||An L-1 Regularized Forecasting-Aided State Estimator For Active Distribution Nerks
||R. Dutta, S. J. Geetha, S. Chakrabarti and Ankush Sharma
||2022 IEEE Transactions on Smart Grid
||With the increased penetration of intermittent distributed energy resources (DERs) and the inclusion of complex loads, the states of an active distribution network (ADN) can experience sudden variations. Most distribution networks are only partially observable using available measuring devices. A distribution system state estimator (DSSE) uses pseudo, i.e., forecasted power injection measurements for the unobserved buses to perform state estimation. The pseudo measurements may fail to capture the sudden change in DERs and loads power. Consequently, the conventional DSSEs may fail to estimate the states when there is a sudden change in the loads and DERs connected to the unobserved buses. This paper proposes a forecasting-aided state estimator for ADNs, which can capture the sudden changes in states caused due to intermittent variations in DERs and loads power. The estimator requires measurements from a limited number of ? PMUs, which are placed according to the depth-of-one unobservability criterion. The present work proposes to split the state vector into two parts. The first part captures the gradual Spatio-temporal variations in the states. The second part captures temporally uncorrelated variations in the states that may occur due to the sudden change in power injections. The proposed estimator tracks both state vector components using an l1-regularization-based estimation model. The algorithm is tested on an unbalanced IEEE benchmark test feeder using real load profiles.
||Microgrid Protection With Penetration Of DERs - A Comprehensive Review
||Jorge I.D. Cisneros-Saldana, Smrutirekha Samal, Hemkesh Singh, Miroslav Begovic, S. R. Samantaray
||2022 Texas Power and Energy Conference (TPEC)
|| Distributed Energy Resources (DER) early uses as a
backup generation has been progressing toward permanent
Distributed Generation (DG), along with the development and
enhancement of new technologies over small-scale generation.
Over last few years, increasing penetration of renewables in the
distribution networks at consumer level raises concerns on
protection, control, stability and reliability. Considering the DG
integration and wide variations in operating conditions of the
microgrid, relays experience protection issues at fault current level
violating important tripping decision rules. This study reviews the
impact of DG penetration as integration means on traditional
overcurrent (OC) protection schemes, being the most common and
widely used relaying scheme in radial distribution networks. This
paper reviews the most representative methods with respect to
various challenges uncovered by exhaustive studies and validations
and reported in the literature. Further, potential adaptive and
intelligent schemes are also discussed for enhancing the
performance over traditional protection schemes in microgrids
||Dual Mode Operation Of A Switched Reluctance Generator-Based Wind Energy Conversion System And A Battery Integrated MG Under Abnormal Utility Grid Condition
||V. Narayanan and B. Singh
||2022 IEEE Power Electronics, Smart Grid and Renewable Energy (PESGRE)
||In this paper, a grid interfaced microgrid (MG) consisting of switched reluctance generator (SRG) based wind energy conversion system (WECS) is presented. The SRG provides an attractive solution for WECS due to its outstanding merits over other conventional generators used in the WECS, such as low cost, rotor free from windings or magnets hence lesser losses, higher efficiency, wide speed operation and no cooling arrangement is required for rotor side. The maximum power from the wind energy is harvested effectively by controlling the asymmetric half-bridge (AHB) SRG converter. Battery storage is provided at the DC bus of the DC-AC power converter to balance the power in the MG. The primary focus is given to the clean wind energy source to meet the load demand. The power generated from the WECS becomes lower/excess than demand, then deficient power is met from the utility grid, or the excess power is injected into the utility grid to balance the power within the MG. Whenever the utility grid fails, then the MG operates in off-grid mode, where the power output from the WECS and the battery storage balances the power within the MG. Moreover, once the grid failure is resolved, the MG is automatically shifted to on-grid mode without causing any disturbances in the MG. An improved second-order generalized integrator-frequency locked loop (ISOGI-FLL) filter is developed to estimate the positive sequence components (PSCs) of the utility grid voltages to enhance grid power quality even under abnormal grid conditions. Moreover, it calculates the load currents' active weight fundamental components for enhancing the quality of various power quality (PQ) indices at the utility grid.
||Power Management Of Hybrid Storage Using Rule-Based Adaptive Filtering In Electric Vehicle
||Abhishek Panda, Mahesh K. Mishra
||2022 IEEE Power Electronics, Smart Grid and Renewable Energy (PESGRE)
|| In an Electric Vehicle (EV) application, hybrid sources, including battery and supercapacitor, use a low pass filter to reduce the fluctuating power absorbed by the battery. The degree of fluctuating power distribution depends on the time constant of the low pass filter. This paper proposes a method to find the time constant value depending on the rate of change of battery current. Although the time constant is known from the design method of the low pass filter, the filtering technique will not maintain the state of charge of the supercapacitor (SOC sc ) within the limits. In order to resolve this issue, rule-based adaptive filtering is proposed in this paper. This algorithm eliminates the disadvantage of the conventional filter-based method of energy management in terms of battery power loss and (SOC sc ) regulation. The feasibility of the proposed method is validated through MATLAB/SIMULINK.
||An Integrated Control Of Enhanced-PLL And Synchronverter For Unbalanced Grid
||Hariharan R and Mahesh K. Mishra
||2022 IEEE Transactions on Industry Applications
||Synchronverter (SV) control is a popular control for distributed energy resources (DERs), as it has the capability of synchronous generator (SG) behavior emulation. However, additional control along with a higher order phase-locked loop (PLL) must be integrated into SV control, for ripple-free power injection into an unbalanced grid. Thus, the enhanced-PLL (EPLL) structure comprising positive, negative, and zero sequence core units, is integrated into standard SV control in the proposed control, which is capable of ripple-free power injection by DER into an unbalanced grid. Further, the proposed integrated control is also capable of successfully achieving pre-synchronization i.e., synchronization of DER voltage to the grid voltage, before connection of DER to the grid. Other important benefits of proposed control over existing VSG methods for unbalanced grid conditions are a reduced number of parameters designed due to the simple modular control structure and usage of the inherent low pass filter of SV in the positive sequence core unit. Simulation results demonstrating successful pre-synchronization and ripple-free power injection by DER into an unbalanced grid are presented in this work.
||An Enhanced Differential Protection Scheme For LVDC Microgrid
||Abha Saxena, Nikhil Kumar Sharma, S R Samantaray
||2022 IEEE Journal of Emerging and Selected Topics in Power Electronics
||The low-voltage dc (LVDC) microgrid possesses numerous benefits and their penetration in the power system has increased rapidly in recent years. However, the detection of faults in the LVDC microgrid is a challenging issue due to the large magnitude of fault currents and fault-level variation in the microgrid. The performance of the recent current and its derivative-based protection scheme is limited in case of faults in the islanding mode of operation, different microgrid topologies, varying distributed generations (DGs) penetration, and against the measurement noise. This article presents an enhanced differential protection scheme for LVDC microgrid integrated with multiple DGs and storage. The differential current and its first derivative are processed through the decision tree (DT) algorithm for fault detection and the K-nearest neighbor (KNN) technique is utilized for fault classification. The robustness of the proposed protection scheme is tested for different fault types and fault conditions with variation in microgrid topology and operating conditions. The impact of the intermittent and volatile nature of the DGs, the presence of measurement noise, and assessment during external faults and critical no-fault cases have been investigated. The proposed scheme is tested on the MATLAB/ SIMULINK and validated on the Typhoon HIL platform for the assessment of real-time performance. The test results show that the proposed scheme can detect and classify faults with high accuracy and faster response time and, thus, can be a potential candidate for providing dependable protection measures for LVDC microgrids.
||New Perspectives On Stability Of Decoupled Double Synchronous Reference Frame PLL
||P. D. Achlerkar and B. K. Panigrahi
||2022 IEEE Transactions on Power Electronics
||Modeling and interpretation of synchronization stability of energy conversion systems with the unbalanced grid is a very practical, complicated, and less explored topic. This article demonstrates an inherent instability phenomenon in the synchronous reference frame phase locked-loop (SRF-PLL). The need for the small-signal model improvement and Floquet-stability-theory-based analysis is thereby demonstrated. Furthermore, decoupled double synchronous reference frame (DDSRF) PLL, which is a benchmark tool for unbalanced grid synchronization, is investigated for its behavior upon small disturbances. A precise sixth-order small-signal linear time-periodic model of DDSRF-PLL is obtained considering parameters of the input signal as well as of PLL. Floquet-theory-based stability and modal analysis are carried out to gain insights into dynamic properties of DDSRF-PLL. Impacts of distortions in grid voltage such as unbalance, harmonics, jumps in amplitude, phase, and frequency are analyzed for both performance and stability. This article is useful for the design and exact analysis of unbalanced grid interfaced converter systems and system interaction studies.
||Emergence Of Distribution System Operator In The Indian Power Sector And Possible Way Ahead
||A. M. Jadhav and Abhijit R. Abhyankar
||2022 Energy Policy, Elsevier
||The rapid integration of renewable energy sources and demand-side participation has changed how electrical energy is being purchased, transmitted, distributed, or even consumed. It has opened new opportunities for the Indian power sector to redefine its existing operational and business models to cope with the unique challenges and follow an approach that maximizes social welfare across all energy supply chain segments. This journey will have significant impacts on the Distribution companies (DISCOMs). The anticipated segregation of wire and supply business would bring more operational efficiency in the distribution sector. The subsequent entry of retailers will handle the supply business of electricity. A new entity is likely to emerge as Distribution System Operator (DSO), providing network access, grid services and enabling consumer market participation. The emergence of DSO is decisive in achieving better socioeconomic and environmental benefits. The idea of DSO is still at the conceptual level in India. In this paper, an attempt has been made to present the DSO definition, highlight its need, enlist various DSO functions, and suggest possible DSO creation options. DSO's few competitive market models are examined from the Indian perspective, which will engage all stakeholders actively and ensure the reliable and efficient operation of the overall Indian power grid.
||Topology Tracking For Active Distribution Networks
||R. Dutta, S. Chakrabarti and Ankush Sharma
||2021 IEEE Transactions on Power Systems
||With the integration of intermittent renewable energy sources in the distribution network, the number of network reconfiguration events has increased significantly. In a medium voltage distribution network, most of the critical circuit breakers' (CBs') statuses are monitored by remote terminal units (RTUs). However, in many cases, some of the CBs' status may not be correctly updated by the supervisory control and data acquisition (SCADA) system because of communication failure and data packet loss issues. Thus, the distribution system operator (DSO) cannot solely rely on CB status provided by the SCADA for topology detection. This paper proposes a data-driven topology tracking algorithm for active distribution networks. The topology of the distribution network is represented with a time-varying connectivity matrix. The changes in network topology are detected by estimating the elements of the bus connectivity matrix using voltage phase angle measurements provided by a sparse set of micro phasor measurement units (?PMUs). The algorithm extracts information from previous network topology using an l 1 norm regularization on the difference of consecutive connectivity matrices. The changes in topology can be detected by observing a few ?PMU phasor samples. The algorithm is tested on IEEE benchmark test feeders with real load profiles.
||Risk Constrained Energy Efficient Optimal Operation Of A Converter Governed AC/DC Hybrid Distribution Network With Distributed Energy Resources And Volt-VAR Controlling Devices
||S. Paul, Ankush Sharma and N. P. Padhy
||2020 IEEE Transactions on Power Systems
||Increasing penetration of direct current (dc) based distributed energy resources and dc loads in the conventional alternating current (ac) network necessitate the deployment of ac/dc hybrid distribution networks (HDNs). In view with the development of advanced energy management policy for ac/dc HDNs, unlike previous literatures, this article proposes a risk constrained energy efficient management algorithm by merging load shifting (LS) and conservation voltage reduction (CVR) techniques. The optimization framework aims to simultaneously minimize both true and conditional risk or conditional value at risk values of the expected energy cost under uncertain solar power generation, load demand, and upper grid energy price. In contrast with the available stochastic optimization process, in this article, two-point estimation strategy is employed in place of Monte Carlo simulation for scenario generation from the probability density functions of the uncertain parameters to reduce computational exertion. The proposed centralized optimization framework is initially developed as mixed integer nonconvex programming but to avoid computation complexity, the nonlinear components are replaced by their linear counterparts. Later, a new solution process named successive mixed integer linear programming (s-MILP) is proposed to obtain the optimal decisions for deployment of LS and CVR through smart inverters and volt-VAR controlling devices. Efficacy of the proposed technique is demonstrated on modified IEEE 33 bus ac/dc HDN and the most energy efficient operation is found by merging LS and CVR. Simulation outcomes prove fast and near optimal convergence of the s-MILP compared to conventional second-order conic programming relaxed mixed integer convex programming and piecewise linearization based MILP. Further, to assess the impact of network size on the solution time and optimality, the proposed advanced distribution network management systems strategy is employed on 132 bus ac/dc HD...