UNB Scholar Research Repository :: Browsing by Author "Saleh, Saleh"

Browsing by Author "Saleh, Saleh"

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A battery storage system to support the frequency stability of grid-connected PMG-based wind energy conversion systems
(University of New Brunswick, 2019) St-Onge, Xavier F.; Saleh, Saleh
Over the past few decades, the generation of electric power has become concerning for the environment. As a result, several changes to power systems have been introduced. Among these changes, is the significant integration of distributed generation units (DGUs). For, DGUs strive to offset conventional generation by utilizing renewable energy. Largely, this approach to generation has trended toward wind systems. Modern wind-energy-conversion-systems (WECSs) have favored variable speed permanent magnet generator (PMG)-based topologies. The relative novelty of PMG-based WECSs has emphasized challenges that have limited their applicability. Of these challenges, PMG electromechanical torque pulsations and point-of-common coupling (PCC) frequency instability are regularly regarded as the most troublesome. On one hand, PCC frequency variations are dependent on the stable delivery of power by the interconnected WECS. On the other hand, generator torque pulsations are a consequence of the extensive use of power electronic converters (PECs) in PMG-based WECSs. As of late, energy storage systems (ESSs) and novel PEC technologies are being recommended to overcome these challenges. This thesis aims to develop and evaluate a split-bus PMG-based WECS. The developed WECS includes a generator-charged and PCC-discharged battery storage system (BSS) to support PCC frequency stability, as well as a modified cascaded H-bridge (MCHB) generator-side PEC to reduces PMG torque pulsations. The developed system is modeled in simulation and constructed in laboratory. Several operating conditions of wind speed, power command, and BSS charging are investigated. Experimental performance highlights the developed WECS’s ability in suppressing PMG torque pulsations while minimizing PCC frequency variation.
A compact power supply for dielectric barrier discharge devices
(University of New Brunswick, 2016) Allen, Brad; Saleh, Saleh; Colpitts, Bruce
Plasma generation by dielectric barrier discharge (DBD) devices has recently become a topic of interest for researchers due to the growing number of industrial applications. Some applications of note include: generation of ozone gas for disinfecting and cleaning, aerodynamic flow control over an airfoil, light emission for plasma displays and CO2 lasers, and others. The emergence of these new applications, specifically aerodynamic flow control for aeronautical applications, has created significant need for adaptable, compact and lightweight power supplies. The majority of the required high-voltage and high-frequency AC supplies employed by DBD devices have been based on resonant-type power electronic converters (PEC’s). Nonetheless, resonant PEC’s typically are neither small nor lightweight, which make them less desirable for supplying DBD devices in aeronautical applications. In addition, resonant PEC’s are generally not adaptable as their AC outputs are produced over a narrow frequency range, and their operation requires complicated control schemes. In this work, the size and weight requirements of a DBD device for aeronautical applications will be achieved using multi-stage and multi-level switch mode PEC’s. The multi-stage structure will consist of multiple DC-DC step-up PEC’s supplied from batteries. These DC-DC PEC’s will feed a multi-level DC-AC PEC, which will be operated to produce high voltages over a wide range of high frequencies. The DC-DC and DC-AC PEC’s will be operated using switching signals generated by digital signal processing (DSP) platform in order to ensure high quality AC outputs. Moreover, desired switching signals will be generated to facilitate adjusting the magnitude and the frequency of the output AC voltage. Such adjustments will allow manipulation of the DBD body force and/or the plasma velocity, which alters the thrust and/or the boundary layer separation. This work focuses on the design, construction, performance testing, and optimization of the size and weight of a power supply for a DBD device for aeronautical applications. Modeling and simulation tests have been conducted for various operating conditions. An experimental prototype was constructed for performance evaluation of the multi-stage and multi-level power supply, test results are reported and compared to the predictions.
A modular protection for grid-connected battery storage systems
(University of New Brunswick, 2018) McSheffery, Ryan; Saleh, Saleh
Power systems have been showing a growing interest in utilizing different types of energy storage systems (ESSs), which can be operated as interconnected components. Such ESSs are sought to accommodate high penetration levels of renewable energy, peak-demand management, smart grid functions, and energy markets. Battery units, flywheels, compressed gas, pumped hydro, super capacitors, and superconducting magnetic energy storage (SMES) units are among the popular energy storage systems that have shown potential application for interconnected operation. The design and operation of interconnected ESSs, along with improving the power density, have been subjects for several research works, which recommended the use ESSs with electric energy storage for high power applications. These recommended ESSs include battery units, supper capacitors, SMES units, compressed gas and pumped hydro. The majority of recommended ESSs require the use of power electronic converters (PECs) for charge and discharge operation. Nowadays, battery units, super-capacitors, and SMESs are commercially available with a wide range of power and voltage ratings. Despite the remarkable improvements in the efficiency, reliability, and power density of interconnected battery, super-capacitor, and SMES based ESSs, their protection remains a challenge for their host power systems. In the majority of grid-connected ESSs, the protection is designed using current-based and/or voltage-based protective devices. Several research works have been conducted to address the possible impacts of interconnected ESSs on utility-grade protective devices. The outcomes of these research works have suggested that interconnected ESSs can contribute to fault currents, and adversely impact the responses of upstream non-unit protective devices. Furthermore, these research works have recommended featuring the main controllers of interconnected ESSs with faster responses to changing conditions of the ESSs. However, meeting such a recommendation has to consider the controller characteristics, type of fault, maximum input and output currents, and state-ofcharge of protected ESSs. Other approaches have been developed to address the challenges facing protective devices due to interconnecting ESSs, including the directional relays, adaptive coordination, voltage relays, and communication-assisted relays. These approaches have shown some limited performance due to the impacts of PECs and their controllers on the voltage-current behaviors during and post fault conditions. Moreover, the ability of the relays used demonstrated limited capabilities to detect faults involving grid-connected PECs. The main objective of this research is to develop and test a new digital protection scheme for interconnected ESSs. The proposed digital protection will be designed using multiple digital relays that are located in different parts of the protected ESS. The overall response of the proposed digital protection will be set as a combination of responses by digital relays to maintain a reliable power flow to or from the host power system. The proposed digital protection will be tested for an interconnected battery ESS under different operating and fault conditions.
A symmetrical component feature extraction method for fault detection in induction machines
(IEEE, 2019-09) St-Onge, Xavier F.; Cameron, James; Saleh, Saleh; Scheme, Erik J.
Induction motors (IMs) are among the fully developed electromechanical technologies that are still in use today. Over the course of the last century, their structure, control, and operation have been undergone through several stages of development. Among stages of development, the automated control and continuous monitoring of IMs has benefited from the emergence of modern artificial intelligence (AI) methods. IM automation schemes have demonstrated the ability to provide machine fault detection and diagnosis (FDD) function. AI-based FDD methods in IMs have employed frequency-domain, time-frequency, and time-domain analyses as the basis of their feature extraction schemes. A promising feature extraction scheme is one that uses symmetrical components (SCs) in time-domain FDD systems. Current SC-based approaches, however, are limited in their generalizability to different fault classes, may require detailed machine models, and can suffer from computational limitations. In this paper, an improved feature extraction method that uses SCs for a pattern recognition based FDD scheme for three-phase (3φ) IMs will be presented. This novel feature extraction method will be implemented and verified experimentally to demonstrate high classification performance, increased generalizability, and low computational cost.
Features and capabilities of grounding systems in modern power systems
(University of New Brunswick, 2023-04) Jewett, Danielle; Saleh, Saleh
Ground currents and ground potential rise are major causes for thermal damages, degraded performance, poor power quality, and safety risks in power system equipment (generating units, transformers, home appliances, substations, etc.). Transient changes in ground currents and potentials are typically triggered by ground faults (single-line-to-ground and double-line-to-ground faults), as well as steady-state high-harmonic current-flows to system grounding. In many cases, the rapid rise in ground potential during a ground fault, can lead to transient over-voltages and/or phase inversion, which pose significant challenges to the operation of various power system equipment. Adverse impacts of high ground currents and potentials can be reduced by an adequate design of grounding systems. This thesis provides detailed time-domain models of grounding system designs, along with their recommended settings that can ensure stable operation of power system equipment. In addition, this thesis presents performance and comparison results for grounding system designs during and post ground faults.
Impacts of smart grid functions on load-side frequency
(University of New Brunswick, 2019) Wo, Jeffrey W. G; Saleh, Saleh; C.G, Eduardo
Several power systems have made notable progress in implementing smart grid functions as means to achieve load-side control activities. These new control approaches have shown promising potentials to reshape and optimize patterns of energy supply and demand in industrial, commercial, and residential loads. Demand response, peakload management, and direct load control are recognized as smart grid functions that aim to improve the power system efficiency, system reliability, and increase levels of sustainable energy generation and distribution. Several research directions and new business models have been introduced to facilitate and improve the implementation and deployment of smart grid functions in power systems. In general, the fundamental objective of smart grid functions is to regulate the electric power delivered to a set of loads or a set of load centers, where the principal focus is on the active power. Such an objective can introduce new challenges for the operation, control, dynamic conditions, and stability of the host power system. These challenges are centered around the frequency dynamics and margins of frequency stability. As a result, new methods and procedures are sought to carry out accurate assessment of possible impacts from smart grid functions on frequency dynamics and frequency stability margins. The successful development of such methods and procedures will allow setting stable ranges for the load-side control activities, which are associated with smart grid functions. This thesis aims to develop, implement, and test a new method for estimating the frequency changes at load buses that are subject to smart grid functions. The estimation of frequency changes is sought to provide stable ranges for the regulation of load power demands, as carried out by smart grid functions. The developed method is based on utilizing the ZIP model that is capable of providing a relationship between load power demands and frequency changes. Such a relationship can be formulated as a set of nonlinear equations, which can be numerically solved to estimate the frequency changes. The employment of the ZIP model is justified by the implementation of smart grid functions, which require the use of load models. The developed loadmodel based method is implemented for performance evaluation using the Barbados power system, which has 118 buses. The developed method is demonstrated to be accurate, simple, and insensitive to durations and/or magnitudes of power demand changes.
LQR control of dual-active bridge DC-DC power electronic converters
(University of New Brunswick, 2020) Richard, Christian; Saleh, Saleh
Recent trends in power system operation have been constructed to implement controlled and bi-directional power flows on the load side. Such power flows have facilitated the implementation of the load-follows-generation new strategy for operating power systems. In addition, the successful implementation of controlled and bi-directional power flows has supported the integration of different types of distributed generation and storage (DGS) units. These new generation assets are typically interconnected to distribution systems by stages of power electronic converters (PECs). The back-to-back, modular, and solid-state transformers are examples of PEC topologies used to interconnect DGS units. The major functions of PECs in DGS units, include converting, processing, and controlling the electric power to meet certain conditions imposed by the host grid. These conditions mandate the design of controllers to accurately and effectively operate stages of PECs in stable and reliable manners. Among the key PECs to implement controlled and bi-directional power flows are the conventional and resonant dual active bridge (DAB) dc PECs. These bi-directional dc PECs are widely used to construct active DC-links in many applications, such as voltage and reactive power compensation, motor drives, plasma generation units, etc. The employment of DAB dc PECs in power systems requires the design and implementation of accurate, fast, and reliable controllers. This thesis aims to design, implement, and test linear-quadratic regulator (LQR) controllers for the DAB and resonant DAB dc PECs. The design of an LQR controller is achieved by the development of linearized models for the DAB and resonant DAB dc PECs. These models are developed to accommodate the switching scheme, as well as the relationship between the duty cycle and reference voltages. Furthermore, the developed models for DAB and resonant DAB dc PECs are used to devise a tuning procedure for the designed LQR controllers. The performance of the designed LQR controllers is tested for the DAB and the resonant DAB dc PECs under different conditions. Tested conditions include step changes in the power flow, changes in the voltage on the input side of the PEC, and bi-directional power flows. The results of these tests show that designed LQR controllers can operate DAB and resonant DAB dc PECs to adjust input and output voltages during step changes in the power flow, changes in the direction of the power flow, and changes in the voltage. Observed performance features are also compared with other controllers under similar conditions. Test and comparison results demonstrate the efficacy of the designed LQR controllers to operate DAB and resonant DAB dc PECs under different loading and dynamic conditions.
Multi-level AC-DC power electronic converter for applications in PMG-based WECSs
(University of New Brunswick, 2016) Rahman, A B M Saadmaan; Saleh, Saleh
Due to their structural and operational features, permanent magnet generators (PMGs) have gained popularity in wind energy conversion systems (WECSs). The general structure of a PMG-based WECS is composed from a voltage source (VS) ac-dc power electronic converter (PEC)(generator-side PEC), which feeds a VS dc-ac PEC (grid-side PEC) that delivers both active and reactive powers to a grid and/or a load. Such a structure (usually called a back-to-back PEC WECS) offers an independent control of both PECs to accommodate variable wind speed operation. Despite the flexible control, back-to-back PEC PMG-based WECSs suffer a disadvantage due to the current harmonics generated on inputs of the generator-side PEC. These current harmonics create distortions in the stator magnetic field of PMG, and cause pulsations in the electromagnetic torque. The pulsations in electromagnetic torque of a PMG can lead to several undesired operating conditions, including sustained mechanical vibrations in the wind turbine tower, damages to the turbine shaft and rotor mechanical assembly, wear-outs of mechanical fittings of the PMG and turbine couplings, and difficulties in realizing the maximum power point tracking (MPPT) operation. This research aims to investigate the possibility of reducing the pulsations in the electromagnetic torque of a PMG, when used in back-to-back PEC WECSs. The proposed approach is based on employing a 3ɸ, multi-level, VS, ac-dc PEC as the generator-side PEC. The ability of multi-level ac-dc PECs to reduce current harmonics on their inputs will be employed for achieving the objectives of this research.
Non-intrusive load modeling using Newton-phaselet frames
(University of New Brunswick, 2015) Pijnenburg, Petrus; Saleh, Saleh
Power system companies, including Canadian ones, have been making remarkable efforts towards implementing smart grid functions within their service domains. These efforts are spearheaded by establishing demand response programs for residential and small commercial loads (RSCLs). Demand response programs face a major challenge in their capacities to offer effective and economic options for customers in RSCLs, and thus fail to attract wide customer participation. The major challenge facing demand response programs is the lack of accurate models for energy demands and patterns of consumption in RSCLs. Available models of RSCLs are based on statistical methods, which require collecting significant amounts of data for energy demands of RSCLs over different hours each season. Statistical methods generally produce approximate models that may not accurately represent energy demands and patterns of consumption in RSCLs over different seasons. Furthermore, data collection from RSCLs can raise the costs of implementing smart grid functions, as extra instrumentation is required to monitor and record energy consumption of RSCLs. The main objective of this research is to develop new models for RSCLs using numerical methods and orthogonal multi-frames. The proposed modeling method uses one value of the active power P to calculate one value of the apparent power | ¯ S|, while it employs six phaselet frames to calculate a value of the angle θ (the phase of ¯ S). Calculated | ¯ S| and θ are used to calculate a value of the active power Pc, which is compared to P in order to adjust | ¯ S| for the next Newton iteration. Calculated values of Pc, | ¯ S|, and θ at each iteration are employed to determine a value of the reactive power Q at the same iteration. Determined values for Pc, | ¯ S|, θ, and Q, for each value of P, are employed to complete the constant impedance (Z), constant current (I) and constant power (P) modeling, commonly called the ZIP model, for RSCLs. In these loads, changes in the voltage, due to ON-OFF switching, are assumed negligible, where constant power and constant current loads become of a similar class in the ZIP model. The complete ZIP model has standardized parameters for the power consumption in each appliance, and thus the ON-OFF status of each appliance can be determined using its standardized parameter. This approach is implemented as an algorithm, and realized for performance evaluation using different sets of collected power measurements. Performance results show simple implementation, accurate determination of ON-OFF status, and a low memory requirement.
Novel control for small-scale three-phase wind generation systems in high wind speed regions
(University of New Brunswick, 2020) Song, Guanhong; Chang, Liuchen; Saleh, Saleh
This Ph.D. research focuses on control methods for performance improvement for small-scale three-phase wind generation systems particularly when operating in high wind speed regions. For small-scale wind generation systems, the generated torque and power as well as the rotation speed fluctuate violently with changing wind conditions. And these fluctuations would easily result in over-rated operation. Many attempts in regulating the system have been presented in recent literature which can be summarized by adding additional regulation devices, such as: pitch control units, yaw control units; and by advanced control algorithms. The additional regulation components will lead to an increase in system cost and size which make the use of the advanced control algorithm more promising in the practical applications. In order to overcome the drawbacks of the control methods in recent literature, a novel control algorithm called “High Wind Power Regulator (HWPR)” is designed as a major part of this dissertation to perform electrical stall regulation of the small-scale wind generation system when operating in high wind speed regions. Meanwhile, in a typical wind generation system, a DC-link is used to balance the power difference and to decouple the control between the wind generator-side converter and the grid-side inverter, which plays a critical part in the system. However, as the HWPR algorithm regulates the wind generation system in high wind speed regions, the power flow from the wind generator to the power grid changes violently due to rapid wind power changes. And this rapid power transition may cause severe DC-link voltage fluctuations. In order to reduce this DC-link voltage fluctuation, observer-based DC-link voltage control algorithms featured in fast DC-link voltage regulation are also developed in this Ph.D. research. The proposed algorithms estimate the power value fed into the DC-link and integrates with a Proportional-Integral (PI) controller combining the advantages of a fast-transient response offered by the observer and control robustness from the PI controller. The effectiveness of the proposed control methods for small-scale wind generation have been verified through both the computer simulation on a MATLAB/SIMULINK platform and laboratory experiments on a wind turbine testbed with a prototype wind generation system.
The development of survivability analysis for power systems
(University of New Brunswick, 2021) Chowdhury, Muhammad Rashedul Alam; Saleh, Saleh
The structural and operational natures of power systems make these systems prone to experience various types of transient events. Such undesired events include the loss of generation units, loss of transmission lines, load rejections, sudden and abrupt changes in load power demands, equipment failures, etc. The impacts of transient events start by creating frequency dynamics that can disrupt the generation, transmission and distribution of electric power in any power system. The conventional approaches to mitigate and damp frequency dynamics are set to restore the balance between power generation and demands so that a power system can regain a steadystate condition post any transient event. In general, the conventional approaches are usually designed and operated based on power system dynamics and stability analyses. These analyses are conducted with the assumption that frequency dynamics can be responded to by actions initiated by primary, secondary, or tertiary frequency controllers. The dynamics and stability analyses of power systems are widely used to design power system stabilizers, operate frequency controllers, and select settings for protective device. Conventional responses to frequency dynamics restore the balance between power generation and demands by either adjusting power generation (governor control), changing inter-area power exchange, or disconnecting loads. Such responses have shown a good capacity to effectively damp frequency dynamics and regain steadystate conditions in power systems. However, the recent trends of operating power systems have been shifting towards the de-regulated operation, which can offer integrating distributed generation units and deploy load-side control actions. Despite its advantages, the de-regulated operation of power systems faces several challenges, including the frequency dynamics. This challenge is created by the bi-directional power flows of load buses, as well as load-side control actions that may alter the active power injection into load buses. Frequency dynamics created by such activities can be difficult to damp using conventional responses. This difficulty is due to the fact that the disconnection of loads can (as a response) worsen the frequency dynamics. As a result, new responses are mandated to damp frequency dynamics created by load-side control activities. This thesis develops and tests a survivability-based method to model and analyze the impacts of load-side activities on frequency dynamics in power systems. The developed method introduces a survivability index to quantify the ability of a load bus to regain a steady-state condition, after experiencing a load-side activity. The survivability index is defined as the difference between pre-activity and post-activity power injection into a load bus. The boundary values of the survivability index are also defined in this thesis, and they are used to specify energy storage systems to enhance the survivability of certain load buses. The survivability-based method is implemented as a stand-alone software tool, and is being used by Barbados Power System. Several tests are conducted for integrating solar units and implementing demand response at several load buses. Test results show that the survivability index can accurately quantify the ability of load buses to regain steady-state conditions, and damp frequency dynamics created by load-side activities. Moreover, the survivability index is used to specify battery storage units for load buses with narrow survivability margins. Finally, test results demonstrate that the validity and accuracy of the survivability-based method is not affected by the ratings of integrated solar units and/or times and durations of demand response actions.

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