs) technologies are installed to mitigate severity of the anticipated shape of system net-loads. The proposed methodology uses Fast Fourier signal Transformation (FFT) to generate reference curves that adequately fit ESS active and reactive power capabilities. Then, a least square minimization (LSM) technique is applied taking both ancillary applications into consideration as well as maintaining State of Charge (SoC) within limits for ESS to function efficiently throughout the day. The methodology is applied on a sample aggregated US power distribution system and a 8000 nodes US power grid using CYMEDist simulation platform. Results show significant level of net-load ramp rate re...

2019 IEEE Industry Applications Society Annual Meeting

Transient stability assessment and improvement is critical for power grid operation. It deals wit... more Transient stability assessment and improvement is critical for power grid operation. It deals with the assessment of transient behavior of power grid (especially the generators) when subjected to large disturbances. Clearing a disturbance and taking preventive control actions before it makes the power grid unstable is of crucial importance. In this paper, by using the potential energy of generators, a controller is designed to enhance the transient stability of the system and increase the stability margin. The proposed approach has been tested on IEEE 39 bus test system and the results are provided. It can be seen that the proposed control architecture provide increased stability margin and better controller performance.

IEEE Transactions on Industry Applications

This article presents a novel adaptive control architecture for—connected single-phase inverters ... more This article presents a novel adaptive control architecture for—connected single-phase inverters (SPIs) that can dynamically regulate active and reactive power, thus enabling grid support functions effectively. The base controller framework is that of the active and reactive power control in the dqdqdq-domain. The proposed controller is based on an adaptive minimum variance framework and utilizes an online parametric identifier. The advantage of the proposed scheme is that the architecture can concurrently provide voltage support and line power balancing capability with a performance factor greater than a static proportional-integral (PI) and proportional-resonant (PR) controller. First, the controller capability is evaluated on a proof of concept aggregated power grid model or a single machine infinite bus system. Then, the tests for concurrently providing line balancing and voltage support are conducted by connecting SPIs at several locations on an unbalance three-phase IEEE 123 node distribution system model. It has been demonstrated that the proposed architecture is adaptable and performs better (3% to 5% improvement in error) when compared to static PI and PR controller during varying operating conditions.

IEEE Transactions on Industry Applications

In this article, by calculating the potential energy of generators, a dynamic real-time energy fu... more In this article, by calculating the potential energy of generators, a dynamic real-time energy function based power grid model for the multimachine system is proposed based on available measurement (synchrophasor and prediction). Then, a wide-area optimal control framework that can control multiple generators simultaneously to enhance the transient stability of the system and increase the stability margin is designed and implemented. The main contributions are the proposed dynamic model is dynamic, feasible, and can effectively capture grid dynamics and transients. Furthermore, the architecture provides a dynamic state-space model based on grid events. The proposed approach has been tested on IEEE 68 bus test system and the results are provided. It is observed that the proposed control architecture provides an increased stability margin (up to 60%) and improved critical clearing time by 30%.

2018 IEEE Power & Energy Society General Meeting (PESGM)

Unit Commitment (UC) in its classical form is a mixed integer non-linear programming (MINLP) prob... more Unit Commitment (UC) in its classical form is a mixed integer non-linear programming (MINLP) problem, which is not scalable to power systems with large number of generators. Mixed integer linear programming (MILP) versions of UC use linear or piece-wise linearized cost functions of the generators, which is computationally efficient for larger systems, and is the state-of-the-art method in some of the existing energy management system (EMS) tools. In this paper, we demonstrate that use of linear cost functions in MILP can lead to suboptimal solutions, thus having larger differences in cost which can be possibly run into millions of dollars. We then develop a tighter conic reformulation of the UC problem that retains the quadratic cost functions of the generators and utilizes convex hull descriptions of harder inter-temporal constraints. This improves on the computational efficiency, and as a result, the formulation shows better scalability than MINLP and significantly lower operational costs compared to MILP. We demonstrate efficacy of the proposed UC formulation using several case studies considering upto 1,000 generators.

IET Generation, Transmission & Distribution

Interconnected power grid exhibits oscillatory response after a disturbance in the system. One su... more Interconnected power grid exhibits oscillatory response after a disturbance in the system. One such type of oscillations, the interarea oscillations has the oscillation frequency in the range of 0.1 to 1 Hz. The damping of inter-area oscillations is difficult with local controllers, but it can be achieved using a Wide Area Damping Controller (WADC). For effective control, the input to the WADC should be the most observable signal and the WADC output should be sent to the most controllable generator. This paper presents a measurement-based novel algorithm for multi-input-multi-output (MIMO) transfer function identification of the power system based on optimization to estimate such oscillation frequencies. Based on the MIMO transfer function the optimal control loop for WADC is estimated. The WADC design is based on the discrete linear quadratic regulator (DLQR) and Kalman filtering for damping of inter-area oscillations. Since the MIMO identification is based on actual measurements, the proposed method can accurately monitor changes in the power grid whereas the conventional methods are based on small-signal analysis of a linearized model which does not consider changing operating conditions. The overall algorithm is implemented and validated on a RTDS/RSCAD R and MATLAB R real-time co-simulation platform using two-area and IEEE 39 bus power system models.

IEEE Transactions on Industry Applications

This article presents a frequency regulation and stabilization control architecture for a wind tu... more This article presents a frequency regulation and stabilization control architecture for a wind turbine generator (WTG) integrated power grid, which can be added to existing WTGs. The architecture uses online reduced-order modeling of the power grid with frequency-dependent network equivalent that can seamlessly evaluate the grid fluctuations with respect to the point of common coupling of the wind farm. Then, an adaptive control architecture with the help of an online identification routine is used to balance the torque control of the wind generator (here doubly fed induction generator is considered) such that the frequency of the system is balanced. The main advantage of the proposed architecture is that the approach ensures frequency stability during grid oscillations at any location due to grid-related or WTG-related problems. The proposed approach not only maintains the frequency within acceptable limits during oscillations, but also makes sure that voltages are at normal values. The approach can work without wind speed measurements. The architecture is evaluated using wind-farm-integrated Kundur two-area and IEEE 39-bus test systems using a real-time digital simulator.

IEEE Transactions on Industry Applications

In this paper, a reduced order state observer for doubly fed induction generator (DFIG) is design... more In this paper, a reduced order state observer for doubly fed induction generator (DFIG) is designed that estimate the states just using stator voltage and power measurements. Further, the proposed state observer is used to provide two control strategies for rotor side converter: 1) state estimator based state feedback control; and 2) state estimator based vector control. The state observer and controllers were tested for varying wind conditions using a full-order dynamic model with a real-time simulation platform. First, the proof-of-concept is verified on a grid integrated DFIG considering aggregated grid model represented by an infinite bus. Then, the architecture is validated on a modified IEEE 39-bus system connected with a wind farm. The results confirm that the proposed state observer coupled with existing control for DFIG provides better tracking of the system output without the need for feedback measurements, and at the same time reduces the controller design complexity. Also, these state estimator based controllers eliminate the need of rotor current sensors.

IEEE Transactions on Industry Applications

In this paper, an optimal power dispatch framework for a battery integrated end-user-driven micro... more In this paper, an optimal power dispatch framework for a battery integrated end-user-driven microgrid is proposed that is capable of working in grid-connected and islanded mode. The proposed framework integrates a rule-based dispatch algorithm for the islanded mode that can schedule the battery considering maximum end-user flexibility, with a receding horizon based optimal dispatch algorithm for the grid-connected mode that maximizes grid stability and minimizes grid exchange power to the microgrid. The main advantage of the proposed architecture is that it enables the end-user to operate the microgrid economically (minimizing power from the grid) and at the same time ensures flexibility and grid-level reliability. To demonstrate the applicability and scalability, the proposed architecture is evaluated on a modified IEEE 33 node and IEEE 123 node distribution feeder including three-phase and single-phase connected end-user microgrids suitable for real-time implementation. The test results show that the approach is scalable and the proposed architecture improves feeder reliability and end-user flexibility, keeping overall cost to a minimum.

IEEE Transactions on Industry Applications

This paper presents a system identification based minimum variance control architecture for three... more This paper presents a system identification based minimum variance control architecture for three-phase voltage source inverters that work seamlessly in both grid connected and grid forming modes. The controller is adaptive as parameters in the control law are updated online based on an identified system that relate the inverter output to input. Main advantages of the proposed controller are 1) it can be used in both modes of inverter operation and 2) the controller adapts under varying operating conditions, thus capable of accommodating uncertain energy resources and yet maintaining the power quality. First, the design of the controller is presented and simulation results from test performed using MATLAB SimPowerSystems along with hardware-in-the-loop implementation are illustrated. Second, operation of the inverter controller in the context of micro grids is discussed. The results show that the proposed controller can be a better alternative to the existing cascaded PI based vector control for both grid connected and grid forming modes of operation.

IEEE PES General Meeting, 2010

In this paper, we propose a novel self-evolving multi-agent methodology (MAM) for power system mo... more In this paper, we propose a novel self-evolving multi-agent methodology (MAM) for power system monitoring and protection. The uniqueness of the proposed architecture is the ability of MAM to evolve in the wake of an attack of malicious intent by mutation and thus always monitoring a power system bus remotely. Also, the architecture interacting with the mutated agents uses a

2013 IEEE Energy Conversion Congress and Exposition, 2013

As part of the Renewable Systems Interconnection (RSI), exploring the impact of high levels of PV... more As part of the Renewable Systems Interconnection (RSI), exploring the impact of high levels of PV penetration on standard utility system planning methodologies is critical. In this paper, in order to evaluate the potential impacts on representative distribution feeders for a south-eastern utility that is facing the interconnection of increasing levels of Photovoltaic (PV) generation; detailed steady-state and dynamic modeling and simulation of the integrated systems are performed. The study was conducted on two representative feeders: an almost exclusively residential feeder, and a predominantly rural feeder. Multiple PV penetration levels based on Spring loading were considered: 33.3% and 75% of total feeder loading, and 75% of total connected capacity as extreme case. Steady-state and dynamic analyses were performed. Procedures used to evaluate these impacts and results and observations are discussed. Moreover, possible impact mitigation strategies and evaluation of PV inverter controllers for mitigating the negative impacts are assessed.