Geza Joos

Geza Joos
McGill University | McGill · Department of Electrical & Computer Engineering

About

417
Publications
64,941
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
15,983
Citations
Additional affiliations
September 2001 - December 2011
McGill University
January 1988 - December 2004
Concordia University
January 1978 - September 1988

Publications

Publications (417)
Preprint
Full-text available
The reduced inertia in power system introduces more operation risks and challenges to frequency regulation. The existing virtual inertia and frequency support control are restricted by the normally non-dispatchable energy resources behind the power electronic converters. In this letter, an improved virtual synchronous machine (VSM) control based on...
Preprint
Full-text available
Thermostatically-controlled loads have a significant impact on electricity demand after service is restored following an outage, a phenomenon known as cold load pick-up (CLPU). Active management of CLPU is becoming an essential tool for distribution system operators who seek to defer network upgrades and speed up post-outage customer restoration. O...
Article
Full-text available
Dependence on the depleting fossil fuels, particularly in the transportation sector, calls for sustainable, green solutions such as electrification, which address the challenges of providing alternate sources of power at low emissions. Electric vehicles (EVs) are the centerpiece of the transportation electrification sector. Reducing the time for ch...
Article
Full-text available
Electric vehicle (EV) is commonly considered as an electric load in a residential energy network. However, the large capacity EV battery can be used as electric storage when the EV is plugged in at home. While model predictive control (MPC) offers an efficient and reliable control mechanism for a home energy management system (HEMS), the uncertaint...
Article
Forced oscillations may jeopardize the secure operation of power systems. To mitigate forced oscillations, locating the sources is critical. In this paper, leveraging on Sparse Identification of Nonlinear Dynamics (SINDy), an online purely data-driven method to locate the forced oscillation is developed. Validations in all simulated cases (in the W...
Preprint
Forced oscillations may jeopardize the secure operation of power systems. To mitigate forced oscillations, locating the sources is critical. In this paper, leveraging on Sparse Identification of Nonlinear Dynamics (SINDy), an online purely data-driven method to locate the forced oscillation is developed. Validations in all simulated cases (in the W...
Preprint
Low inertia, nonlinearity and a high level of uncertainty (varying topologies and operating conditions) pose challenges to microgrid (MG) systemwide operation. This paper proposes an online adaptive Koopman operator optimal control (AKOOC) method for MG secondary voltage and frequency control. Unlike typical data-driven methods that are data-hungry...
Article
In this paper, we apply flexibility-based operational planning method to microgrid (MG) unit commitment (UC). The problem is formulated based on model predictive control (MPC) paradigm. Conventionally, such paradigm requires the online solution of a mixed-integer optimization problem, which faces difficulties in practical field implementations in a...
Chapter
Integrated battery chargers (IBCs) have been proposed as a low-weight, low-volume, and high-power solution to conventional conductive chargers. However, the design of such chargers is complicated, requiring special components or control techniques to solve inherent issues (such as galvanic isolation, torque generation, and system reconfiguration) a...
Article
Low inertia, nonlinearity and a high level of uncertainty (varying topologies and operating conditions) pose challenges to microgrid (MG) systemwide operation. This paper proposes an online adaptive Koopman operator optimal control (AKOOC) method for MG secondary voltage and frequency control. Unlike typical data-driven methods that are data-hungry...
Article
Full-text available
The reduced inertia in power system introduces more operation risks and challenges due to the degraded frequency performance. The existing virtual inertia control and fast frequency response to tackle this issue are restricted by the energy resource behind the power converter. In this paper, an improved virtual synchronous machine control is propos...
Preprint
Full-text available
Building energy management is one of the core problems in modern power grids to reduce energy consumption while ensuring occupants' comfort. However, the building energy management system (BEMS) is now facing more challenges and uncertainties with the increasing penetration of renewables and complicated interactions between humans and buildings. Cl...
Article
In this paper, we apply a flexibility based operational planning paradigm to microgrid energy dispatch. The classic energy dispatch problem with energy storage and dispatchable thermal generation assets requires the solution of mixed-integer optimization problems. Such approaches are not amenable to most remote microgrids and practical field microg...
Article
Full-text available
With reference to the newly released microgrid standards, design and real-time implementation of a centralized microgrid control system is presented in this paper. In grid-connected mode, the utility grid will provide the voltage and frequency reference at the point of connection. The assets within the microgrid will follow power command references...
Article
The deepening penetration of renewable power generation is challenging how the minute balancing of supply and demand is carried out by power system operators. Several proposals to short-term operational planning rely on robust optimization to offer guarantees on the ability of the operator to meet a wide array of possible scenarios. The main downsi...
Preprint
Full-text available
A DER management system (DERMS) is proposed for aggregating discretely and continuously controlled DERs in microgrid and distributing power among them based on weighted and queuing (W&Q) algorithm.
Conference Paper
Full-text available
The use of distributed control systems for microgrid control has gained traction in recent years for their reliability and modularity. As part of microgrid control core functions, islanding is implemented to enhance power supply reliability during outages. This paper proposes a distributed multi-agent control system architecture for the management...
Article
This paper presents a new method of instability detection and subsequent stabilization of the power system network using a proposed multi-shot Remedial Action Scheme (RAS) that can extemporaneously detect critical generators based on the dynamic states of generator computed from the terminal Phasor Measurement Units. The instability detector is a m...
Article
Full-text available
The low‐frequency dynamics of virtual synchronous machine (VSM) depends on multiple factors. In this study, the oscillation mode of a single VSM is first identified by exploring the evolution of oscillation from synchronous mode to sub‐synchronous mode with the variation of structure and parameters. The inter‐oscillation modes among multiple VSMs m...
Article
Full-text available
Isochronous controlled battery energy storage system (ESS) can maintain constant frequency in islanded AC microgrid, but its power and state of charge (SoC) may go beyond limit due to intermittent renewable energy resources and impact load change. This paper introduces a control strategy integrated with bang-bang and backlash mechanism to coordinat...
Conference Paper
Full-text available
Power distribution systems require continuous monitoring as the integration of renewable energy resources is increasing and the load demand is growing. The implementation of synchrophasors in distribution systems enhances the situational awareness of the system and provides a unique opportunity for developing new monitoring algorithms. This paper p...
Conference Paper
The challenge of microgrid protection is associated with many factors, such as frequently changing conditions and topology, lack of established power flow direction, presence of inverter-interfaced generation, among others. To overcome the challenges faced by the conventional protection, the paper demonstrates the application of a synchrophasor-bas...
Conference Paper
In this paper, phasor measurements taken from stator and rotor terminals are used for dynamic state estimation of a doubly fed induction generator (DFIG) assuming a reduced order model (3rdorder) with unknown mechanical input torque. The proposed estimator provides the advantage that the converter and associated controller dynamics as well as turbi...
Article
Full-text available
The paper proposes a torque cancellation strategy for a non-isolated three-phase integrated battery charger (IBC) topology for light and medium duty EV drives based on six-phase permanent magnet (PM) synchronous machines. The charger requires a three-phase grid interface and utilizes the machine windings as the input filter inductances after minor...
Article
An improved dynamic state estimation scheme that performs estimation for the full plant, (states of generator, exciter field voltage and governor mechanical torque) using intermittent data from phasor measurement unit (PMU) connected at generator terminal is presented. Overall fourth order generator model is assumed in Extended-Kalman Filter (EKF)...
Article
Direct methods have been a promising development for decades, receiving however less attention recently. One of the reasons is the limited capacity to include more realistic models of the power systems equipment. This paper derives a structure-preserving analytical energy function for a 6th order synchronous generator model with subtransient dynami...
Article
This paper proposes a hierarchical decision making model for a coupled planning and operation problem of an advanced microgrid. The proposed model, is formulated as a bilevel optimization problem and recast as a mathematical program with equilibrium constraints (MPEC) where the decision variables of the two problems are independently controlled. Th...
Article
Microgrids are receiving increasing attention from power systems planners as a means to integrate distributed energy resources (DER) including renewable energy resources into the grid, and as a means of balancing the variability of renewable resources and loads with flexible generation. A key to justifying microgrids is establishing their business...
Conference Paper
A study of effect of parametric variability on dynamic state estimates of synchronous generator operating using terminal Phasor Measurement Unit has been conducted. Parametric variations have been modelled using Monte Carlo method and state deviation from actual ones has been presented using suitable metrics. In addition impact of individual parame...
Conference Paper
Accelerated developments of renewable energy production technologies and their integration to existing AC microgrids have led to the emergence of several new inverters control schemes. The recently introduced proportional resonant (PR) controllers have the ability to precisely track AC quantities and are increasingly used in grid supporting inverte...
Article
Full-text available
Compared with multilevel space vector modulation (SVM), level-shifted multicarrier sinusoidal pulse width modulation (SPWM) for NNPC inverters requires much less calculations and implementation efforts, but the existing conventional SPWM cannot suppress the severe flying-capacitor voltage ripples under low output-frequency conditions. In order to s...
Article
This paper proposes a bi-level formulation for a coupled microgrid power and reserve capacity planning problem, cast within the jurisdiction of a distribution system operator(DSO). The upper level problem of the proposed bi-level model represents a microgrid planner whose goal is to minimize its planning and operational cost, while the lower level...
Article
Full-text available
The study proposes a non-isolated three-phase integrated battery charger (IBC) based on electric vehicle drivetrains that have two permanent magnet synchronous motors with shafts coupled via a torque coupler. The windings of both machines are used as input filter inductances after reconfiguration and connected to a three-phase grid in charging mode...
Article
The output current ripple of an inverter shows different variations for sub-fundamental operating cycle and over few fundamental cycles. This paper investigates sub-fundamental cycle peak-peak current ripple variation of a three-level three-phase inverter over the entire operating modulation index range for the three-level continuous and discontinu...
Article
This paper proposes a method to vary the switching frequency within a fundamental cycle to reduce the switching losses of a two-level inverter while maintaining the peak-peak current ripple within a predefined limit. Unlike conventional strategies, the proposed technique utilizes pre-computed switching frequency variation factors without relying on...
Article
The increasing penetration level of renewable energy brings new challenges to the field of islanding detection. In this study, a decision-tree (DT)-learning method with hardware-in-the-loop (HIL) simulations is proposed to address the non-detection zone (NDZ) issue of islanding detection in hybrid distributed generation systems including both inver...
Chapter
The use of advanced technologies has made it possible to transform the power grid to an intelligent smart grid with real time control and monitoring of the system. The development of Phasor Measurement Units (PMUs) and the resulting possibility of real time measurements has enabled different power system applications to enhance the stability, state...
Article
This paper investigates and proposes a mitigation strategy for Denial-of-Service (DoS) cyber-attacks, targeting the most critical distributed energy resource (DER) in an islanded microgrid featuring a high penetration of renewables; the energy storage system (ESS) operating as the isochronous generator that forms and regulates the microgrid voltage...
Article
Conventional three-level discontinuous pulse-width modulation (DPWM) templates typically provide maximum switching loss reduction capability for load power factor angles in the range from 30° lagging to 30° leading. This paper proposes three space-vector based DPWM templates for lower power factors and a generalized DPWM strategy for three-level in...
Article
Micro-grid (MG) monitoring and information sharing between them through a central monitoring unit is required in the present day operational environment. The proposed research focuses on developing wide-area monitoring platform for multiple MGs running in parallel. This is achieved by using C37.118.1 complied phasor measurements units (PMUs) which...
Conference Paper
This paper investigates cyber-attacks compromising the data integrity of inverter-based islanded microgrids featuring an energy storage system (ESS), a wind turbine generator (WTG), a photovoltaic system (PV) and controllable loads. The ESS operates as the isochronous generator, responsible for forming the microgrid voltage and frequency, whereas t...
Article
This paper presents a formulation to determine the appropriate power dispatch of an energy storage system, whose available energy is dependent on the charging/discharging pattern from previous time periods. The implementation structure is consistent with current dispatch algorithms used in microgrids, and the algorithm can be used in either grid-co...
Conference Paper
This paper proposes the real-time implementation of an energy management system (EMS) optimization sequence and enumerates a set of performance metrics for grid-connected microgrids. The operation and performance of the proposed microgrid EMS is validated using a real-time hardware-in-the-loop (HIL) testing platform. The test system emulates the mi...
Conference Paper
This paper proposes a topology for the combined frequency/oscillation damping active power control loop for type 4 wind turbines. In order to assess the effects of standard transient network frequency support control loops and the established controller topology on frequency response a quasi steady-state frequency model for the wind turbine equippe...
Article
This paper proposes a dual three-level, T-type, neutral-point clamped (T-NPC) inverter fed dual permanent magnet synchronous motor topology for low-voltage, high-power traction applications. The switching pulses of the T-NPC inverters are interleaved and controlled, such that they produce equal and opposite three-phase currents at their output. Thi...
Article
This study proposes a methodology based on multivariate analysis and data mining techniques that credibly captures the signature of the DG-islanding phenomenon under adverse operating conditions and network faults. This methodology produces decision trees which determine the tripping logic, protection handles and thresholds for each DG-islanding re...
Conference Paper
The high renewable energy penetration level in distribution systems has resulted in an increasing number of inverter-based distributed generators (DGs). Therefore a sophisticated DG interconnection protection relay is required to protect the DGs, overcome the challenges that inverters introduce and respect the new grid requirements. This paper prop...
Article
Many benefits can be achieved through the implementation of a Microgrid controller, such as minimized cost, reduction in peak power, power smoothing, greenhouse gas emission reduction, and increased reliability of service. However, most Microgrid controllers found in the literature and in the industry optimize a single objective, which either exace...
Conference Paper
Full-text available
Battery chargers for plugin electric vehicles can be costly and add to the weight and volume of the vehicle when designed to be on-board. Conversely, integrated battery chargers not only re-use the already available components on-board but also provide a higher charging power capability than their dedicated counterparts. Such chargers use the tract...
Article
Full-text available
This paper proposes a quasi-steady-state modeling approach for an approximation of long-term frequency dynamics in power systems. A specific phenomenon of concern is an onset of frequency swings during load/generation imbalance scenarios. The effects of system voltage characteristics, system inertia, and, more importantly, damping controllers are e...
Conference Paper
The emergence of new distribution-feeder connected power plants, comprised of either synchronous or power electronic interfaced generation, is linked to numerous technical impacts relating to protection and control, power quality, amongst other concerns. Contemporary installations also employ advanced communication protocols such as that defined pe...
Conference Paper
This paper reports on the work of the CIGRE C6.22 Working Group, Microgrid Evolution Roadmap, which has recently finalized its first Technical Brochure. The Working Group was asked to identify the main elements required to justify, develop, and implement viable microgrids, which the Group defined as follows: Microgrids are electricity distribution...
Article
Full-text available
Multi-band power system stabilisers (MB-PSSs) PSS4B (IEEE standard 421.5-2005) are advanced power system damping controllers that have evident advantages over conventional PSSs in damping low-frequency oscillatory modes. However, finding optimal settings for such controllers is challenging due to the increased complexity of the PSS4B structure. Thi...
Article
Optimized PWM techniques have been developed and used with good results for voltage source inverters. However, implementation frequently requires complex electronic circuits, usually microprocessor-based, that cannot be justified in low cost applications. The paper examines three phase PWM pattern generators that are simple to implement with low co...
Article
The paper deals with developing and testing frequency- adaptive PMU algorithms with wider linearity range than specified in IEEE Std C37.118-1. This goal is achieved by means of three different concepts encompassing robust state-of-the-art design approaches: 1) FIR bandpass filtering, 2) extended Kalman filtering (EKF), and 3) discrete Fourier tran...
Article
For the first time, IEEE Std. C37.118.1-2011 now provides metrics for PMU dynamic performance in terms of classes P and M filter designs. This paper attempts to determine whether fulfilling these requirements makes the PMU inherently well suited for stability control applications such as wide-area power system stabilizers (PSSs). In this aim, we co...
Article
In all areas of engineering, modelers are constantly pushing for more accurate models and their goal is generally achieved with increasingly complex, data-mining-based black-box models. On the other hand, model users which include policy makers and systems operators tend to favor transparent, interpretable models not only for predictive decision-ma...
Conference Paper
Full-text available
A differential energy based fault protection in microgrid is presented in this paper. Initially the currents at the respective buses are retrieved and processed through a novel time-frequency transform known as S-transform to generate time-frequency contours. Spectral energy content of the time-frequency contours of fault current signals are calcul...
Article
Full-text available
This paper presents a new approach for fault detection and classification in transmission line using Decision Tree (DT). The DT based fault detection algorithm uses 1/4th cycle data of fault currents from fault inception, to generate the optimal decision tree for fault detection. Similarly, the DT based classification algorithm takes half cycle dat...
Conference Paper
The purpose of this paper is to demonstrate the effects of implementing different ESS sizes in wind-diesel micro-grids based on various wind penetration values. By performing parametric analyses, it can be shown which wind power penetration levels an ESS would be best suited. The three parameters that are varied in this analysis include: the wind p...
Article
Full-text available
The current paper focuses on the energy management in a fast charging station for PHEV batteries; that uses in addition to the grid a flywheel energy storage and a supercapacitor; with main objective to minimize the duration of the battery charging process and the time required to recharge the storage devices afterward. The designed station is capa...
Article
The steady-state performance of phasor measurement units (PMUs) is well standardized in the recently issued revised IEEE Std. C37.118. The Western Electricity Coordinating Council (WECC) has developed dynamic performance requirements for PMU filters as a means to guarantee better, uniform PMU response under dynamic conditions, such as power swings...
Article
Full-text available
The design and simulation of a fast-charging station in steady-state for PHEV batteries has been proposed, which uses the electrical grid as well as two stationary energy storage devices as energy sources to recharge the PHEV battery. The two energy storage devices comprising the fast-charging station are a supercapacitor and a flywheel energy stor...
Article
A knowledge-based expert system (KBES) is proposed for the scheduling of an energy storage system (ESS) installed in a wind-diesel isolated power system. The program optimises the cost of operation by determining the diesel generation and the charging/discharging cycles of the storage system from the wind and load profiles one hour in advance. The...
Article
Critical to real-time oscillations monitoring is early detection when otherwise dormant natural modes become a serious threat to grid stability. The next urgent issue is to determine the frequency and damping of the problematic modes when the signal is embedded in noise and the system contains closely spaced natural modes. The present paper address...
Article
Energy storage systems (ESSs) can be applied to mitigate some of the negative impacts associated with a variable power generation source such as wind energy. The control of ESS power must be accomplished over numerous time frames to meet system objectives and respect ESS capacity constraints. This paper proposes a two-level ESS control structure fo...
Article
Full-text available
This study proposes ensemble decision trees for phasor measurement units (PMUs)-based wide-area security assessment to provide early warnings of deteriorating system conditions. In the proposed technique, the wide-area response signals in real-time operation are captured after 1 and 2 s fault clearing time, from the respective monitoring buses wher...