Xiaodong Liang

• Doctor of Philosophy
• Professor (Full) and Canada Research Chair at University of Saskatchewan

In this article, a novel adaptive critic learning (ACL) framework is constructed for a class of nonzero-sum (NZS) differential games problem of unknown continuous-time (CT) nonlinear systems with state constraints. First, generalized fuzzy hyperbolic model (GFHM)-based identifiers are established to reconstruct the unknown system dynamics. Then, un...

The loss of field (LOF) is a common phenomenon that occurs in the excitation system of a synchronous generator (SG), and the LOF relay (ANSI code 40) offers crucial LOF protections for SGs in electrical power plants. Conventional LOF relays employ one or two offset Mho elements and exploit measured impedance in the generator terminal to detect LOF...

Solar photovoltaic (PV) is a dominant form of renewable energy source and has been widely deployed, but increasing PV power integrated into electric power grids creates challenges in the planning and operation of power grids due to PV power’s intermittency and variability nature. Accurate solar PV power generation prediction techniques are essentia...

Solar photovoltaic (PV) systems can provide reactive power support through their interfacing smart inverters. This reactive power exchange can provide effective voltage regulation at the inverter’s connection point and supplement the voltage regulation already offered by legacy voltage regulation devices, on-load tap changers and capacitor banks. C...

With increasing penetration of renewable energy sources and electric vehicles (EVs) in power grids, developing appropriate models for power system planning is of great importance. This article proposes a novel gray wolf optimization (GWO) algorithm-based transmission expansion planning (TEP) method considering renewable energy sources and EVs and e...

This paper proposes a novel two-stage stochastic Conservation Voltage Reduction (CVR) technique in integrated electricity and natural gas systems, where the mixed-integer second-order cone programming (MISOCP) model is used to coordinate legacy voltage regulation devices (on-load tap changers (OLTCs) and capacitor banks (CBs)) with photovoltaics (P...

This paper investigates corrosion on high-voltage transmission line structures due to direct current (DC) emitted from the cathodic protection system of nearby pipelines. With the increasing coexistence of power lines and metallic structures, such as pipelines, in a shared corridor, stray current interactions induce electrolytic and electrochemical...

With increasing penetration of renewable energy sources in electric distribution systems, the microgrid is a fundamental building block for grid modernization. Renewable distributed generation (DG) units are connected within a microgrid through interfacing inverters equipped with advanced control schemes, and these inverters play an essential role...

The increasing proximity of transmission lines to urban areas has raised safety concerns due to potential touch and step voltage hazards during transmission line faults. Lacking of a comprehensive safety standard in many regions makes the situation worse. Although both deterministic and probabilistic risk assessment approaches have been attempted f...

This paper introduces a novel threshold-based stator inter-turn fault (SITF) detection and faulty phase identification method for induction motors through the negative sequence stator current analysis, where the negative sequence current magnitude level (NCL) is used for SITF detection, and the negative sequence current’s phase angle (∡12) is used...

Battery energy storage systems are widely used for renewable power generation and electric transportation systems. Bidirectional DC-DC converters (BDCs) are key components in such systems, enabling bidirectional power flow in battery charging and discharging modes. BDCs can be categorized into isolated and non-isolated. Non-isolated BDCs have lower...

This paper proposes an isolated DC-DC converter with a highly flexible voltage gain, which can be adjusted by three independent parameters. The proposed converter also offers the smooth input current, a simple structure and high efficiency. The only switch of the converter experiences extremely low voltage spikes; its output diode works under the z...

In this paper, a novel loss of field (LOF) detection method is proposed for synchronous generators by utilizing a dynamic equivalent circuit model (DECM). The DECM consists of an internal voltage source and an impedance connected in series, and the two parameters are estimated by measuring three-phase currents, three-phase phase-to-ground voltages,...

In this article, a novel high-efficient control based on brain emotional learning for a brushless doubly-fed induction machine (BDFIM) drive is proposed without requiring a detailed machine model. The step change of the control winding (CW) flux for a given torque and speed is the basis of the proposed controller. The control algorithm detects a st...

Stator inter-turn faults (SITFs) constitute a significant portion of induction motor failures. In this paper, a novel two-dimensional (2D) convolutional neural network (CNN)-based SITFs detection technique is proposed for line-connected induction motors, where the fundamental frequency phasor magnitude (FPM) and the 3rd harmonic components of the s...

Transmission structures cost about 50% of the project budget on material for transmission grids. Corrosion of transmission structures is a primary cause of in-service equipment degradation and is an increasing engineering and economic problem, with electric utilities spending more of their maintenance budget on inspection and refurbishment of corro...

The Volt/Var optimization (VVO) enables advanced control strategy development for voltage regulation. With the recent advancement of data-driven approaches and communication infrastructure, real-time decision-making through VVO can effectively address distributed energy resources (DERs) uncertainties without relying on models and topologies of dist...

A Brushless Doubly-Fed Induction Machine (BDFIM) has wide application potential in wind turbines, industrial drives, small hydro power plants, power supply of ships, aircraft starters, and electric vehicles. In electric vehicles, a BDFIM offers a robust structure without needing permanent magnet materials, slip-rings, and brushes, which makes it pa...

The dissolved gas analysis (DGA) data play a crucial role in evaluating the transformer health index (HI). In recent years, data-driven approaches have attracted significant research interest for the HI prediction with various health condition data. However, the DGA data collection is prone to missing or erroneous data due to sensors or data transf...

A multi-microgrid (MMG) consists of several individual microgrids (MGs) within a distribution system to improve the system’s stability and reliability. A MMG can operate in grid-connected or island mode and requires advanced control techniques and effective energy management. This paper proposes a novel energy management approach for a MMG at the t...

In this paper, a robust, multi-modal deep-learning-based fault identification method is proposed for solar photovoltaic (PV) systems, capable of detecting a wide range of faults at PV arrays, inverters, sensors, and grid connections. The proposed method combines residual convolutional neural networks (CNNs) and gated recurrent units (GRUs) to effec...

Combined heat and power microgrids (CHPMGs) have become increasingly popular recently due to their ability to offer cost-effective and resilient solutions to support critical infrastructures. As the centerpiece of a CHPMG, an autonomous real-time multi-energy management system can leverage advanced metering infrastructure to monitor and dispatch va...

The distribution transformer failure may be influenced by its maintenance history and risk index in a distribution network associated with keraunic level, average number of lightning strikes, and protection devices employed. Transformer failure is a rare event, and the number of "failed" labels is much smaller than that of "non-failed" labels in fi...

A resilient power distribution network can reduce length and impact of power outages, maintain continuous services, and improve reliability. One effective way to enhance the system's resilience is to form microgrids during outages. In this paper, a novel dynamic microgrid formation-based service restoration method using deep reinforcement learning...

Microgrids are fundamental building blocks of smart grids. With increasing penetration of renewable energy-based distributed generation (DG) in distribution systems, microgrid formation is an effective way to improve reliability and resiliency by transforming a conventional distribution network into its active form. In this paper, a new microgrid p...

Due to limited reserves and 100% inverter-based resources in an islanded residential microgrid (IRM), largefrequency oscillations may arise during load/generation fluctuations. As an independent grid-forming unit, a battery energy storage system (BESS) can participate in load-frequency control (LFC) to achieve environment-friendly and reliable supp...

DC power flow controllers (DCPFCs) are emerging devices to control power flow in voltage source converter (VSC)-based multi-terminal HVDC (MT-HVDC) grids. In this paper, a novel Newton-Raphson (NR)-based DC power flow solver (DCPFS) is proposed to solve the DC power flow problem (DCPFP) by using a novel multiport interline DC power flow controller...

Railways and electric power systems are two critical infrastructures for the modern society's economic growth. Due to the difficulty of acquiring new lands for their expansion, railways and power lines often share a common corridor to optimize the use of land. However, the AC electromagnetic interference (EMI) between railways and nearby power line...

AC electromagnetic interference (EMI) between railway and nearby power lines causes serious concerns about railway personnel and equipment safety. The AC EMI analysis is usually conducted by complex computer simulation software to estimate induced voltages on rail tracks, and induced voltages can be further used for safety evaluation. However, such...

Due to increasing penetration of renewable distributed generation (DG), conventional distribution networks have been gradually transforming into their active form, where microgrids may serve as fundamental building blocks. As the primary step towards microgrid planning, optimal DGs placement and sizing can reduce the total energy losses by localizi...

The Soft Open Point (SOP) is an emerging power electronic device for active power flow control, reactive power compensation and post-fault service restoration in power distribution networks. In this paper, a novel two-stage multi-scenario optimization method for SOP placement and sizing is proposed to minimize power losses and active power curtailm...

Day-ahead forecasts are required by electricity market investors to make informed decisions on the trading floor. Whereas it is relatively easier to predict the performance of a few large-scale photovoltaic (PV) systems, a large number of small-scale PV systems with a wide geographical spread poses more challenges because they are often not metered...

Recent advancement in design and control of brushless doubly-fed induction machine (BDFIM) has substantially improved its performance. In this article, two high efficient vector control schemes are proposed for the BDFIM drive based on Lyapunov nonlinear techniques. The first scheme aims for speed control with a one-level structure without an inner...

Overloading and load imbalance have a significant impact on the health of distribution transformers. The load of a distribution transformer can be considered in a hierarchical way: individual single-phase customers connected directly to the transformer (the bottom level), the load at each phase (the middle level), and the total load among three pha...

In this paper, a single-inductor multi-input single-output (SI-MISO) DC-DC boost converter is used for solar photovoltaic (PV) systems in DC or AC grids. The converter with N number of inputs combines energy from PV panels along with fuel cells (FCs) to maintain stability. By implementing a new switching algorithm in the converter, the output volta...

With increasing penetration of wind power, accurate prediction of wind speed is essential for planning and operation of power grids. In this paper, a novel two-dimensional (2D) convolutional neural network (CNN)-based wind speed forecasting technique is proposed for an hour-ahead wind speed prediction. The wind speed at a specific time can be predi...

The soft open point (SOP) is an emerging power electronics device in place of normally open points/tie switches in distribution systems. During a fault, service restoration can be effectively achieved by coordinating SOPs and distributed generation units (DGs). In this paper, a novel two-stage SOP-based service restoration method in distribution ne...

Due to independency from physical models and low cost of implementation, machine learning-based condition monitoring methods for solar photovoltaic (PV) systems have recently gained attentions from academia and industry. In this paper, a literature review is conducted on machine learning applications in condition monitoring of PV systems. Different...

High-impact low-probability (HILP) events can significantly threaten the resiliency of electric power grids. In the meantime, the utilization of renewable energy sources (RESs) has introduced serious challenges regarding their variability in the operation and planning of power systems. This paper provides a comprehensive review of power system resi...

One major challenge in the development of solar photovoltaic (PV) systems is their inherent intermittency due to high dependability on meteorological and weather conditions. To address this challenge, providing full statistics information for the look-ahead times can be a potential solution. This paper establishes a two-stage probabilistic framewor...

To maximize reactive power support from a wind power plant (WPP) and maintain power factor at the point of interconnection (POI) within acceptable limits, a novel hierarchical voltage control scheme consisting of a central WPP controller and a local wind turbine generator (WTG) controller is proposed in this article, and both controllers are operat...

To realize operation automation in remote islanded microgrids, a model predictive control (MPC)-based distributed generation (DG) controller is proposed in Part 2 of this article. The developed data-driven predictive model in Part 1 of this article is implemented in Part 2 to realize the proposed MPC controller. The controller does not incorporate...

As one of the dominant forms of renewable energy sources, wind power generation plays an increasingly important role in modern energy landscape. A very short-term wind speed prediction is essential for monitoring and control of power systems with high wind power penetration to improve system stability and reliability. In this article, an accurate f...

In a low-voltage islanded microgrid, the distribution line impedance and relatively large power angle may lead to active and reactive power coupling during voltage and frequency control actions, which cause errors for conventional droop control at interfacing inverters of distributed generation (DG) units. To overcome this issue, in this two-part a...