Waterloo Research

Permanent URI for this collectionhttps://uwspace.uwaterloo.ca/handle/10012/9972

This is the University of Waterloo Research collection.

Waterloo faculty, students, and staff can contact us or visit the UWSpace guide to learn more about depositing their research.

NOTE: This collection does not include graduate Theses & Dissertations or Major Research Projects.

Browse

Now showing 1 - 20 of 2747

Point of collapse and continuation methods for large AC/DC systems
(Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) Canizares, Claudio A.; Alvarado, Fernando L.
The implementation of both point of collapse (PoC) methods and continuation methods for the computation of voltage collapse points (saddle-node bifurcations) in large AC/DC power systems is described. The performance of these methods is compared for real systems of up to 2158 buses. Computational details of the implementation of the PoC and continuation methods are detailed, and the unique problems encountered due to the presence of high-voltage direct-current (HVDC) transmission, area interchange power control, regulating transformers, and voltage and reactive power limits are discussed. The characteristics of a robust PoC power flow program are presented, and its application to detection and solution of voltage stability problems is demonstrated.
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 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.
Reactive Power and Voltage Control in Distribution Systems With Limited Switching Operations
(Institute of Electrical and Electronics Engineers (IEEE), 2009-03-31) Liu, M.B.; Canizares, C.A.; Huang, W.
An algorithm based on a nonlinear interior-point method and discretization penalties is proposed in this paper for the solution of the mixed-integer nonlinear programming (MINLP) problem associated with reactive power and voltage control in distribution systems to minimize daily energy losses, with time-related constraints being considered. Some of these constraints represent limits on the number of switching operations of transformer load tap changers (LTCs) and capacitors, which are modeled as discrete control variables. The discrete variables are treated here as continuous variables during the solution process, thus transforming the MINLP problem into an NLP problem that can be more efficiently solved exploiting its highly sparse matrix structure; a strategy is developed to round these variables off to their nearest discrete values, so that daily switching operation limits are properly met. The proposed method is compared with respect to other well-known MINLP solution methods, namely, a genetic algorithm and the popular GAMS MINLP solvers BARON and DICOPT. The effectiveness of the proposed method is demonstrated in the well-known PG&E 69-bus distribution network and a real distribution system in the city of Guangzhou, China, where the proposed technique has been in operation since 2003.
Sensitivity-Based Security-Constrained OPF Market Clearing Model
(Institute of Electrical and Electronics Engineers (IEEE), 2005-10-31) Milano, Federico; Canizares, Claudio A.; Conejo, Antonio J.
This paper proposes a novel technique for representing system security constraints that properly include voltage stability limits in the operation of competitive electricity markets. The market-clearing algorithm is modeled as a voltage stability constrained optimal power flow (OPF) problem, while the distance to the closest critical power flow solution is represented by means of a loading parameter and evaluated using a continuation power flow (CPF) technique. Sensitivities obtained at the OPF step are used to estimate power directions for the CPF method, while the CPF analysis provides the loading parameter to be used in the OPF problem based on an N-1 contingency criterion. The OPF and the CPF steps are repeated until the maximum loading parameter is found, thus providing optimal solutions considering both proper market conditions and security margins. Two benchmark systems with both supply and demand bidding are used to illustrate and test the proposed technique
Voltage stability constrained OPF market models considering contingency criteria
(Elsevier, 2004-12-22) Milano, Federico; Cañizares, Claudio A.; Invernizzi, Marco
This paper proposes two novel techniques for including contingencies in OPF-based electricity market computations and for the estimation of a “system-wide” available transfer capability (SATC). The OPF problem formulation includes voltage stability constraints and a loading parameter in order to ensure a proper stability margin for the market solution. Two methods are proposed. The first technique is an iterative approach and computes an SATC value based on an contingency criterion for an initial optimal operating condition, to then solve an OPF problem for the worst contingency case; this process is repeated until the changes in the SATC values are below a minimum threshold. The second approach solves a reduced number of OPF problems associated with contingency cases according to a ranking based on a power transfer sensitivity analysis of the transmission lines. Both methods are tested on a 6-bus system and on a realistic 129-bus Italian network model considering supply and demand side bidding. Local marginal prices and nodal congestion prices resulting from the proposed solutions as well as comparisons with results obtained by means of a standard OPF technique are also presented and discussed.
Multiobjective optimization for pricing system security in electricity markets
(Institute of Electrical and Electronics Engineers (IEEE), 2003-05-13) Milano, Federico; Canizares, Claudio A.; Invernizzi, Marco
This paper proposes a novel technique for representing system security in the operations of decentralized electricity markets, with special emphasis on voltage stability. An interior point method is used to solve the optimal power flow problem with a multiobjective function for maximizing both social benefit and the distance to maximum loading conditions. A six-bus system with both supply and demand-side bidding is used to illustrate the proposed technique for both elastic and inelastic demand, and a 129-bus test system that models the Italian HV transmission network is used for testing the practical applicability of the proposed method. The results obtained show that the proposed technique is able to improve system security while yielding better market conditions through increased transaction levels and improved locational marginal prices throughout the system.
Time dependence of controls to avoid voltage collapse
(Institute of Electrical and Electronics Engineers (IEEE), 2002-08-06) Vargas, Luis S.; Canizares, Claudio A.
In this paper, the effect of time dependence of control actions used to avoid voltage collapse, such as reactive power compensation and load shedding, is studied. A thorough justification of the phenomena under study is first presented with the help of a simple test system. The time dependence of the control actions is then studied in a real voltage collapse scenario of the Chilean Interconnected System (CIS), based on a reduced system model.
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.
Oscillatory Stability Limit Prediction Using Stochastic Subspace Identification
(Institute of Electrical and Electronics Engineers (IEEE), 2006-05-01) Ghasemi, Hassan; Canizares, Claudio A.; Moshref, Ali
Determining stability limits and maximum loading margins in a power system is important and can be of significant help for system operators for preventing stability problems. In this paper, stochastic subspace identification is employed to extract the critical mode(s) from the measured ambient noise without requiring artificial disturbances (e.g., line outages, generator tripping, and adding/removing loads), so that the identified critical mode may be used as an online index to predict the closest oscillatory instability. The proposed index is not only independent of system models and truly represents the actual system, but it is also computationally efficient. The application of the proposed index to several realistic test systems is examined using a transient stability program and PSCAD/EMTDC, which has detailed models that can capture the full dynamic response of the system. The results show the feasibility of using the proposed identification technique and index for online detection of proximity to oscillatory stability problems.
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.
Web-Based Security Cost Analysis in Electricity Markets
(Institute of Electrical and Electronics Engineers (IEEE), 2005-05-31) Chen, Hong; Canizares, Claudio A.; Singh, Ajit
Security cost analysis is important in electricity markets to address the correlation between market operation and power system operation. This paper proposes an efficient security cost analysis method and describes its implementation using a three-tier client/server architecture and up-to-date web technologies. The proposed security cost analysis is based on a system security index and its sensitivities with respect to certain system parameters. The web implementation allows easy and effective access by all market participants to make competitive decisions based on the security costs and sensitivity information obtained through the proposed security cost analysis techniques. The web implementation of the proposed method is successfully tested on a six-bus system and a 129-bus system.
Linear Performance Indices to Predict Oscillatory Stability Problems in Power Systems
(Institute of Electrical and Electronics Engineers (IEEE), 2004-05-04) Canizares, Claudio A.; Mithulananthan, N.; Milano, Federico; Reeve, John
Various indices are proposed and studied to detect and predict oscillatory instabilities associated with Hopf bifurcations (HBs) in power systems. A methodology is also presented to produce a linear profile for these indices. They are based on eigenvalue and singular values of the state and extended system matrices. Their application to several test power systems is presented to demonstrate their usefulness, particularly for online applications.
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.
Electricity market price volatility: The case of Ontario
(Elsevier, 2007-05-25) Zareipour, Hamidreza; Bhattacharya, Kankar; Cañizares, Claudio A.
Price volatility analysis has been reported in the literature for most competitive electricity markets around the world. However, no studies have been published yet that quantify price volatility in the Ontario electricity market, which is the focus of the present paper. In this paper, a comparative volatility analysis is conducted for the Ontario market and its neighboring electricity markets. Volatility indices are developed based on historical volatility and price velocity concepts, previously applied to other electricity market prices, and employed in the present work. The analysis is carried out in two scenarios: in the first scenario, the volatility indices are determined for the entire price time series. In the second scenario, the price time series are broken up into 24 time series for each of the 24 h and volatility indices are calculated for each specific hour separately. The volatility indices are also applied to the locational marginal prices of several pricing points in the New England, New York, and PJM electricity markets. The outcomes reveal that price volatility is significantly higher in Ontario than the three studied neighboring electricity markets. Furthermore, comparison of the results of this study with similar findings previously published for 15 other electricity markets demonstrates that the Ontario electricity market is one of the most volatile electricity markets world-wide. This high volatility is argued to be associated with the fact that Ontario is a single-settlement, real-time market.
Application of Public-Domain Market Information to Forecast Ontario's Wholesale Electricity Prices
(Institute of Electrical and Electronics Engineers (IEEE), 2006-11-30) Zareipour, H.; Canizares, C.A.; Bhattacharya, K.; Thomson, J.
This paper evaluates the usefulness of publicly available electricity market information in forecasting the hourly Ontario energy price (HOEP). In order to do so, relevant data from Ontario and its neighboring electricity markets, namely, New York, New England, and PJM electricity markets, are investigated, and a final set of explanatory variable candidates that are available before real-time are selected. Multivariate transfer function and dynamic regression models are employed to relate HOEP behavior to the selected explanatory variable candidates. Univariate ARIMA models are also developed for the HOEP. The HOEP models are developed on the basis of two forecasting horizons, i.e., 3 h and 24 h, and forecasting performance of the multivariate models is compared with that of the univariate models. The outcomes show that the market information publicly available before real-time can be used to improve HOEP forecast accuracy to some extent; however, unusually high or low prices remain unpredictable, and hence, the available data cannot lead to significantly more accurate forecasts. Nevertheless, the generated forecasts in this paper are significantly more accurate than currently available HOEP forecasts. To analyze the relatively low accuracy of the HOEP forecasts, comparisons are made with respect to ARIMA models developed for locational marginal prices (LMPs) of Ontario's three neighboring markets, and price volatility analyses are presented.
The Operation of Ontario's Competitive Electricity Market: Overview, Experiences, and Lessons
(Institute of Electrical and Electronics Engineers (IEEE), 2007-10-29) Zareipour, Hamidreza; Canizares, Claudio A.; Bhattacharya, Kankar
Competitive electricity markets have been operating in various countries for more than a decade, with every single electricity market presenting its own unique characteristics and features. This paper provides a comprehensive overview of the operational aspects of the Ontario electricity market, its unique features, and its outcomes for the first four years of operation. Several programs implemented in the Ontario market to improve efficiency, transparency, and competitiveness are analyzed, and the effectiveness of these programs are discussed.
Hydrogen storage for mixed wind–nuclear power plants in the context of a Hydrogen Economy
(Elsevier, 2008-08-15) Taljan, Gregor; Fowler, Michael; Cañizares, Claudio; Verbič, Gregor
A novel methodology for the economic evaluation of hydrogen production and storage for a mixed wind–nuclear power plant considering some new aspects such as residual heat and oxygen utilization is applied in this work. This analysis is completed in the context of a Hydrogen Economy and competitive electricity markets. The simulation of the operation of a combined nuclear–wind–hydrogen system is discussed first, where the selling and buying of electricity, the selling of excess hydrogen and oxygen, and the selling of heat are optimized to maximize profit to the energy producer. The simulation is performed in two phases: in a pre-dispatch phase, the system model is optimized to obtain optimal hydrogen charge levels for the given operational horizons. In the second phase, a real-time dispatch is carried out on an hourly basis to optimize the operation of the system as to maximize profits, following the hydrogen storage levels of the pre-dispatch phase. Based on the operation planning and dispatch results, an economic evaluation is performed to determine the feasibility of the proposed scheme for investment purposes; this evaluation is based on calculations of modified internal rates of return and net present values for a realistic scenario. The results of the present studies demonstrate the feasibility of a hydrogen storage and production system with oxygen and heat utilization for existent nuclear and wind power generation facilities.
The Feasibility of Hydrogen Storage for Mixed Wind-Nuclear Power Plants
(Institute of Electrical and Electronics Engineers (IEEE), 2008-08-31) Taljan, G.; Canizares, C.; Fowler, M.; Verbic, G.
A novel methodology for economic evaluation of hydrogen storage for a mixed wind-nuclear power plant is presented in this article in a context of a “hydrogen economy.” The simulation of the operation of the combined nuclear-wind-hydrogen system is discussed first, where the selling and buying of electricity and the selling of excess hydrogen and oxygen is optimized to maximize profits. This simulation is done in two phases: In the pre-dispatch phase, the system operation is optimized according to stochastic wind and price forecasts to obtain optimal hydrogen charge levels for the operational horizon. In the second phase, a real-time dispatch is carried out on an hourly basis to optimize the operation of the system to maximize profits, and to follow the storage levels of the pre-dispatch phase. Based on the operation planning and dispatch results, an economic evaluation is performed to determine the feasibility of the proposed scheme for investment purposes. The results of these studies demonstrate that hydrogen for the sole purpose of storage of electricity is not economically feasible at the current state of hydrogen technology development, unless hydrogen is sold to the market for other purposes such as transportation, as in the case in a hydrogen economy, or in the case of limited electricity transmission capacities, i.e., transmission congestion.
Probabilistic Optimal Power Flow in Electricity Markets Based on a Two-Point Estimate Method
(Institute of Electrical and Electronics Engineers (IEEE), 2006-11-30) Verbic, Gregor; Canizares, Claudio A.
This paper presents an application of a two-point estimate method (2PEM) to account for uncertainties in the optimal power flow (OPF) problem in the context of competitive electricity markets. These uncertainties can be seen as a by-product of the economic pressure that forces market participants to behave in an “unpredictable” manner; hence, probability distributions of locational marginal prices are calculated as a result. Instead of using computationally demanding methods, the proposed approach needs2nruns of the deterministic OPF fornuncertain variables to get the result in terms of the first three moments of the corresponding probability density functions. Another advantage of the 2PEM is that it does not require derivatives of the nonlinear function used in the computation of the probability distributions. The proposed method is tested on a simple three-bus test system and on a more realistic 129-bus test system. Results are compared against more accurate results obtained from MCS. The proposed method demonstrates a high level of accuracy for mean values when compared to the MCS; for standard deviations, the results are better in those cases when the number of uncertain variables is relatively low or when their dispersion is not large.

Browse

Recent Submissions