Browsing by Author "Canizares, Claudio A."

Now showing 1 - 20 of 93

A Centralized Energy Management System for Isolated Microgrids
(Institute of Electrical and Electronics Engineers (IEEE), 2014-04-25) Olivares, Daniel E.; Canizares, Claudio A.; Kazerani, Mehrdad
This paper presents the mathematical formulation of the microgrid's energy management problem and its implementation in a centralized Energy Management System (EMS) for isolated microgrids. Using the model predictive control technique, the optimal operation of the microgrid is determined using an extended horizon of evaluation and recourse, which allows a proper dispatch of the energy storage units. The energy management problem is decomposed into Unit Commitment (UC) and Optimal Power Flow (OPF) problems in order to avoid a mixed-integer non-linear formulation. The microgrid is modeled as a three-phase unbalanced system with presence of both dispatchable and non-dispatchable distributed generation. The proposed EMS is tested in an isolated microgrid based on a CIGRE medium-voltage benchmark system. Results justify the need for detailed three-phase models of the microgrid in order to properly account for voltage limits and procure reactive power support.
A Knowledge-Based Framework for Power Flow and Optimal Power Flow Analyses
(Institute of Electrical and Electronics Engineers (IEEE), 2016-04-07) Vaccaro, Alfredo; Canizares, Claudio A.
This paper proposes the application of formal methods for knowledge discovery from large quantity of data to reduce the complexity of power flow (PF) and optimal power flow (OPF) problems. In particular, a knowledge-based paradigm for PF and OPF analyses is used to extract complex features, hidden relationships, and useful hypotheses potentially describing regularities in the problem solutions from operation data-sets. This is realized by designing a knowledge-extraction process based on principal components analysis. The structural knowledge extracted by this process is then used to project the problem equations into a domain in which these equations can be solved more effectively. In this new domain, the cardinality of the PF and OPF problem is sensibly reduced and, consequently, the problem solutions can be obtained more efficiently. The effectiveness of the proposed framework is demonstrated with numerical results obtained for realistic power networks for several operating conditions.
A Novel Affine Arithmetic Method to Solve Optimal Power Flow Problems With Uncertainties
(Institute of Electrical and Electronics Engineers (IEEE), 2014-05-02) Pirnia, Mehrdad; Canizares, Claudio A.; Bhattacharya, Kankar; Vaccaro, Alfredo
An affine arithmetic (AA) method is proposed in this paper to solve the optimal power flow (OPF) problem with uncertain generation sources. In the AA-based OPF problem, all the state and control variables are treated in affine form, comprising a center value and the corresponding noise magnitudes, to represent forecast, model error, and other sources of uncertainty without the need to assume a probability density function (pdf). The proposed AA-based OPF problem is used to determine the operating margins of the thermal generators in systems with uncertain wind and solar generation dispatch. The AA-based approach is benchmarked against Monte Carlo simulation (MCS) intervals in order to determine its effectiveness. The proposed technique is tested and demonstrated on the IEEE 30-bus system and also a real 1211-bus European system.
A Range Arithmetic-Based Optimization Model for Power Flow Analysis Under Interval Uncertainty
(Institute of Electrical and Electronics Engineers (IEEE), 2012-09-18) Vaccaro, Alfredo; Canizares, Claudio A.; Bhattacharya, Kankar
This paper presents a novel framework based on range arithmetic for solving power flow problems whose input data are specified within real compact intervals. Reliable interval bounds are computed for the power flow problem, which is represented as an optimization model with complementary constraints to properly represent generator bus voltage controls, including reactive power limits and voltage recovery processes. It is demonstrated that the lower and upper bounds of the power flow solutions can be obtained by solving two determinate optimization problems. Several numerical results are presented and discussed, demonstrating the effectiveness of the proposed methodology and comparing it to a previously proposed affine arithmetic based solution approach.
A Robust Optimization Approach for Planning the Transition to Plug-in Hybrid Electric Vehicles
(Institute of Electrical and Electronics Engineers (IEEE), 2011-02-28) Hajimiragha, Amir H.; Canizares, Claudio A.; Fowler, Michael W.; Moazeni, Somayeh; Elkamel, Ali
This paper proposes a new technique to analyze the electricity and transport sectors within a single integrated framework to realize an environmentally and economically sustainable integration of plug-in hybrid electric vehicles (PHEVs) into the electric grid, considering the most relevant planning uncertainties. The method is based on a comprehensive robust optimization planning that considers the constraints of both the electricity grid and the transport sector. The proposed model is justified and described in some detail, applying it to the real case of Ontario, Canada, to determine Ontario's grid potential to support PHEVs for the planning horizon 2008-2025.
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.
A Sustainable Energy Management System for Isolated Microgrids
(Institute of Electrical and Electronics Engineers (IEEE), 2017-04-12) Solanki, Bharatkumar V.; Bhattacharya, Kankar; Canizares, Claudio A.
In this paper, the equivalent CO2 emission models for fossil-fuel-based distributed generator units are developed considering their individual emission characteristic and fuel consumption. These models are then integrated within a microgrid energy management system (EMS) model. Constant energy, demand shifting load models are further integrated in the EMS to examine the possible impact of demand response (DR) on the total system emissions and economics of a microgrid. Thus, the impacts of including the developed emission models on the operation of an isolated microgrid, equivalent CO2 emissions, and costs are examined considering five different operating strategies. The proposed operating strategies are validated on a modified CIGRE medium voltage benchmark system. The results obtained highlight the effectiveness of the proposed EMS and also demonstrate the impact of DR on emissions and costs.
A vector energy function approach for security analysis of AC/DC systems
(Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) DeMarco, Christopher L.; Canizares, Claudio A.
The authors examine dynamic behavior in system models that reflect reasonably detailed third-order high-voltage DC (HVDC) dynamics along with AC system models that include reactive flows, and frequency and voltage-dependent load models. A vector Lyapunov function approach is used to define a system-wide energy function that can be used for general security analysis. They describe the derivation of individual component Lyapunov functions for simplified models of HVDC links connected to infinitely strong AC systems, along with a standard AC only system Lyapunov function. A novel method of obtaining weighting coefficients to sum these components for the overall system energy function is proposed. Use of the new energy function for transient stability and security analysis was illustrated in a test system.
Advantages and disadvantages of using various computer tools in electrical engineering courses
(Institute of Electrical and Electronics Engineers (IEEE), 1997-08-31) Canizares, Claudio A.; Faur, Zeno T.
This paper discusses different computer tools used to help deliver, administer, and teach the material covered in two basic undergraduate courses in electrical engineering. The computer facilities, programs and tutorials developed are discussed; however, the paper concentrates more on analyzing the results of using these tools in the student learning process. The students' marks and the results of several student surveys, as well as the teaching staff's observations, are used to evaluate the usefulness of the different tools and determine their advantages and disadvantages. Some unexpected results regarding the actual students' use of these tools are also presented and thoroughly analyzed.
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 Affine Arithmetic-Based Energy Management System for Isolated Microgrids
(Institute of Electrical and Electronics Engineers (IEEE), 2018-03-15) Romero-Quete, David; Canizares, Claudio A.
This paper presents a mathematical formulation of an energy management system (EMS) for isolated microgrids, which addresses uncertainty using the affine arithmetic (AA) method. The proposed EMS algorithm is based on an AA unit commitment (AAUC) problem for day-ahead dispatch, using uncertainty intervals of both load and renewable energy (RE) to provide robust commitment and dispatch solutions in AA form, which are feasible for all the possible realizations within the predetermined uncertainty bounds. A real-time dispatch solution is then found by the proposed algorithm, which computes the noise symbols values of the affine forms obtained by the AAUC, based on the current and actual load and RE power levels and available reserves. If the actual forecast error is outside the uncertainly bounds considered in the AAUC solution process, leading to possible load and/or RE curtailment, the AAUC is recalculated with updated forecast information. The proposed AA-based EMS is tested on a modified CIGRE microgrid benchmark and is compared against day-ahead deterministic, model predictive control (MPC), stochastic optimization, and stochastic-MPC approaches. The simulation results show that the proposed EMS provides robust and adequate cost-effective solutions, without the need of frequent re-calculations as with MPC-based approaches, or assumptions regarding statistical characteristics of the uncertainties as in the case of stochastic optimization.
An Affine Arithmetic-Based Framework for Uncertain Power Flow and Optimal Power Flow Studies
(Institute of Electrical and Electronics Engineers (IEEE), 2016-05-10) Vaccaro, Alfredo; Canizares, Claudio A.
This paper proposes a unified framework based on affine arithmetic for computing reliable enclosures of uncertain power flow (PF) and optimal power flow (OPF) solutions. The main idea is to formulate a generic mathematical programming problem under uncertainty by means of equivalent deterministic problems, and to identify the affine forms describing the data uncertainty by means of a signal processing technique based on principal components analysis. Compared to existing solution algorithms, this formulation presents greater flexibility, as it allows to find feasible solutions and inclusion of multiple equality and inequality constraints, and reduce the approximation errors to obtain better PF and OPF solution enclosures. Detailed numerical results are presented and discussed using a variety of realistic test systems, demonstrating the effectiveness of the proposed methodologies and comparing it to existing techniques for uncertain PF and OPF analysis.
An Affine Arithmetic-Based Methodology for Reliable Power Flow Analysis in the Presence of Data Uncertainty
(Institute of Electrical and Electronics Engineers (IEEE), 2009-11-17) Vaccaro, Alfredo; Canizares, Claudio A.; Villacci, Domenico
Power flow studies are typically used to determine the steady state or operating conditions of power systems for specified sets of load and generation values, and is one of the most intensely used tools in power engineering. When the input conditions are uncertain, numerous scenarios need to be analyzed to cover the required range of uncertainty. Under such conditions, reliable solution algorithms that incorporate the effect of data uncertainty into the power flow analysis are required. To address this problem, this paper proposes a new solution methodology based on the use of affine arithmetic, which is an enhanced model for self-validated numerical analysis in which the quantities of interest are represented as affine combinations of certain primitive variables representing the sources of uncertainty in the data or approximations made during the computation. The application of this technique to the power flow problem is explained in detail, and several numerical results are presented and discussed, demonstrating the effectiveness of the proposed methodology, especially in comparison to previously proposed interval arithmetic's techniques.
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.
Application of a Stability-Constrained Optimal Power Flow to Tuning of Oscillation Controls in Competitive Electricity Markets
(Institute of Electrical and Electronics Engineers (IEEE), 2007-10-29) Kodsi, Sameh K. M.; Canizares, Claudio A.
A novel technique based on a stability-constrained Optimum Power Flow (OPF) algorithm that properly captures important rotor angle and voltage stability conditions is proposed and described. The application of this technique to the optimal tuning of both Power System Stabilizers (PSS) and thyristor controlled series compensators (TCSC) to damp power system oscillations within the context of competitive electricity markets is proposed and discussed as well. The proposed technique is tested on the IEEE 14-bus benchmark system and compared with a "standard" OPF algorithm. The results obtained demonstrate the advantages of the proposed technique over existent dispatching techniques from the point of view of power dispatch and system stability conditions, and especially locational marginal prices.
Battery Energy Storage System Models for Microgrid Stability Analysis and Dynamic Simulation
(Institute of Electrical and Electronics Engineers (IEEE), 2017-08-14) Farrokhabadi, Mostafa; Konig, Sebastian; Canizares, Claudio A.; Bhattacharya, Kankar; Leibfried, Thomas
With the increasing importance of battery energy storage systems (BESS) in microgrids, accurate modeling plays a key role in understanding their behavior. This paper investigates and compares the performance of BESS models with different depths of detail. Specifically, several models are examined: an average model represented by voltage sources; an ideal dc source behind a voltage source converter; a back-to-back buck/boost and bidirectional three-phase converter, with all models sharing the same control system and parameters; and two additional proposed models where the switches are replaced by dependent sources to help analyze the differences observed in the performance of the models. All these models are developed in PSCAD and their performances are simulated and compared considering various issues such as voltage and frequency stability and total harmonic distortion in a benchmark test microgrid. It is shown through simulation results and eigenvalue studies that the proposed models can exhibit a different performance, especially when the system is heavily loaded, highlighting the need for more accurate modeling under certain microgrid conditions.
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.