Browsing by Author "Canizares, Claudio A."

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A study of TCSC controller design for power system stability improvement
(Institute of Electrical and Electronics Engineers (IEEE), 2003-11-17) Del Rosso, Alberto D.; Canizares, Claudio A.; Dona, Victor M.
Different control aspects related to the use of TCSC for stability improvement of power systems are addressed in this paper. A novel hierarchical control designed for both dynamic and steady state stability enhancement is proposed, and a complete analysis is presented of various locally measurable input signals that can be used for the controller. Control strategies to mitigate adverse interactions among the TCSC hierarchical controls are also presented. A simplified model of the Argentinian high voltage interconnected system is used to illustrate the ideas presented in the paper.
Aggregated BESS Dynamic Models for Active Distribution Network Studies
(Institute of Electrical and Electronics Engineers (IEEE), 2020-12-31) Calero, Fabian; Canizares, Claudio A.; Bhattacharya, Kankar
This article proposes a transmission-system-level aggregated model of Battery Energy Storage Systems (BESSs) distributed through Active Distribution Networks (ADNs), to study the dynamic performance and services provided by these systems to power grids. ADNs comprise intelligent loads, local generation, particularly solar PV, and BESSs, which can provide different services to transmission grids, including voltage control, oscillation damping, frequency regulation, and active and reactive power injections. Proper equivalent models of the ADN components allow to evaluate the impact and integration of these networks on power grids. In this article, ADN's measurements of the aggregated response of the BESSs at the boundary bus with the transmission system are used to develop an aggregated black-box model based on two Neural Networks (NNs), one for active power and another for reactive power, with their optimal topology obtained using a Genetic Algorithm (GA). Detailed simulations are performed, using a commercial-grade software for power system analysis, of multiple BESSs connected to a CIGRE benchmark ADN connected to a bus of the 9-bus WSCC benchmark transmission network; the test ADN is then replaced by the proposed black-box model, with aggregated models of the loads and PV generation, demonstrating that the proposed model can accurately reproduce the results obtained.
An Effective Controllable Grid Interface for Microgrids
(Institute of Electrical and Electronics Engineers (IEEE), 2022-08-31) Tamimi, Behnam; Gu, Hanwen; Canizares, Claudio A.
The interest in the integration of distributed power generation and microgrids into power grids has significantly increased. In this context, interfacing microgrids with a host grid is of significant relevance, and therefore, in this paper, a cost-effective controllable grid interface for microgrids is proposed, modeled, and studied under various conditions, including smooth and abrupt power fluctuations, faults, and interface tripping. The proposed interface, named Microgrid Connector Controller (MGC), is an adequate and affordable alternative to the existing Back-to-Back (B2B) microgrid-grid interface, at a fraction of its capital costs. Thus, the proposed MGC’s performance is compared a B2B interface through detailed time-domain simulations in a realistic benchmark test system to demonstrate the controller’s capabilities. Compared with B2B, MGC’s direct frequency synchronization and power and voltage control capabilities makes it easier for microgrid operators to satisfy required standards and reduce wear and tear in grid equipment and customer loads. Finally, the MGC’s lower voltage ratings may translate into significantly smaller size and thus easier logistics and lower costs.
An Energy Management System for Isolated Microgrids With Thermal Energy Resources
(Institute of Electrical and Electronics Engineers (IEEE), 2020-02-11) Violante, Walter; Canizares, Claudio A.; Trovato, Michele A.; Forte, Giuseppe
A novel Energy Management System (EMS) model for an isolated microgrid, integrating thermal energy resources, such as Combined Heat and Power (CHP) units, boilers, Heat Pumps (HPs), and Thermal Storage System (TSS), while considering thermal load models, is proposed in this paper. The developed EMS is tested and validated with a real testbed microgrid located in Bari, Italy, which supplies both electricity and heat to a building at the Politecnico di Bari. The proposed EMS aims to minimize the fuel cost and includes thermal comfort requirements and building models, along with suitable models for CHP units and hot water-based TSS, based on an optimization problem formulated as a Mixed Integer Linear Programming (MILP) problem, which is readily handled with commercial solvers, making the EMS fit for online applications. The proposed EMS is compared with an electrical-only EMS, i.e., a practical EMS that does not include thermal systems, with the simulations carried out for different winter days demonstrating the economic benefits of accounting for thermal system models in a microgrid EMS, resulting in significant savings in the daily fuel cost.
Analysis of SVC and TCSC controllers in voltage collapse
(Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) Canizares, Claudio A.; Faur, Zeno T.
This paper presents detailed steady-state models with controls of two flexible AC transmission system (FACTS) controllers, namely, static VAr compensators (SVCs) and thyristor controlled series capacitors (TCSCs), to study their effect on voltage collapse phenomena in power systems. Based on results at the point of collapse, design strategies are proposed for these two controllers, so that their location, dimensions and controls can be optimally defined to increase system loadability. A European system is used to illustrate the application of all proposed models and techniques.
Behind-the-meter compressed air energy storage feasibility and applications
(Elsevier, 2020-08-08) Anierobi, Chioma C.; Bhattacharya, Kankar; Canizares, Claudio A.
In this paper, the operations model of a behind-the-meter Small Scale Compressed Air Energy Storage (SS-CAES) facility is developed for an industrial customer with existing wells/caverns that can be re-purposed for air storage. The operations model seeks to minimize the electricity costs of the industrial customer, while determining the energy output and the corresponding charging and discharging decisions of the SS-CAES system. In order to examine the financial viability of a practical behind-the-meter SS-CAES facility, an economic analysis is carried out using real data of an industrial customer based in Ontario, Canada. Key parameters such as life cycle, CAES capacity and capital cost, and electricity price are considered for carrying out a sensitivity analysis, with the results showing that SS-CAES is economically viable for the current Ontario electricity tariff rate structure. The low capital cost of a SS-CAES project with a re-purposed storage cavern, and the high Global Adjustment charges levied in Ontario are shown to be a key determining factors for the economic feasibility of deployment of SS-CAES in Ontario.
Calculating optimal system parameters to maximize the distance to saddle-node bifurcations
(Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) Canizares, Claudio A.
This paper presents a new methodology to calculate parameters of a nonlinear system, so that its distance to a saddle-node bifurcation is maximized with respect to the particular parameters that drive the system to bifurcation. The technique is thoroughly justified, specifying the conditions when it can be applied and the numeric mechanisms to obtain the desired solutions. A comparison is also carried out between the proposed method and a known methodology to determine closest saddle-node bifurcations in a particular power system model, showing that the new technique is a generalization of the previous method. Finally, applications to power systems are discussed, particularly regarding the design of some FACTS devices, and a simple generator-line-load example is studied to illustrate the use of the proposed technique to determine the optimal shunt and/or series compensation to maximize distances to voltage collapse. The effect of the optimal compensation on the stability of the sample system is also analyzed.
Comparison of performance indices for detection of proximity to voltage collapse
(Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) Canizares, Claudio A.; De Souza, Antonio C.Z.; Quintana, Victor H.
The paper proposes a new test function to be used in an existent performance index for detection of proximity to a static voltage collapse point. This test function is based on a reduction of the load flow Jacobian with respect to the critical bus of a system. The test function is compared with known singular values and eigenvalues indices, and with other previously proposed test functions. A thorough analysis of the similarities, advantages, and disadvantages of all these indices and test functions is presented. The techniques are tested and compared on the IEEE 300 bus test system, showing the effect of system characteristics and limits in these indices and functions.
Comparison of PSS, SVC, and STATCOM controllers for damping power system oscillations
(Institute of Electrical and Electronics Engineers (IEEE), 2003-05-13) Mithulananthan, N.; Canizares, Claudio A.; Reeve, John; Rogers, Graham J.
This paper discusses and compares different control techniques for damping undesirable interarea oscillation in power systems by means of power system stabilizers (PSS), static VAr compensators (SVCs), and shunt static synchronous compensators (STATCOMs). The oscillation problem is analyzed from the point of view of Hopf bifurcations, an "extended" eigenanalysis to study different controllers, their locations, and the use of various control signals for the effective damping of these oscillations. The comparisons are based on the results obtained for the IEEE 50-machine, 145-bus test system, which is a benchmark for stability analysis.
Confidence Intervals Estimation in the Identification of Electromechanical Modes From Ambient Noise
(Institute of Electrical and Electronics Engineers (IEEE), 2008-04-22) Ghasemi, Hassan; Canizares, Claudio A.
This paper discusses the estimation of uncertainty intervals associated with the electromechanical modes identified from ambient data resulting from random load switching throughout the day in power systems. A connection between the second order statistical properties, including confidence intervals, of the identified electromechanical modes and the variance of the parameters of a selected linear model is demonstrated. The results of the presented method are compared with respect to the ones obtained from a Monte Carlo technique, showing its effectiveness in reducing the number of trials, which would be beneficial for online power system monitoring, as it can decrease the number of samples, thus ensuring that the system dynamics would not change significantly over the monitoring time window, and yielding more dependable results. Two test cases, namely, the two-area benchmark system and the IEEE 14-bus system, with different orders of the system identification model used, are utilized to demonstrate the effectiveness of the proposed methodology.
Distributed Computing Architecture for Optimal Control of Distribution Feeders With Smart Loads
(Institute of Electrical and Electronics Engineers (IEEE), 2016-09-28) Mosaddegh, Abolfazl; Canizares, Claudio A.; Bhattacharya, Kankar; Fan, Hongbing
This paper presents a distributed computing architecture for solving a distribution optimal power flow (DOPF) model based on a smart grid communication middleware (SGCM) system. The system is modeled as an unbalanced three-phase distribution system, which includes different kind of loads and various components of distribution systems. In this paper, fixed loads are modeled as constant impedance, current and power loads, and neural network models of controllable smart loads are integrated into the DOPF model. A genetic algorithm is used to determine the optimal solutions for controllable devices, in particular load tap changers, switched capacitors, and smart loads in the context of an energy management system for practical feeders, accounting for the fact that smart loads consumption should not be significantly affected by network constraints. Since the number of control variables in a realistic distribution power system is large, solving the DOPF for real-time applications is computationally expensive. Hence, to reduce computational times, a decentralized system with parallel computing nodes based on an SGCM system is proposed. Using a “MapReduce” model, the SGCM system runs the DOPF model, communicates between master and worker computing nodes, and sends/receives data among different parts of parallel computing system. Compared to a centralized approach, the proposed architecture is shown to yield better optimal solutions in terms of reducing energy losses and/or energy drawn from the substation within adequate practical run-times for a realistic test feeder.
Duck-Curve Mitigation in Power Grids With High Penetration of PV Generation
(Institute of Electrical and Electronics Engineers (IEEE), 2021-10-25) Calero, Ivan; Canizares, Claudio A.; Bhattacharya, Kankar; Baldick, Ross
Small-scale PV generation has become popular with residential customers in several jurisdictions with high solar radiation, as an alternative to improve their carbon footprint and reduce their electricity bills. However, massive deployment of such distributed generation is creating a particular and undesirable shape in the net demand, which deepens at hours of peak solar PV injections at noon and suddenly rises towards the evening, known as the “duck curve”. Hence, this paper investigates the use of pre-cooling strategies in residential households to mitigate the duck-curve effects. To this aim, appropriate thermal models and simulations of houses are first developed and carried out to demonstrate the technical feasibility of pre-cooling in a house with a typical configuration, based on the Smart Residential Load Simulator (SRLS) developed at the University of Waterloo. Then, an aggregation technique is proposed to evaluate the effects on a large grid of different penetration levels of PV, and pre-cooling approaches to manage the duck-curve in California and Texas, concluding that such techniques are capable of substantially flattening the system net demand curve.
Dynamic Modeling of Battery Energy Storage and Applications in Transmission Systems
(Institute of Electrical and Electronics Engineers (IEEE), 2020-08-13) Calero, Fabian; Canizares, Claudio A.; Bhattacharya, Kankar
In this paper, a Battery Energy Storage System (BESS) dynamic model is presented, which considers average models of both Voltage Source Converter (VSC) and bidirectional buck-boost converter (dc-to-dc), for charging and discharging modes of operation. The dynamic BESS model comprises a simplified representation of the battery cells, which allows to simulate the effects of battery degradation, dc-to-dc converter, VSC, and the dynamics associated with the filter and transformer connecting the BESS to the grid. A decoupled dq-current control is used for the VSC, allowing the operation of the BESS in several modes, i.e., constant active and reactive power, constant power factor, voltage regulation, frequency regulation, oscillation damping, and a combination of the latter two. The proposed model is implemented in DSATools and tested for different contingencies on a benchmark system, and compared with a industry-grade BESS model used in power system dynamic studies. The importance of modeling the current control and dynamics of the dc-to-dc are demonstrated, especially when the battery cells are degraded due to, for instance, aging.
Effect of detailed power system models in traditional and voltage-stability-constrained optimal power-flow problems
(Institute of Electrical and Electronics Engineers (IEEE), 2003-02-28) Rosehart, William D.; Canizares, Claudio A.; Quintana, Victor H.
In this paper, detailed generator, exponential load, and static volt-ampere-reactive (VAr) compensator models are incorporated into traditional and voltage-stability-constrained optimal power-flow problems to study the effect that the different models have on costs and system-loadability. The proposed models are compared to typical models by means of a detailed analysis of the results obtained for two IEEE test systems; interior point methods are used to obtain numerical solutions of the associated optimization problems.
Energy Storage in Microgrids: Compensating for Generation and Demand Fluctuations While Providing Ancillary Services
(Institute of Electrical and Electronics Engineers (IEEE), 2017-08-16) Farrokhabadi, Mostafa; Solanki, Bharatkumar V.; Canizares, Claudio A.; Bhattacharya, Kankar; Koenig, Sebastian; Sauter, Patrick S.; Leibfried, Thomas; Hohmann, Soren
Driven by global environmental emission issues, energy access in remote communities, and tighter requirements for system resilience and reliability, electricity production is shifting from a centralized paradigm to a decentralized one. In this context, renewable energy sources (RESs) have proliferated over the past decade, exhibiting a steadily increasing trend. Thus, today, a large number of wind turbines and photovoltaic (PV) panels are connected to medium- (1-69 kV) and low-voltage (=1 kV) grids, with traditional integrated bulk power systems becoming decentralized in the presence of active distribution networks, where the flow of power is bidirectional between generators and "prosumers." In particular, with decreasing RES s costs, these technologies are becoming attractive solutions to bring energy to remote communities and/or replace expensive fossil-fuel-based generators. However, RES s such as wind and solar are intermittent sources of energy, difficult to predict, and prone to large output fluctuations-therefore, significantly affecting system voltage and frequency.
Equivalency of Continuation and Optimization Methods to Determine Saddle-Node and Limit-Induced Bifurcations in Power Systems
(Institute of Electrical and Electronics Engineers (IEEE), 2008-05-28) Avalos, Rafael J.; Canizares, Claudio A.; Milano, Federico; Conejo, Antonio J.
This paper presents a comprehensive and detailed study of an optimization-based approach to identify and analyze saddle-node bifurcations (SNBs) and limit-induced bifurcations (LIBs) of a power system model, which are known to be directly associated with voltage stability problems in these systems. Theoretical studies are presented, formally demonstrating that solution points obtained from an optimization model, which is based on complementarity constraints used to properly represent generators' voltage controls, correspond to either SNB or LIB points of this model. These studies are accomplished by proving that optimality conditions of these solution points yield the transversality conditions of the corresponding bifurcation points. A simple but realistic test system is used to numerically illustrate the theoretical discussions.
Frequency Regulation in Isolated Microgrids Through Optimal Droop Gain and Voltage Control
(Institute of Electrical and Electronics Engineers (IEEE), 2021-10-02) Alghamdi, Baheej; Canizares, Claudio A.
This article presents an adaptive active power droop controller and voltage setpoint control in isolated microgrids for optimal frequency response and stability after disturbances. The control scheme involves an optimal and model predictive control approach that continuously adjusts the active power droop gains and the voltage setpoints of Distributed Energy Resources (DERs) to maintain the frequency of the system within acceptable limits and enhance the primary frequency response of the system, while taking into account the active power sensitivity of the microgrid loads to the system's operating voltage. The proposed control scheme is tested, validated, and compared with previously proposed techniques using time-domain simulations for a test system based on a CIGRE medium voltage benchmark microgrid under different realistic conditions, demonstrating the advantages of the proposed approach.
Frequency Regulation Model of Bulk Power Systems With Energy Storage
(Institute of Electrical and Electronics Engineers (IEEE), 2021-08-30) Guzman E., Noela Sofia; Canizares, Claudio A.; Bhattacharya, Kankar; Sohm, Daniel
This paper presents a Frequency Regulation (FR) model of a large interconnected power system including Energy Storage Systems (ESSs) such as Battery Energy Storage Systems (BESSs) and Flywheel Energy Storage Systems (FESSs), considering all relevant stages in the frequency control process. Communication delays are considered in the transmission of the signals in the FR control loop and ESSs, and their State of Charge (SoC) management model is considered. The system, ESSs and SoC components are modelled in detail from a FR perspective. The model is validated using real system and ESSs data, based on a practical transient stability model of the North American Eastern Interconnection (NAEI), and the results show that the proposed model accurately represents the FR process of a large interconnected power network including ESS, and can be used for long-term FR studies. The impact of communication delays and SoC management of ESS facilities in the Area Control Error (ACE) is also studied and discussed, as well as the computational efficiency of the proposed FR model.
Frequency-Constrained Energy Management System for Isolated Microgrids
(Institute of Electrical and Electronics Engineers (IEEE), 2022-04-28) Cordova, Samuel; Canizares, Claudio A.; Lorca, Alvaro; Olivares, Daniel E.
Second-to-second power imbalances stemming from renewable generation can have a large impact on the frequency regulation performance of isolated microgrids, as these are characterized by low inertia and, more commonly nowadays, significant renewable energy penetration. Thus, the present paper develops a novel frequency-constrained Energy Management System (EMS) that takes into account the impact of short-term power fluctuations on the microgrid’s operation and frequency regulation performance. The proposed EMS model is based on accurate linear equations describing frequency deviation, rate-of-change-of-frequency, and regulation provision in daily microgrid operations. Dynamic simulations on a realistic CIGRE benchmark test system show the economic and reliability benefits of the presented EMS model, highlighting the need of incorporating fast power fluctuations and their impact on frequency dynamics in EMSs for sustainable isolated microgrids.
Ground Source Heat Pump Modeling, Operation, and Participation in Electricity Markets
(Institute of Electrical and Electronics Engineers (IEEE), 2021-12-07) Peralta, Dario; Canizares, Claudio A.; Bhattacharya, Kankar
Over the last decades, Ground Source Heat Pump (GSHP) systems have grown in popularity and acceptance worldwide, having the potential to bring about significant benefits, especially if these systems participate in electricity markets through a load aggregator to optimize their operations and provide services such as load shifting and demand reduction, as proposed here. In this context, GSHP systems can be considered as an economically viable and attractive alternative to existing Heating Ventilation and Air Conditioning (HVAC) systems for space heating/cooling in buildings and houses from an aggregator point of view. Hence, this paper presents a detailed mathematical model for a GSHP with a vertical U-pipe Ground Heat eXchanger (GHX) configuration to provide residential space heating/cooling, integrating several such GSHPs into a load aggregator model. Then, a two-stage operational strategy for the GSHP price-taker aggregator participating in day-ahead and real-time electricity markets is proposed, to determine the optimal annual heating/cooling load dispatch to control the temperatures for a community of houses that minimizes the aggregator’s cost. Detailed numerical studies and comparisons with HVAC systems are carried out to demonstrate the feasibility and benefits of the proposed aggregated operation of GSHPs in electricity markets.