This page has only limited features, please log in for full access.
Recent developments in the renewable energy sector have seen an unprecedented growth in residential photovoltaic (PV) installations. However, high PV penetration levels often lead to overvoltage problems in low-voltage (LV) distribution feeders. Smart inverter control such as active power curtailment (APC)-based overvoltage control can be implemented to overcome these challenges. The APC technique utilizes a constant droop-based approach which curtails power rigidly, which can lead to significant energy curtailment in the LV distribution feeders. In this paper, different variations of the APC technique with linear, quadratic, and exponential droops have been analyzed from the point-of-view of energy curtailment for a LV distribution network in North America. Further, a combinatorial approach using various droop-based APC methods in conjunction with adaptive dynamic programming (ADP) as a supplementary control scheme has also been proposed. The proposed approach minimizes energy curtailment in the LV distribution network by adjusting the droop gains. Simulation results depict that ADP in conjunction with exponential droop reduces the energy curtailment to approximately 50% compared to using the standard linear droop.
Manisha Maharjan; Ujjwol Tamrakar; Zhen Ni; Bishnu Bhattarai; Reinaldo Tonkoski. Overvoltage Prevention and Curtailment Reduction Using Adaptive Droop-Based Supplementary Control in Smart Inverters. Applied Sciences 2021, 11, 7900 .
AMA StyleManisha Maharjan, Ujjwol Tamrakar, Zhen Ni, Bishnu Bhattarai, Reinaldo Tonkoski. Overvoltage Prevention and Curtailment Reduction Using Adaptive Droop-Based Supplementary Control in Smart Inverters. Applied Sciences. 2021; 11 (17):7900.
Chicago/Turabian StyleManisha Maharjan; Ujjwol Tamrakar; Zhen Ni; Bishnu Bhattarai; Reinaldo Tonkoski. 2021. "Overvoltage Prevention and Curtailment Reduction Using Adaptive Droop-Based Supplementary Control in Smart Inverters." Applied Sciences 11, no. 17: 7900.
The displacement of rotational generation and the consequent reduction in system inertia is expected to have major stability and reliability impacts on modern power systems. Fast-frequency support strategies using energy storage systems (ESSs) can be deployed to maintain the inertial response of the system, but information regarding the inertial response of the system is critical for the effective implementation of such control strategies. In this paper, a moving horizon estimation (MHE)-based approach for online estimation of inertia constant of low inertia microgrids is presented. Based on the frequency measurements obtained in response to a non-intrusive excitation signal from an ESS, the inertia constant was estimated using local measurements from the ESS’s phase-locked loop. The proposed MHE formulation was first tested in a linearized power system model, followed by tests in a modified microgrid benchmark from Cordova, Alaska. Even under moderate measurement noise, the technique was able to estimate the inertia constant of the system well within ±20% of the true value. Estimates provided by the proposed method could be utilized for applications such as fast-frequency support, adaptive protection schemes, and planning and procurement of spinning reserves.
Ujjwol Tamrakar; David A. Copp; Tu A. Nguyen; Timothy M. Hansen; Reinaldo Tonkoski. Real-Time Estimation of Microgrid Inertia and Damping Constant. IEEE Access 2021, 9, 114523 -114534.
AMA StyleUjjwol Tamrakar, David A. Copp, Tu A. Nguyen, Timothy M. Hansen, Reinaldo Tonkoski. Real-Time Estimation of Microgrid Inertia and Damping Constant. IEEE Access. 2021; 9 ():114523-114534.
Chicago/Turabian StyleUjjwol Tamrakar; David A. Copp; Tu A. Nguyen; Timothy M. Hansen; Reinaldo Tonkoski. 2021. "Real-Time Estimation of Microgrid Inertia and Damping Constant." IEEE Access 9, no. : 114523-114534.
Converter-based generators are increasingly replacing classical synchronous generation, resulting in significant challenges to the operation and planning of modern power systems. Power electronics (PE)-based equipment, along with non-linear PE-driven loads, introduce time-varying characteristics and fast switching behavior that increases the complexity of the power system model. Faster control actions are needed to overcome the fast switching dynamics to ensure the reliability and stability of future power systems. Thus, this requires advanced and detailed simulation methods and tools with highly accurate equivalent models to embody the relatively slower electromechanical to faster electromagnetic transient (EMT) phenomena. Conventional transient stability analysis using positive-sequence simulators has become inadequate for representing converter-dominated power systems, while EMT simulators suffer from the high computational burden. This review paper presents accelerated EMT simulation methods and tools that are categorized and discussed in three topics: system equivalents, simulation methods, and accelerating tools. Dynamic system equivalent techniques are discussed to model small to large interconnected external systems of the grid network. Moreover, a systematic review is made for existing EMT simulation methods, along with advanced co-simulation methods, for addressing simulation speed and accuracy issues in large power system networks. Emerging hardware-based simulation tools are reviewed that reduce the computational burden and increase the simulation efficiency of the power system model. Challenges and trends in EMT simulation are also presented and concluded by providing perspectives on this research topic.
Sunil Subedi; Manisha Rauniyar; Saima Ishaq; Timothy M. Hansen; Reinaldo Tonkoski; Mariko Shirazi; Richard Wies; Phylicia Cicilio. Review of Methods to Accelerate Electromagnetic Transient Simulation of Power Systems. IEEE Access 2021, 9, 1 -1.
AMA StyleSunil Subedi, Manisha Rauniyar, Saima Ishaq, Timothy M. Hansen, Reinaldo Tonkoski, Mariko Shirazi, Richard Wies, Phylicia Cicilio. Review of Methods to Accelerate Electromagnetic Transient Simulation of Power Systems. IEEE Access. 2021; 9 ():1-1.
Chicago/Turabian StyleSunil Subedi; Manisha Rauniyar; Saima Ishaq; Timothy M. Hansen; Reinaldo Tonkoski; Mariko Shirazi; Richard Wies; Phylicia Cicilio. 2021. "Review of Methods to Accelerate Electromagnetic Transient Simulation of Power Systems." IEEE Access 9, no. : 1-1.
In response to national and international carbon reduction goals, renewable energy resources like photovoltaics (PV) and wind, and energy storage technologies like fuel-cells are being extensively integrated in electric grids. All these energy resources require power electronic converters (PECs) to interconnect to the electric grid. These PECs have different response characteristics to dynamic stability issues compared to conventional synchronous generators. As a result, the demand for validated models to study and control these stability issues of PECs has increased drastically. This paper provides a review of the existing PEC model types and their applicable uses. The paper provides a description of the suitable model types based on the relevant dynamic stability issues. Challenges and benefits of using the appropriate PEC model type for studying each type of stability issue are also presented.
Chinmay Shah; Jesus D. Vasquez-Plaza; Daniel D. Campo-Ossa; Juan F. Patarroyo-Montenegro; Nischal Guruwacharya; Niranjan Bhujel; Rodrigo D. Trevizan; Fabio Andrade Rengifo; Mariko Shirazi; Reinaldo Tonkoski; Richard Wies; Timothy M. Hansen; Phylicia Cicilio. Review of Dynamic and Transient Modeling of Power Electronic Converters for Converter Dominated Power Systems. IEEE Access 2021, 9, 82094 -82117.
AMA StyleChinmay Shah, Jesus D. Vasquez-Plaza, Daniel D. Campo-Ossa, Juan F. Patarroyo-Montenegro, Nischal Guruwacharya, Niranjan Bhujel, Rodrigo D. Trevizan, Fabio Andrade Rengifo, Mariko Shirazi, Reinaldo Tonkoski, Richard Wies, Timothy M. Hansen, Phylicia Cicilio. Review of Dynamic and Transient Modeling of Power Electronic Converters for Converter Dominated Power Systems. IEEE Access. 2021; 9 ():82094-82117.
Chicago/Turabian StyleChinmay Shah; Jesus D. Vasquez-Plaza; Daniel D. Campo-Ossa; Juan F. Patarroyo-Montenegro; Nischal Guruwacharya; Niranjan Bhujel; Rodrigo D. Trevizan; Fabio Andrade Rengifo; Mariko Shirazi; Reinaldo Tonkoski; Richard Wies; Timothy M. Hansen; Phylicia Cicilio. 2021. "Review of Dynamic and Transient Modeling of Power Electronic Converters for Converter Dominated Power Systems." IEEE Access 9, no. : 82094-82117.
The lack of inertial response from non-synchronous, inverter-based generation in microgrids makes the power system vulnerable to a large rate of change of frequency (ROCOF) and frequency excursions. Energy storage systems (ESSs) can be utilized to provide fast-frequency support to prevent such large excursions in the system. However, fast-frequency support is a power-intensive application that has a significant impact on the ESS lifetime. In this paper, a framework that allows the ESS operator to provide fast-frequency support as a service is proposed. The framework maintains the desired quality-of-service (limiting the ROCOF and frequency) while taking into account the ESS lifetime and physical limits. The framework utilizes moving horizon estimation (MHE) to estimate the frequency deviation and ROCOF from noisy phase-locked loop (PLL) measurements. These estimates are employed by a model predictive control (MPC) algorithm that computes control actions by solving a finite-horizon, online optimization problem. Additionally, this approach avoids oscillatory behavior induced by delays that are common when using low-pass filters as with traditional derivative-based (virtual inertia) controllers. MATLAB/Simulink simulations on a test system from Cordova, Alaska, show the effectiveness of the MHE-MPC approach to reduce frequency deviations and ROCOF of a low-inertia microgrid.
Ujjwol Tamrakar; David A. Copp; Tu Anh Nguyen; Timothy M. Hansen; Reinaldo Tonkoski. Optimization-Based Fast-Frequency Estimation and Control of Low-Inertia Microgrids. IEEE Transactions on Energy Conversion 2020, 36, 1459 -1468.
AMA StyleUjjwol Tamrakar, David A. Copp, Tu Anh Nguyen, Timothy M. Hansen, Reinaldo Tonkoski. Optimization-Based Fast-Frequency Estimation and Control of Low-Inertia Microgrids. IEEE Transactions on Energy Conversion. 2020; 36 (2):1459-1468.
Chicago/Turabian StyleUjjwol Tamrakar; David A. Copp; Tu Anh Nguyen; Timothy M. Hansen; Reinaldo Tonkoski. 2020. "Optimization-Based Fast-Frequency Estimation and Control of Low-Inertia Microgrids." IEEE Transactions on Energy Conversion 36, no. 2: 1459-1468.
This paper introduces the concept of the operating region of a virtual synchronous generator (VSG). The main objective of the operating region is to help take a decision on choosing proper VSG parameters. A VSG based on a diesel generator (Genset) model was used as the study case. The theoretical analysis examined the impact of relevant genset-based VSG parameters, such as droop factor, mdr, inertia, J, and damping, D, on the output electrical frequency. The main result of this analysis showed that it is possible to define inertia-damping surfaces which are parameterized upon different values of the droop factor. The operating region of the VSG is then defined as the locus of the triples (mdr; J; D) where the frequency transient response satisfies certain specifications in terms of peak frequency, peak time and rate of change. Experimental results showed that the VSG achieved a satisfactory performance for different values of speed droop during a transient and also in steady-state, validating the model of the genset. In comparison with simulation results, the measured peak frequencies deviated with a mean absolute error of 0.2% and the steady-state frequencies with a mean absolute error of 0.12 %, validating the concept of the operating region.
Miguel A. Torres; Reinaldo Tonkoski; Carlos R. Baier. Operating Region of a Genset-Based Virtual Synchronous Generator. IEEE Access 2020, 8, 136382 -136392.
AMA StyleMiguel A. Torres, Reinaldo Tonkoski, Carlos R. Baier. Operating Region of a Genset-Based Virtual Synchronous Generator. IEEE Access. 2020; 8 (99):136382-136392.
Chicago/Turabian StyleMiguel A. Torres; Reinaldo Tonkoski; Carlos R. Baier. 2020. "Operating Region of a Genset-Based Virtual Synchronous Generator." IEEE Access 8, no. 99: 136382-136392.
This document is a summary of a report prepared by the IEEE PES Task Force (TF) on Microgrid Stability Definitions, Analysis, and Modeling \cite{task}, which defines concepts and identifies relevant issues related to stability in microgrids. In this paper, definitions and classification of microgrid stability are presented and discussed, considering pertinent microgrid features such as voltage-frequency dependency, unbalancing, low inertia, and generation intermittency. A few examples are also presented, highlighting some of the stability classes defined in the paper. Further examples, along with discussions on microgrid components modeling and stability analysis tools can be found in the TF report.
Mostafa Farrokhabadi; Claudio A. Canizares; John William Simpson-Porco; Ehsan Nasr; Lingling Fan; Patricio A. Mendoza-Araya; Reinaldo Tonkoski; Ujjwol Tamrakar; Nikos D. Hatziargyriou; Dimitris Lagos; Richard W. Wies; Mario Paolone; Marco Liserre; Lasantha Meegahapola; Mahmoud Kabalan; Amir H. Hajimiragha; Dario Peralta; Marcelo A. Elizondo; Kevin Paul Schneider; Francis K. Tuffner; James T. Reilly. Microgrid Stability Definitions, Analysis, and Examples. IEEE Transactions on Power Systems 2019, 35, 13 -29.
AMA StyleMostafa Farrokhabadi, Claudio A. Canizares, John William Simpson-Porco, Ehsan Nasr, Lingling Fan, Patricio A. Mendoza-Araya, Reinaldo Tonkoski, Ujjwol Tamrakar, Nikos D. Hatziargyriou, Dimitris Lagos, Richard W. Wies, Mario Paolone, Marco Liserre, Lasantha Meegahapola, Mahmoud Kabalan, Amir H. Hajimiragha, Dario Peralta, Marcelo A. Elizondo, Kevin Paul Schneider, Francis K. Tuffner, James T. Reilly. Microgrid Stability Definitions, Analysis, and Examples. IEEE Transactions on Power Systems. 2019; 35 (1):13-29.
Chicago/Turabian StyleMostafa Farrokhabadi; Claudio A. Canizares; John William Simpson-Porco; Ehsan Nasr; Lingling Fan; Patricio A. Mendoza-Araya; Reinaldo Tonkoski; Ujjwol Tamrakar; Nikos D. Hatziargyriou; Dimitris Lagos; Richard W. Wies; Mario Paolone; Marco Liserre; Lasantha Meegahapola; Mahmoud Kabalan; Amir H. Hajimiragha; Dario Peralta; Marcelo A. Elizondo; Kevin Paul Schneider; Francis K. Tuffner; James T. Reilly. 2019. "Microgrid Stability Definitions, Analysis, and Examples." IEEE Transactions on Power Systems 35, no. 1: 13-29.
Big data has potential to unlock novel groundbreaking opportunities in power grid that enhances a multitude of technical, social, and economic gains. As power grid technologies evolve in conjunction with measurement and communication technologies, this results in unprecedented amount of heterogeneous big data. In particular, computational complexity, data security, and operational integration of big data into power system planning and operational frameworks are the key challenges to transform the heterogeneous large dataset into actionable outcomes. In this context, suitable big data analytics combined with visualization can lead to better situational awareness and predictive decisions. This paper presents a comprehensive state-of-the-art review of big data analytics and its applications in power grids, and also identifies challenges and opportunities from utility, industry, and research perspectives. The paper analyzes research gaps and presents insights on future research directions to integrate big data analytics into power system planning and operational frameworks. Detailed information for utilities looking to apply big data analytics and insights on how utilities can enhance revenue streams and bring disruptive innovation are discussed. General guidelines for utilities to make the right investment in the adoption of big data analytics by unveiling interdependencies among critical infrastructures and operations are also provided.
Bishnu P. Bhattarai; Sumit Paudyal; Yusheng Luo; Manish Mohanpurkar; Kwok Cheung; Reinaldo Tonkoski; Rob Hovsapian; Kurt S. Myers; Rui Zhang; Power Zhao; Milos Manic; Song Zhang; Xiaping Zhang. Big data analytics in smart grids: state‐of‐the‐art, challenges, opportunities, and future directions. IET Smart Grid 2019, 2, 141 -154.
AMA StyleBishnu P. Bhattarai, Sumit Paudyal, Yusheng Luo, Manish Mohanpurkar, Kwok Cheung, Reinaldo Tonkoski, Rob Hovsapian, Kurt S. Myers, Rui Zhang, Power Zhao, Milos Manic, Song Zhang, Xiaping Zhang. Big data analytics in smart grids: state‐of‐the‐art, challenges, opportunities, and future directions. IET Smart Grid. 2019; 2 (2):141-154.
Chicago/Turabian StyleBishnu P. Bhattarai; Sumit Paudyal; Yusheng Luo; Manish Mohanpurkar; Kwok Cheung; Reinaldo Tonkoski; Rob Hovsapian; Kurt S. Myers; Rui Zhang; Power Zhao; Milos Manic; Song Zhang; Xiaping Zhang. 2019. "Big data analytics in smart grids: state‐of‐the‐art, challenges, opportunities, and future directions." IET Smart Grid 2, no. 2: 141-154.
HongBin Sun; Qinglai Guo; Junjian Qi; Venkataramana Ajjarapu; Richard Bravo; Joe Chow; Zhengshuo Li; Rohit Moghe; Ehsan Nasr-Azadani; Ujjwol Tamrakar; Glauco N. Taranto; Reinaldo Tonkoski; Gustavo Valverde; Qiuwei Wu; Guangya Yang. Review of Challenges and Research Opportunities for Voltage Control in Smart Grids. IEEE Transactions on Power Systems 2019, 34, 2790 -2801.
AMA StyleHongBin Sun, Qinglai Guo, Junjian Qi, Venkataramana Ajjarapu, Richard Bravo, Joe Chow, Zhengshuo Li, Rohit Moghe, Ehsan Nasr-Azadani, Ujjwol Tamrakar, Glauco N. Taranto, Reinaldo Tonkoski, Gustavo Valverde, Qiuwei Wu, Guangya Yang. Review of Challenges and Research Opportunities for Voltage Control in Smart Grids. IEEE Transactions on Power Systems. 2019; 34 (4):2790-2801.
Chicago/Turabian StyleHongBin Sun; Qinglai Guo; Junjian Qi; Venkataramana Ajjarapu; Richard Bravo; Joe Chow; Zhengshuo Li; Rohit Moghe; Ehsan Nasr-Azadani; Ujjwol Tamrakar; Glauco N. Taranto; Reinaldo Tonkoski; Gustavo Valverde; Qiuwei Wu; Guangya Yang. 2019. "Review of Challenges and Research Opportunities for Voltage Control in Smart Grids." IEEE Transactions on Power Systems 34, no. 4: 2790-2801.
The rapid transition towards an inverter-dominated power system has reduced the inertial response capability of modern power systems. As a solution, inverters are equipped with control strategies, which can emulate inertia by exchanging power with the grid based on frequency changes. This paper discusses the various current control techniques for application in these systems, known as virtual inertia systems. Some classic control techniques like the proportional-integral, the proportional-resonant, and the hysteresis control are presented first, followed by the design and discussion of two more advanced control techniques based on model prediction and machine learning, respectively. MATLAB/Simulink-based simulations are performed, and results are presented to compare these control techniques in terms of harmonic performance, switching frequency, and transient response.
Ujjwol Tamrakar; Dipesh Shrestha; Naresh Malla; Zhen Ni; Timothy M. Hansen; Indraman Tamrakar; Reinaldo Tonkoski. Comparative Analysis of Current Control Techniques to Support Virtual Inertia Applications. Applied Sciences 2018, 8, 2695 .
AMA StyleUjjwol Tamrakar, Dipesh Shrestha, Naresh Malla, Zhen Ni, Timothy M. Hansen, Indraman Tamrakar, Reinaldo Tonkoski. Comparative Analysis of Current Control Techniques to Support Virtual Inertia Applications. Applied Sciences. 2018; 8 (12):2695.
Chicago/Turabian StyleUjjwol Tamrakar; Dipesh Shrestha; Naresh Malla; Zhen Ni; Timothy M. Hansen; Indraman Tamrakar; Reinaldo Tonkoski. 2018. "Comparative Analysis of Current Control Techniques to Support Virtual Inertia Applications." Applied Sciences 8, no. 12: 2695.
Modern data centers consume large amounts of electricity, resulting in high operational costs. The efficiency of a data center power distribution system can be increased, and the operational cost reduced, if the number of power conversion stages can be minimized and more efficient converters, such as wide bandgap (WBG) converters, are used. This can be achieved by using DC distribution voltage at the rack level by eliminating extra conversion stages. In this paper, benchmarks for both AC and 380V DC data centers were developed and efficiency analyses were performed for an entire year. The impact of integrating photovoltaic (PV) systems into the data centers has also been analyzed in both cases in terms of efficiency. The results show that 380V DC data centers are more efficient than AC data centers with and without PV integration. Furthermore, the reliability of an AC system was compared to a 380V DC architecture with Tier-IV standard. Monte-Carlo simulations were used to perform reliability analyses for different levels of redundancy in the Uninterruptible Power Supply (UPS) system for both cases. The simulation results showed that the 380V DC distribution system had a higher level of reliability than the AC distribution system in data centers.
Bijen R. Shrestha; Ujjwol Tamrakar; Timothy M. Hansen; Bishnu P. Bhattarai; Sean James; Reinaldo Tonkoski. Efficiency and Reliability Analyses of AC and 380 V DC Distribution in Data Centers. IEEE Access 2018, 6, 63305 -63315.
AMA StyleBijen R. Shrestha, Ujjwol Tamrakar, Timothy M. Hansen, Bishnu P. Bhattarai, Sean James, Reinaldo Tonkoski. Efficiency and Reliability Analyses of AC and 380 V DC Distribution in Data Centers. IEEE Access. 2018; 6 (99):63305-63315.
Chicago/Turabian StyleBijen R. Shrestha; Ujjwol Tamrakar; Timothy M. Hansen; Bishnu P. Bhattarai; Sean James; Reinaldo Tonkoski. 2018. "Efficiency and Reliability Analyses of AC and 380 V DC Distribution in Data Centers." IEEE Access 6, no. 99: 63305-63315.
The number of data centers is increasing at an alarming rate, causing an ever increase in the operating costs. Several works in literature propose the use of data centers as a virtual power plant (VPP) and their participation in the power market. A day-ahead load forecasting is an integral part of the energy management system (EMS) of data centers providing a baseline to schedule energy resources and thus reducing operating costs. Traditional methods of load forecasting are not suitable for a data center load due to its high variability and a difference in service from the utility load. Hidden Markov model (HMM) is a very flexible tool for modeling heterogeneous data, which is especially useful when the response is highly variable. Here, we propose an HMM to forecast the day-ahead load of a data center to assist in scheduling of available resources. A case study on the data center at National Renewable Energy Laboratory (NREL) - Research Support Facility (RSF) resulted in an annual average mean percentage absolute errors (MAPE) of 2.93% and 3.52% for two models proposed.
Abhilasha Bajracharya; Riaz Ahmed Khan; Semhar Michael; Reinaldo Tonkoski. Forecasting Data Center Load Using Hidden Markov Model. 2018 North American Power Symposium (NAPS) 2018, 1 -5.
AMA StyleAbhilasha Bajracharya, Riaz Ahmed Khan, Semhar Michael, Reinaldo Tonkoski. Forecasting Data Center Load Using Hidden Markov Model. 2018 North American Power Symposium (NAPS). 2018; ():1-5.
Chicago/Turabian StyleAbhilasha Bajracharya; Riaz Ahmed Khan; Semhar Michael; Reinaldo Tonkoski. 2018. "Forecasting Data Center Load Using Hidden Markov Model." 2018 North American Power Symposium (NAPS) , no. : 1-5.
The increase in the penetration of photovoltaics (PVs) and wind energy resources has decreased the inertia of power systems and made them inverter-based. This makes the modern grid susceptible to frequency instability when facing generation-load imbalances. In this paper, we provide an overview of the changing trends in frequency response and frequency control strategies in the modern power grid under high renewable penetrations. Virtual inertia emulation through Energy Storage Systems (ESSs), which have fast-ramping capabilities, is reviewed as a potential solution to the frequency instability issue. Recent grid codes and rules related to fast frequency services in the power system are discussed. A case study of the PJM interconnection, which was one of the first ISOs/RTOs to introduce the use of ESSs for frequency response, is then presented. The challenges faced to properly procure and reward such fast frequency response services in the PJM interconnection is analyzed in detail.
Andre Luna; Ujjwol Tamrakar; Timothy M. Hansen; Reinaldo Tonkoski. Frequency Response in Grids with High Penetration of Renewable Energy Sources. 2018 North American Power Symposium (NAPS) 2018, 1 -5.
AMA StyleAndre Luna, Ujjwol Tamrakar, Timothy M. Hansen, Reinaldo Tonkoski. Frequency Response in Grids with High Penetration of Renewable Energy Sources. 2018 North American Power Symposium (NAPS). 2018; ():1-5.
Chicago/Turabian StyleAndre Luna; Ujjwol Tamrakar; Timothy M. Hansen; Reinaldo Tonkoski. 2018. "Frequency Response in Grids with High Penetration of Renewable Energy Sources." 2018 North American Power Symposium (NAPS) , no. : 1-5.
Virtual inertia based control of renewable energy sources (RESs) helps to enhance the frequency stability of power systems. In this paper, a Control Area Network (CAN) communication-based method is demonstrated to emulate virtual inertia using commercial off-the-shelf inverters. This allows the currently installed systems to be retrofitted with virtual inertia in a cost-effective manner which would allow for higher RES penetration in power systems. The proof-of-concept is demonstrated using a Xantrex XW6048 hybrid inverter/charger and OPAL-RT real-time digital simulator. Results show that CAN-based communication can be an effective way to reduce frequency variations in the power system.
Ujjwol Tamrakar; Fernando B. Dos Reis; Andre Luna; Dipesh Shrestha; Robert Fourney; Reinaldo Tonkoski. Virtual Inertia Emulation using Commercial Off-The-Shelf Inverters. 2018 IEEE Energy Conversion Congress and Exposition (ECCE) 2018, 1111 -1116.
AMA StyleUjjwol Tamrakar, Fernando B. Dos Reis, Andre Luna, Dipesh Shrestha, Robert Fourney, Reinaldo Tonkoski. Virtual Inertia Emulation using Commercial Off-The-Shelf Inverters. 2018 IEEE Energy Conversion Congress and Exposition (ECCE). 2018; ():1111-1116.
Chicago/Turabian StyleUjjwol Tamrakar; Fernando B. Dos Reis; Andre Luna; Dipesh Shrestha; Robert Fourney; Reinaldo Tonkoski. 2018. "Virtual Inertia Emulation using Commercial Off-The-Shelf Inverters." 2018 IEEE Energy Conversion Congress and Exposition (ECCE) , no. : 1111-1116.
Summary form only given. Photovoltaic (PV) systems integration is increasingly being used to reduce fuel consumption in diesel-based remote microgrids. However, uncertainty and low correlation of PV power availability with load reduces the benefits of PV integration. These challenges can be handled by introducing reserve. However, this leads to increased operational cost. Solar irradiance forecasting helps to reduce reserve requirement, thereby improving the utilization of PV energy. This paper presents a new solar irradiance forecasting method for remote microgrids based on the Markov switching model. This method uses locally available data to predict one-day-ahead solar irradiance for scheduling energy resources in remote microgrids. The model considers past solar irradiance data, clear sky irradiance, and Fourier basis expansions to create linear models for three regimes or states: high, medium, and low energy regimes for days corresponding to sunny, mildly cloudy, and extremely cloudy days, respectively. The case study for Brookings, SD, USA, discussed in this paper, resulted in an average mean absolute percentage error of 31.8% for five years, from 2001 to 2005, with higher errors during summer months than during winter months.
Ayush Shakya; Semhar Michael; Christopher Saunders; Douglas Armstrong; Prakash Pandey; Santosh Chalise; Reinaldo Tonkoski. Solar Irradiance Forecasting in Remote Microgrids Using Markov Switching Model. 2018 IEEE Power & Energy Society General Meeting (PESGM) 2018, 1 -1.
AMA StyleAyush Shakya, Semhar Michael, Christopher Saunders, Douglas Armstrong, Prakash Pandey, Santosh Chalise, Reinaldo Tonkoski. Solar Irradiance Forecasting in Remote Microgrids Using Markov Switching Model. 2018 IEEE Power & Energy Society General Meeting (PESGM). 2018; ():1-1.
Chicago/Turabian StyleAyush Shakya; Semhar Michael; Christopher Saunders; Douglas Armstrong; Prakash Pandey; Santosh Chalise; Reinaldo Tonkoski. 2018. "Solar Irradiance Forecasting in Remote Microgrids Using Markov Switching Model." 2018 IEEE Power & Energy Society General Meeting (PESGM) , no. : 1-1.
This paper presents the model-predictive optimal dispatch of a behind-the-meter energy storage (BMES) system considering onsite generation/load variabilities and forecasting uncertainties. First, onsite generation and consumption are forecasted for a given facility with different confidence level using auto-regressive integrated moving average model. Subsequently, the cost-optimal dispatch of BMES is computed considering the forecasting uncertainties, cost of energy, cost of battery degradation, and behind-the-meter (BTM) services. In particular, the BMES is deployed for multiple BTM services, including peak-load reductions, smoothing intermittencies from onsite renewables, and load shaping of given facility. A mixed-integer non-linear programming based optimization is formulated and solved in GAMS using KNITRO solver to compute the cost-optimal BMES dispatch. The performance of the proposed method is investigated through a 24-hour time-series simulation in a co-simulation environment (GAMS, MATLAB, and R) using operational data of a residential consumer. The results demonstrate that the proposed method can simultaneously maximize BMES operational benefits and provide insights for sizing resources to compensate power imbalances of a facility.
Bishnu P. Bhattarai; Sumit Paudyal; Kurt S. Myers; Robert J. Turk; Reinaldo Tonkoski. Model Predictive Optimal Dispatch of Behind-the-Meter Energy Storage Considering Onsite Generation Uncertainties. 2018 IEEE Power & Energy Society General Meeting (PESGM) 2018, 1 -5.
AMA StyleBishnu P. Bhattarai, Sumit Paudyal, Kurt S. Myers, Robert J. Turk, Reinaldo Tonkoski. Model Predictive Optimal Dispatch of Behind-the-Meter Energy Storage Considering Onsite Generation Uncertainties. 2018 IEEE Power & Energy Society General Meeting (PESGM). 2018; ():1-5.
Chicago/Turabian StyleBishnu P. Bhattarai; Sumit Paudyal; Kurt S. Myers; Robert J. Turk; Reinaldo Tonkoski. 2018. "Model Predictive Optimal Dispatch of Behind-the-Meter Energy Storage Considering Onsite Generation Uncertainties." 2018 IEEE Power & Energy Society General Meeting (PESGM) , no. : 1-5.
Energy storage systems (ESSs) play a significant role in a remote microgrid's energy management system (EMS) by improving its reliability and energy efficiency. Lead-acid batteries are commonly used as ESS in remote microgrids due to comparatively low investment costs. However, the real-time operating conditions of lead-acid (PbA) batteries are quite severe than the standard test conditions which impacts the performance of an EMS and degrades the battery faster. The Schiffer weighted Ah-throughput model was considered in this paper, introducing different weight factors to analyze the operating conditions of PbA batteries. This paper presents the economical aspects of weekly, bi-weekly, monthly, and threshold crossing battery cycling strategies on PbA battery operating conditions. Its impact on the yearly operational costs of a remote microgrid and the battery lifetime are analyzed. Results showed that, effective battery cycling strategy can reduce the yearly operational cost by about 1.2% ($1,275) and increase the battery lifetime by 3.47 years. Hence, in the long run, it will reduce the expensive battery replacement cost and will maximize the profit of the system.
Habib Ullah; Santosh Chalise; Ujjwol Tamrakar; Reinaldo Tonkoski. Impact of Battery Operating Conditions on Remote Microgrid’s Energy Management System. 2018 IEEE Power & Energy Society General Meeting (PESGM) 2018, 1 -5.
AMA StyleHabib Ullah, Santosh Chalise, Ujjwol Tamrakar, Reinaldo Tonkoski. Impact of Battery Operating Conditions on Remote Microgrid’s Energy Management System. 2018 IEEE Power & Energy Society General Meeting (PESGM). 2018; ():1-5.
Chicago/Turabian StyleHabib Ullah; Santosh Chalise; Ujjwol Tamrakar; Reinaldo Tonkoski. 2018. "Impact of Battery Operating Conditions on Remote Microgrid’s Energy Management System." 2018 IEEE Power & Energy Society General Meeting (PESGM) , no. : 1-5.
Data centers have significant capital investments in large underutilized energy resources in the form of backup generators and batteries. In this paper, we propose to use these energy resources in demand response (DR) by operating a data center as a virtual power plant (VPP). An optimization model is designed which schedules the energy resources on a day-ahead basis using forecasted values of both renewable energy sources and the data center load for participation of the data center in DR. This optimization model also incorporates realtime dispatch of units to handle variations during operation. An improved battery cost model is designed and implemented as a soft constraint in the VPP energy management system (EMS) model, ensuring that the batteries' use in DR does not affect their float life. A case study is conducted in which the data center is connected to bus 8 of the modified IEEE 30-bus system. The results show that real-time operation of a data center participating in DR significantly reduces the operational cost, especially during network congestion, without causing battery degradation.
Prajina Tandukar; Labi Bajracharya; Timothy M. Hansen; Robert Fourney; Ujjwol Tamrakar; Reinaldo Tonkoski. Real-time Operation of a Data Center as Virtual Power Plant Considering Battery Lifetime. 2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM) 2018, 81 -86.
AMA StylePrajina Tandukar, Labi Bajracharya, Timothy M. Hansen, Robert Fourney, Ujjwol Tamrakar, Reinaldo Tonkoski. Real-time Operation of a Data Center as Virtual Power Plant Considering Battery Lifetime. 2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM). 2018; ():81-86.
Chicago/Turabian StylePrajina Tandukar; Labi Bajracharya; Timothy M. Hansen; Robert Fourney; Ujjwol Tamrakar; Reinaldo Tonkoski. 2018. "Real-time Operation of a Data Center as Virtual Power Plant Considering Battery Lifetime." 2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM) , no. : 81-86.
Studies had shown that the transient stability of a PV-Hydro micro-grid could be improved using a virtual synchronous machine (VSM), by injecting virtual inertia into the system. In the case of an interconnected system with multiple numbers of PV-Hydro micro-grid, a number of VSMs need to be operated in parallel. The parallel operated VSMs shall share the transient load in proportion to their respective capacities. Otherwise, the storage battery of one VSM will discharge more and other storage battery will be less discharged. This paper presents a control logic for parallel operated VSMs so that they share the transient load in proportion to the capacity of respective VSMs. Frequency droop control approach is used in the control logic to ensure proper load sharing. The control logic is simulated in MATLAB\ Simulink and results show that the frequency droop control approach is good enough for parallel operation of VSMs.
Prabin Adhikari; Suresh Prajapati; Indraman Tamrakar; Ujjwol Tamrakar; Reinaldo Tonkoski. Parallel operation of virtual synchronous machines with frequency droop control. 2017 7th International Conference on Power Systems (ICPS) 2017, 116 -120.
AMA StylePrabin Adhikari, Suresh Prajapati, Indraman Tamrakar, Ujjwol Tamrakar, Reinaldo Tonkoski. Parallel operation of virtual synchronous machines with frequency droop control. 2017 7th International Conference on Power Systems (ICPS). 2017; ():116-120.
Chicago/Turabian StylePrabin Adhikari; Suresh Prajapati; Indraman Tamrakar; Ujjwol Tamrakar; Reinaldo Tonkoski. 2017. "Parallel operation of virtual synchronous machines with frequency droop control." 2017 7th International Conference on Power Systems (ICPS) , no. : 116-120.
This paper aims to present an analytical study about the D-converter, including qualitative and quantitative analysis, considering the operation in continuous conduction mode, which will culminate into a design method proposal for this converter. Recently recommended for applications in photovoltaic power generation systems, due to its low input current ripple levels, the D-converter associated with photovoltaic modules ends up reducing the global losses of the photovoltaic conversion system. The D-converter is not a novel topology. However, it was not possible to identify in the references a detailed description about this converter, even though it is only briefly mentioned among many other converters.
Fernando S. Dos Reis; Henrique G. Cabral; Silvio C. A. Dutra; Eduardo G. Nery; Vanderlei A. Vieira; Aline C. Pan; Reinaldo Tonkoski. The D-converter in CCM: Analysis, design and results. 2017 Brazilian Power Electronics Conference (COBEP) 2017, 1 -6.
AMA StyleFernando S. Dos Reis, Henrique G. Cabral, Silvio C. A. Dutra, Eduardo G. Nery, Vanderlei A. Vieira, Aline C. Pan, Reinaldo Tonkoski. The D-converter in CCM: Analysis, design and results. 2017 Brazilian Power Electronics Conference (COBEP). 2017; ():1-6.
Chicago/Turabian StyleFernando S. Dos Reis; Henrique G. Cabral; Silvio C. A. Dutra; Eduardo G. Nery; Vanderlei A. Vieira; Aline C. Pan; Reinaldo Tonkoski. 2017. "The D-converter in CCM: Analysis, design and results." 2017 Brazilian Power Electronics Conference (COBEP) , no. : 1-6.