Papers by Saikat Chakrabarti
2015 IEEE Eindhoven PowerTech, 2015
The paper presents a methodology to estimate the rotor angle of a synchronous generator by using ... more The paper presents a methodology to estimate the rotor angle of a synchronous generator by using measurements from phasor measurement units (PMUs). Based on the available measurements, an observer for the damper currents is designed. Using the observed damper currents, known machine parameters, and PMU measurements, stator reactances of the machine are estimated during transients following a disturbance. These updated reactances are then used to find the rotor angle of the generator. Application of the proposed method on a test power system shows promising results.
2014 Eighteenth National Power Systems Conference (NPSC), 2014
Network reduction techniques are useful means of analyzing large, interconnected power systems. T... more Network reduction techniques are useful means of analyzing large, interconnected power systems. The most desirable property of a reduced network is that it should represent the original network as accurately as possible. This paper explores some of the commonly used static network reduction techniques, such as Ward reduction, Kron reduction, Dimo's method, and Zhukov's method. The performances of the reduced networks are evaluated in terms of their ability to follow the bus voltages of the original network, with changes in operating conditions. The IEEE 14bus and 118-bus systems are taken as the test beds.
2016 National Power Systems Conference (NPSC), 2016
In the recent years, the disadvantages of the inverter based distributed energy resource, such as... more In the recent years, the disadvantages of the inverter based distributed energy resource, such as less inertia and lower available kinetic energy as compared to synchronous generator (SG), have been addressed by researchers. As a result, the virtual synchronous generator (VSG) or virtual synchronous machine (VSM) is suggested in literature. VSG controller allows the inverter to mimic the characteristic of the synchronous generator by emulating the swing equation of SG. In case of VSG control, one can change the parameters of swing equation in real-time to improve the transient response of the system, which is not possible in an actual synchronous machine. Based on this concept, an optimized VSG control is discussed in this paper, in which the inertia constant and damping factor are altered between two values based on relative virtual angular velocity and its rate of change. The optimized values of virtual inertia constant and virtual damping factor are obtained, by formulating, aggregated fitness function of frequency deviation and voltage deviation. Particle Swarm Optimization (PSO) technique is used to minimize the function. Lyapunov direct method is used for the transient stability analysis of the system Index Terms-Distributed Energy Resource (DER), droop control, inertia, frequency stability, transient response, Virtual Synchronous Generator (VSG). I.
Faculty of Built Environment and Engineering, 2009
IET Generation, Transmission & Distribution, 2018
Quick fault detection and isolation of faulty section are desired in DC microgrid due to the pres... more Quick fault detection and isolation of faulty section are desired in DC microgrid due to the presence of power electronic converters and low cable impedances. Owing to need of fast disconnection, limited time and data are available for online fault distance estimation. Some of the existing techniques consider source capacitors connected at only one end of the cable; therefore, assume that the fault current is contributed by only one end of the cable. This may not be true in the case of multi-source DC microgrids, where fault current would be supplied from both the ends. Further, existing communication-based techniques require either data synchronisation or fast communication network. To address these issues, this study proposes an online fault location method for multi-source DC microgrid without using communication. The mathematical model of faulted cable section connected to sources at both the ends is derived. This model is used along with the measurements to determine the fault distance. The model consistency with the measurements is quantified using the confidence level based on the residual analysis. A ring-type multi-source DC microgrid system is considered and simulated on real-time digital simulator to demonstrate the effectiveness of the proposed algorithm.
IET Generation, Transmission & Distribution, 2020
With growing connection of distributed energy resources, availability of demand side response tec... more With growing connection of distributed energy resources, availability of demand side response technologies, deployment of smart meters, the distribution system needs advanced network automation for running the system efficiently. State estimation is the core driver of network automation. While the output from SMs will make the state estimation more accurate, advanced metering infrastructures come with several challenges such as noisy, erroneous measurement including lost or missed measurements, exposure to cyber attack and so on. This study proposes a three-phase unbalanced distribution system state estimation which is robust against noisy distribution system measurements, bad data attacks and missing or delayed measurements. This method considers measurement from hybrid sources such as SCADA, micro-phasor measurement units (μPMUs) and SMs. Kalman smoother is used to fill the missing measurements and expectation-maximisation based forecasting is used to interpolate the hybrid measurements to a common timestamp and compensate for the delay in SM measurements. Extensive numerical comparisons are made on IEEE 13, 37 and 123 bus systems to test the robustness of the proposed DSSE against delayed SM measurements and bad or noisy data. An IEEE 24 bus system is modelled and real-time measurement devices are interfaced to it in Hypersim. The data from the hybrid measurement devices of IIT Kanpur smart grid is also used to test the robustness of the proposed method.
IET Generation, Transmission & Distribution, 2018
Quick fault detection and isolation of faulty section are desired in DC microgrid due to the pres... more Quick fault detection and isolation of faulty section are desired in DC microgrid due to the presence of power electronic converters and low cable impedances. Owing to need of fast disconnection, limited time and data are available for online fault distance estimation. Some of the existing techniques consider source capacitors connected at only one end of the cable; therefore, assume that the fault current is contributed by only one end of the cable. This may not be true in the case of multi-source DC microgrids, where fault current would be supplied from both the ends. Further, existing communication-based techniques require either data synchronisation or fast communication network. To address these issues, this study proposes an online fault location method for multi-source DC microgrid without using communication. The mathematical model of faulted cable section connected to sources at both the ends is derived. This model is used along with the measurements to determine the fault distance. The model consistency with the measurements is quantified using the confidence level based on the residual analysis. A ring-type multi-source DC microgrid system is considered and simulated on real-time digital simulator to demonstrate the effectiveness of the proposed algorithm.
IEEE Systems Journal, 2017
Fault recorders can track the transients in the power system during a fault. However, they cannot... more Fault recorders can track the transients in the power system during a fault. However, they cannot provide a wide area picture of the power system operating condition. The provision to track the transients is of great interest for the power system operators. In this paper, a two-stage state estimator, based on both conventional and PMU measurements, is presented. The estimator is able to track the dynamics of the power system states during a fault. The advantage of the proposed state estimator is that it does not require full power system observability by the PMU measurements. The two-stage state estimator was successfully tested on the IEEE 14 and 118 bus systems.
2007 IEEE International Symposium on Intelligent Signal Processing, 2007
Abstract This paper proposes a method for optimal placement of phasor measurement units (PMUs) fo... more Abstract This paper proposes a method for optimal placement of phasor measurement units (PMUs) for measuring the states of a power system. A method to compute the measurement uncertainty associated with the estimated states is also illustrated in the paper. The PMU placement strategy ensures complete observability of the power system states for normal operating conditions, as well as under the loss of a single transmission line or even a single measurement unit. An integer quadratic programming approach is used to minimize the ...
2014 IEEE PES General Meeting | Conference & Exposition, 2014
Monitoring of the power system states in real time, especially after the occurrence of a fault, c... more Monitoring of the power system states in real time, especially after the occurrence of a fault, can enhance the situational awareness of the power system operators. Although the state estimator is designed for monitoring steady state conditions of the power system, the advent of Synchronized Measurement Technology (SMT) can make the state estimator a helpful tool for monitoring the power system operating condition in quasi real time. In this paper, the use of a linear state estimator using only synchronized phasor measurements will be presented. The innovation lies in the use of the linear state estimator for the estimation of the states of the system in the presence of a fault. With the proper PMU placement, all system buses can be monitored accurately and the voltage/angle behavior can be tracked with precision.
2013 IEEE Power & Energy Society General Meeting, 2013
ABSTRACT Network reduction techniques are attractive options for the analysis of large, complex p... more ABSTRACT Network reduction techniques are attractive options for the analysis of large, complex power systems. In the process of network reduction, the original measurements usually get transformed along with the network parameters. It is therefore essential to take into account these transformations in applications such as state estimation. This paper presents a methodology for determining the relation between the measurements in the reduced system and the measurements in the original system. State estimation can then be carried out with the help of the transformed measurements. The developed method is applied on the IEEE 14 bus and IEEE 118 bus test systems.
It has been observed by the practicing engineers that the inclusion of measurements from phasor m... more It has been observed by the practicing engineers that the inclusion of measurements from phasor measurement units (PMUs), current measurements in particular, into the conventional state estimators (SEs), may deteriorate the numerical performance of the SEs in terms of convergence and accuracy. This paper analyzes the reason for such possible illconditioning of the hybrid SEs that use both conventional and PMU measurements. It presents simplified analytical approaches to identify what causes such ill-conditioning when PMU measurements are used. The condition number of SE gain matrix may vary depending on the number of the PMUs and its placement in the network. It has been identified that the large difference in weights that are allocated to the traditional measurements and PMU measurements is the main reason of the ill-conditioning of the hybrid SEs.
2016 National Power Systems Conference (NPSC), 2016
Protection schemes for AC transmission systems are well understood and matured. On the other hand... more Protection schemes for AC transmission systems are well understood and matured. On the other hand, developing proper protection scheme for DC system is still a research challenge. A distributed fault detection and localization scheme, based on local measurements, is proposed in this paper. It is based on the fact that a fault generally leads to a significant drop in the voltage along with its high rate of change. The voltage at the fault point is predicted using a quadratic time varying function. In case of fault, the difference in the predicted and the true values exceeds certain threshold. A systematic procedure for setting the necessary threshold value is also suggested. The protection system has been modelled and tested for different fault types, their locations. and with the noisy measurement. The proposed scheme is validated on a ring type DC microgrid system using Real Time Digital Simulator (RTDS).
2013 IEEE Innovative Smart Grid Technologies-Asia (ISGT Asia), 2013
ABSTRACT One common problem associated with interconnected power systems is that the complete top... more ABSTRACT One common problem associated with interconnected power systems is that the complete topology information and measurement data of the areas are not generally available or difficult to handle in real-time. This paper proposes a methodology to determine in real-time the reduced networks for the systems external to a given area. A sensitivity-based methodology is proposed to identify the nodes to be retained from the external areas. A network reduction methodology is then used to obtain the reduced equivalent for the entire system. A real-time network parameter adjustment algorithm is subsequently used to update the parameters of the reduced network under changes in operating condition. The proposed methods are validated with the help of the modified IEEE 14-bus and IEEE 118-bus systems.
IEEE PES General Meeting, 2010
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Papers by Saikat Chakrabarti