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Ilamparithi T.,Opal - RT Technologies | Nandi S.,University of Victoria | Subramanian J.,University of Victoria
IEEE Transactions on Industry Applications | Year: 2015

A novel scheme to reliably monitor the condition of static and dynamic eccentricity (DE) faults in salient-pole synchronous machines (SPSMs) through the standard short-circuit test is proposed in this paper. The detection technique is based on offline current signature analysis that does not require machine disassembly. The procedure is unaffected by machine saturation or supply voltage harmonics. In this scheme, DE fault is monitored by exploiting the presence of inherent static eccentricity (SE), whereas SE fault monitoring is achieved using residual estimation technique. The proposed method is found to work for both star and delta-connected machines. Results obtained from an experimental three-phase 2-kW SPSM have been used to validate the proposed eccentricity condition monitoring method. © 1972-2012 IEEE.


Saad H.,Ecole Polytechnique de Montréal | Ould-Bachir T.,Ecole Polytechnique de Montréal | Mahseredjian J.,Ecole Polytechnique de Montréal | Dufour C.,Opal - RT Technologies | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2015

Modular multilevel converter (MMC) structures are composed of several hundreds to thousands of half-bridge converters. Such large numbers of power switches and electrical nodes introduce important numerical challenges for the computation of electromagnetic transients. The problem becomes particularly more complex for the real-time simulations. This paper presents a feasibility study on the real-time simulation of the MMC models. CPU-based and field-programmable gate array-based implementations are proposed and evaluated for the MMCs having up to 401 levels. The study also provides guidelines for the real-time simulation platform requirements to simulate these MMC models. © 1986-2012 IEEE.


Ilamparithi T.,Opal - RT Technologies | Nandi S.,University of Victoria
Proceedings - 2013 9th IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics and Drives, SDEMPED 2013 | Year: 2013

This paper proposes a novel scheme based on current signature analysis to estimate the severity of dynamic eccentricity fault independent of saturation in salient-pole synchronous machines (SPSM). The detection technique uses short circuit test data and exploits the presence of inherent static eccentricity in a machine. Implementation of the scheme involves two steps. First, the percentage increases in both mixed eccentricity component and static eccentricity component are computed. Then the difference between them is used as a factor to estimate the severity of dynamic eccentricity. The method is also found capable of distinguishing between static and dynamic eccentricity faults. Results obtained from an experimental 3 phase, 2.2 kW machine have been used to validate the proposed eccentricity severity estimation scheme. © 2013 IEEE.


Zhang F.,McGill University | Li W.,Opal - RT Technologies | Joos G.,McGill University
IEEE Transactions on Industrial Electronics | Year: 2016

In this paper, an improved model predictive control (MPC) of the modular multilevel converter (MMC) with reduced computational burden is proposed. A mathematical model of the MMC system based on the sum and difference of arm voltages are derived. Instead of determining the switching state of individual submodule (SM), the voltage levels of MMC are considered as control options based on the assumption that the SM capacitor voltages are well balanced. The further reduction of calculation effort is realized by using the tolerance band of capacitor voltages. The proposed MPC has a hierarchical structure. The cost function taking into account the ac-side current control, circulating current elimination and arm energy balancing is presented. The optimal voltage level, selected by the cost function, provides the voltage reference for the pulse width modulation modulator. The SM capacitor voltage balancing is done using a separate control loop. The proposed control strategy is investigated using an MMC high-voltage direct current system with 200 SMs in each arm in real-time simulation and hardware-in-the-loop tests. The performance of proposed method is verified by both steady-state and transient-state operations. © 2016 IEEE.


Li W.,McGill University | Joos G.,McGill University | Belanger J.,Opal - RT Technologies
IEEE Transactions on Industrial Electronics | Year: 2010

Wind power generation studies of slow phenomena using a detailed model can be difficult to perform with a conventional offline simulation program. Due to the computational power and high-speed input and output, a real-time simulator is capable of conducting repetitive simulations of wind profiles in a short time with detailed models of critical components and allows testing of prototype controllers through hardware-in-the-loop (HIL). This paper discusses methods to overcome the challenges of real-time simulation of wind systems, characterized by their complexity and high-frequency switching. A hybrid flow-battery supercapacitor energy storage system (ESS), coupled in a wind turbine generator to smooth wind power, is studied by real-time HIL simulation. The prototype controller is embedded in one real-time simulator, while the rest of the system is implemented in another independent simulator. The simulation results of the detailed wind system model show that the hybrid ESS has a lower battery cost, higher battery longevity, and improved overall efficiency over its reference ESS. © 2010 IEEE.


Dufour C.,Opal - RT Technologies | Belanger J.,Opal - RT Technologies
IEEE Transactions on Industry Applications | Year: 2014

This paper discusses the various aspects involving the research and development of smart grids. Discussed are applications, from large grid renewable integration, wide-area monitoring, protection, and control systems to microgrids. Load scheduling and power balance, communications issues, understanding customer behavior, large-area protection, and distribution control are only some aspects of the challenge of making power grids more robust and more intelligent. The potential complexity of such smart grids requires careful study and analysis before actual realization. This paper explains how such challenges are addressed using real-time simulation technologies in different laboratories around the world. © 1972-2012 IEEE.


Dufour C.,Opal - RT Technologies | Mahseredjian J.,Ecole Polytechnique de Montréal | Belanger J.,Opal - RT Technologies
IEEE Transactions on Power Delivery | Year: 2011

This paper presents a new solution method that combines state-space and nodal analysis for the simulation of electrical systems. The presented flexible clustering of state-space-described electrical subsystems into a nodal method offers several advantages for the efficient solution of switched networks, nonlinear functions, and for interfacing with nodal model equations. This paper extends the concept of discrete companion branch equivalent of the nodal approach to state-space described systems and enables natural coupling between them. The presented solution method is simultaneous and enables benefitting from the advantages of two different modeling approaches normally exclusive from one another. © 2010 IEEE.


Li W.,Opal - RT Technologies | Belanger J.,Opal - RT Technologies
IEEE Transactions on Power Delivery | Year: 2016

In China, two modular multilevel converter (MMC) projects were recently commissioned, and another two are currently under construction. The real-time hardware-in-The-loop (HIL) test bench played an important role in validating the manufacturer's controllers. The full detail MMC model does not fit with the HIL test bench, which has to solve the circuit containing numerous switches and handles a large amount of inputs and outputs at a small time step for real-time simulation. The main challenge is to find a method to model and simulate the MMC systems with sufficient detail, accuracy, and speed. This paper presents an equivalent circuit method for the HIL test bench. The circuit inside the submodule is represented by mathematical equations, implemented in CPU or a field-programmable gate array, and solved in parallel to achieve real-time performance. This method-based test bench is used in those MMC projects in China and connected to the manufacturer's controllers for HIL tests. The model accuracy and simulation speed achieved by this method met the requirements of the HIL tests. In this paper, various scenarios are tested in an MMC HVDC study system. The results achieved by the proposed method have high agreement with those of a reference model in EMTP-RV. © 1986-2012 IEEE.


Li W.,Opal - RT Technologies
IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society | Year: 2015

Industrial modular multilevel converter (MMC) controllers usually implement the sub-module (SM) capacitor voltage balance control (VBC) in field-programmable gate array (FPGA) boards. Conventional VBC methods need to sort out the capacitor voltages, where the sorting algorithm would become too complex to be accommodated in FPGA if the SM number is large. A sorting-less VBC optimized for FPGA implementation is proposed and validated for half-bridge MMC in previous works. This paper continues the work and proposes a compatible VBC FPGA implementation for both half-bridge and full-bridge topologies. The proposed VBC is implemented in an FPGA based real time simulator and investigated in a full-bridge MMC STATCOM test system. The VBC for large MMC (1024 SM per valve) can be implemented in one Virtex 7 FGPA board with an execution cycle time of 250 nanoseconds. The performance is validated in steady states, transients, and fault conditions. © 2015 IEEE.


Ghahremani E.,Opal - RT Technologies | Kamwa I.,Hydro - Quebec
IET Generation, Transmission and Distribution | Year: 2014

Hydro-Québec's electrical transmission system is an extensive, international grid located in Québec, Canada with extensions into the northeastern United States of America. For large power systems such as this, one of the major issues is to maintain the steady-state performance of the network. From this point of view, flexible AC transmission system (FACTS) devices could be effective tools to improve power system security by reducing the power flow on overloaded lines, which in turn would result in an increased loadability of the power system, reduced transmission line losses, improved stability and security and, ultimately, a more energy-efficient transmission system. Therefore in this study, the authors will present the effects of different types of FACTS devices on the performance of Hydro-Québec's power system. The optimal locations and rating of these FACTS controllers will be determined with a view to improving network security using an optimisation algorithm based on a genetic algorithm. The effects of six different FACTS devices including static VAR compensator (SVC), thyristor-controlled series capacitor (TCSC), thyristor-controlled voltage regulator (TCVR), thyristor-controlled phaseshifting transformer (TCPST), unified power flow controller (UPFC) and static synchronous compensator (STATCOM) with energy storage are compared. Using the presented results, the effects of different types of FACTS devices on the Hydro-Québec network will be analysed and compared with those of a STATCOM equipped with energy storage from the viewpoints of static loadability and losses. © The Institution of Engineering and Technology 2014.

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