L.G. Meegahapola

• PhD, BSc.Eng.(Hons 1), SMIEEE
• Associate Professor at RMIT University

Power generation from inverter‐based renewable energy sources (RESs), such as solar photovoltaics (PVs), is increasing rapidly in power systems while leading to operational challenges such as frequency regulation. Battery energy storage systems (BESS) have attracted much attention in providing frequency control ancillary services (FCAS), as they pr...

Power systems worldwide face stability challenges as renewable energy integration transforms electricity networks. Renewable energy sources’ fundamentally different operation, intermittency, and physics versus traditional synchronous generators primarily drive these challenges. Ancillary services, traditionally delivered by synchronous generators a...

The strategic deployment of grid-forming inverters (GFMIs) is imperative to fully leverage their potential to stabilise the grid. Otherwise, poorly planned spatial allocation of GFMIs could threaten the overall system stability under network disturbances. There is an urgent need to develop a robust and multidimensional framework for GFMI placement...

Various fault ride-through (FRT) strategies have been implemented in grid-forming inverters (GFMIs), and their ability to support system voltage during faults has been evaluated under various conditions. Each strategy demonstrates different performance characteristics during and after faults. However, less attention has been paid to analysing and i...

This is the Invited Speech I delivered at the IEEE SPEC2024 Conference. The Invited Speech Title “Improving Grid-Forming Inverter Performance under Varying Grid Conditions”. This presentation covered how grid-forming inverters should perform under various grid conditions ( 1) Low and High Inertia, 2) Low and High Short-Circuit Strength, 3) Low and...

Due to the high penetration of renewable energy and the presence of dynamic loads, uncertainties and disturbances in the electricity network have increased significantly. Consequently, the active and reactive power requirements of the network fluctuate rapidly. The conventional control architecture of the grid following voltage source inverter (VSI...

Hybrid AC/DC microgrids are considered as viable solutions to reduce energy conversion losses in microgrids. However, hybrid AC/DC microgrids are susceptible to stability issues during high penetration of dynamic loads (e.g., induction machines). The non-linear dynamics of induction machines, result in sustained voltage/frequency oscillations follo...

Contemporary electricity networks are exposed to operational uncertainties, which may jeopardise the stability of the power grid. More specifically, the increasing penetration level of variable renewable energy generation and uncertainty in load demand are key catalysts for these emerging stability issues. A mathematical relationship is established...

Power synchronisation control (PSC) is commonly used in voltage source inverters due to its grid-forming capability and superior performance under weak grid conditions as compared to other grid-forming inverter (GFMI) strategies. However, there is a notable gap in understanding the application and performance of PSC under various practical operatin...

This paper presents a comprehensive analysis of cost savings and payback periods for the deployment of batteries by commercial and industrial customers, considering several typical tariff structures in the context of Australia. To achieve this, a battery energy management mechanism is proposed that enables battery charging, both from the solar phot...

This study advocates establishing an indicator system for Critical Infrastructures (CIs) resilience assessment to ensure consistency and comparability in future endeavors. Resilience has emerged as a fundamental framework for effectively managing the performance of CIs in response to the challenges posed by disaster events. However, it is evident t...

Inverter‐based distributed generators (IBDGs), mainly solar photovoltaic, connected in medium‐voltage (MV) networks cause challenges, such as voltage limit violations, for distribution network service providers (DNSPs), and require advanced network management strategies to mitigate these challenges. A theoretical analysis of the voltage limit‐induc...

The virtual synchronous generator (VSG) is the most widely used grid-forming inverter (GFMI) control technique. The VSG can provide enhanced ancillary services and improved dynamic response compared to conventional synchronous generators and grid-following inverters (GFLIs). Developing an improved understanding of VSG strategies is vital to deploy...

Effective fault detection allows distribution system operators (DSOs) to provide reliable power to customers in active distribution networks (ADNs). Advantages include faster maintenance, less downtime, fewer critical system events, economic benefits, and prevention of network-wide cascading faults. In this paper, a new fault detection, classificat...

A permanent magnet synchronous generator‐based wind generation system has been predominantly applied in wind farms. With the wide application of wind generation, mechanical shafting attracts wide attention as torsional vibration problems may occur in its mechanical rotational system, which can further affect the power system. The paper first intent...

The past two decades have seen a rapid increase in electric vehicles (EVs) for several reasons, such as policy directives to reduce carbon emissions in the transport sector and technology advancements in the EV industry. However, this has increased the load demand on the power grid, especially in the low‐voltage (LV) network, as most EVs are charge...

Community microgrids are designed by collating local renewable energy resources and energy storage systems to cater for local energy demand. Microgrids can operate in both grid-connected and islanded (off-grid) modes, and they can deliver many benefits to rural and regional communities. For example, they can improve the reliability of local electri...

Due to reduction in power system inertia and frequency regulation reserve with high penetration of power-electronic converter (PEC) interfaced renewable sources, advanced control strategies must be developed to exploit the full potential of solar-photovoltaic (PV) systems to improve the frequency stability. In this paper, a new frequency regulation...

Widespread deployments of optimally placed real-time power quality (PQ) monitoring tools such as distribution level micro-phasor measurement units (D-PMUs or μPMU), digital fault recorders, and PQ analyzers are expected to play a critical role in improving the stability and reliability of the smart grid. In this paper, an improved PQ disturbance (P...

This document is a summary of a report prepared by the IEEE PES Task Force (TF) on Microgrid (MG) Dynamic Modeling, IEEE Power and Energy Society, Tech. Rep. PES-TR106, 2023. In this paper, the major issues and challenges in microgrid modeling for stability analysis are discussed, and a review of state-of-the-art modeling approaches and trends is p...

Over the past years, buildings and CIs have been largely affected by climate change-related extreme events. Being a tropical nation, Sri Lanka is adversely impacted by the current climate change landscape. Many nations have taken actions, generally known as Climate Change Adaptation (CCA) strategies, to mitigate the negative impacts on the infrastr...

With the advancements of the battery energy storage systems (BESSs), reduction of their manufacturing costs and government subsidies, the BESS uptake is likely to increase rapidly in power distribution networks. This paper investigates the effects of residential BESSs on low-voltage (LV) networks using the actual household load profiles equipped wi...

High voltage direct current (HVDC) networks are transforming ac power grids to hybrid ac/dc power grids; hence hybrid ac/dc power grids are facing new stability challenges. In this paper, a decentralised control scheme based on model predictive control (MPC) is proposed to enhance the stability of hybrid ac/dc power grids under disturbances. The pr...

With the growing pressure to substitute fossil fuel-based generation, Renewable Energy Sources (RES) have become one of the main solutions from the power sector in the fight against climate change. Offshore wind farms, for example, are an interesting alternative to increase renewable power production, but they represent a challenge when being inter...

The design and operation of performant and safe electric vehicles depend on precise knowledge of the behavior of their electrochemical energy storage systems. The performance of the battery management systems often relies on the discrete-time battery models, which can correctly emulate the battery characteristics. Among the available methods, elect...

Real-time monitoring tools and their optimal measurement infrastructure are expected to play a critical role in smart grid applications. These applications require greater measurement precision and speed, which is not possible with conventional measurement devices. Due to their high economic burden and superseded technology, transmission level phas...

Voltage stability is considered as one of the key concerns of hybrid AC/DC power grids, the mechanism of which can be quite complicated and involves multiple factors. This chapter provides a comprehensive overview on the concepts, and main causes and analysis methods of two voltage stability issues including the large-disturbance and small-disturba...

The utilisation of HVDC transmission has brought complex dynamics to the conventional AC power grids dominated by the synchronous generator. Rotor angle stability, as one of the major dynamic concerns, has been considerably affected by the frequent interactions with different HVDC systems. This chapter provides a comprehensive overview on the conce...

The move towards a greener energy mix to fight climate change propels investments in converter-interfaced resources such as wind and photovoltaics, energy storage systems and electric vehicles. The ongoing evolution of the power system is occurring at a very fast pace, challenging transmission and distribution system operators to seek solutions tha...

Wind speed characteristics may have a significant impact on the power system operation, stability and dynamics. Hence, appropriate modelling and quantification of wind probability distribution function (PDF) are critical for probabilistic power system analysis. Weibull distribution is the most widely used PDF for power system (particularly power sy...

Demand response programs can bring many benefits to electricity consumers, distribution network service providers, and system operators. However, the complexity and characteristics associated with the loads connected to customer premises and the baseline calculation process still require considerable research to exploit maximum benefits from demand...

A repetitive predictive control for grid-connected inverter current control scheme is presented in this paper under voltage harmonic distortion in the stationary reference frame. Predictive control is an approach that uses a receding horizon to achieve the optimal track for the reference. In this approach, the repetitive controller behavior is adde...

Massive integration of converter-interfaced distributed energy resources (CDERs) has resulted in many emerging stability issues and significantly complicated the dynamics of active distribution networks (ADNs). Large quantities of CDER systems with complex structures, time-varying parameters and ‘black-box’ controllers not only make the system mode...

This chapter delineates the fundamental and advanced concepts associated with frequency stability and control of hybrid AC/DC power grids. As power grids are transforming to hybrid AC/DC power grids with HVDC transmission systems and high penetration of power electronic converter (PEC) interfaced renewable power generation sources, the electrical d...

In contrast to the conventional synchronous generators, power electronic converter interfaced renewable power generation, such as wind and solar-PV plants is typically sited in remote geographic locations in the power grid. Therefore, inevitably, the generated power from these sources has to be transmitted through long-distance transmission corrido...

Modelling and control of hybrid AC/DC power grids are of paramount importance for power grid stability and dynamics studies. Therefore, accurate representation of the AC and DC grid equipment is vital to capture the stability boundaries of the hybrid AC/DC power grid. This chapter provides a comprehensive overview on the modelling and control techn...

This chapter introduces different HVDC technologies used in HVDC systems with fundamental theories associated with each HVDC technology. The line commutated converter HVDC technology is introduced with details of different line commutated converter HVDC topologies and the fundamental operation principles of line commutated converter HVDC technology...

This book covers modeling, control and stability aspects of hybrid AC/DC power networks. More specifically, this book provides an in-depth analysis of the stability and control aspects of hybrid AC/DC power grids, with comprehensive coverage of theoretical aspects of conventional stability issues (e.g., small-signal stability, voltage stability and...

This chapter introduces coordinated control schemes used in hybrid AC/DC power networks. A variety of control schemes including control schemes which can control multiple system parameters, realise balanced power sharing, minimise transmission power losses, and damp oscillations are discussed in this chapter. Moreover, the model predictive control...

Electric vehicles (EVs) are penetrating rapidly into the transport sector while making profound implications on the electricity and energy sectors. Although EVs have many benefits, it poses several challenges on power grid operators. Uncoordinated EV charging is one of the critical issues that need to be addressed to mitigate the potential adverse...

In this paper, an adaptive virtual impedance-based universal voltage source converter (VSC) control scheme has been proposed to improve the stability, and power-sharing performance of VSC interfaced distributed energy resources in hybrid AC/DC microgrids with different feeder characteristics. The proposed control scheme modulates the VSC output imp...

Advanced metering infrastructure has been widely recognized as a key enabling factor for delivering a range of benefits to the electricity industry as well as to energy consumers. The data is commonly used for billing and to educate consumers so they can make economically optimal decisions on choosing between electricity retail plans. More importan...

This paper proposes a novel hybrid AC/DC microgrid architecture incorporating a central energy storage system (ESS) for both the AC and the DC sub-grids. To ensure effective operation of the proposed hybrid AC/DC microgrid architecture, a coordinated control strategy between the central ESS and the inter-linking converter (ILC) is proposed in the p...

Power network operators are rapidly incorporating wind power generation into their power grids to meet the widely accepted carbon neutrality targets and facilitate the transition from conventional fossil-fuel energy sources to clean and low-carbon renewable energy sources. Complex stability issues, such as frequency, voltage, and oscillatory instab...

Power network operators are rapidly incorporating wind power generation into their power grids to meet the widely accepted carbon neutrality targets and facilitate the transition from conventional fossil-fuel energy sources to the clean and low-carbon renewable energy sources [...]

This paper presents a comparative analysis of six sampling techniques to identify an efficient and accurate sampling technique to be applied to probabilistic voltage stability assessment in large-scale power systems. In this study, six different sampling techniques are investigated and compared to each other in terms of their accuracy and efficienc...

Increasing power system stability challenges are being witnessed worldwide, while transitioning toward low‐carbon grids with a high‐share of power electronic converter (PEC)‐interfaced renewable energy sources (RESs) and distributed energy resources (DERs). Concurrently, new technologies and operational strategies are being implemented or proposed...

Inverter-based generation sources' significant uptake has seen most power system operators place a strong focus on unlocking their capability to respond to frequency excursions. Consequently, the effective utilization of conventional generation assets to improve frequency regulation in power systems has received less focus. This letter highlights t...

The first swing rotor angle stability is still an important stability challenge for modern power systems integrated with a large number of renewable energy-based sources, such as wind farms and solar-photovoltaic farms. Therefore, innovative strategies must be developed to exploit the full potential of doubly fed induction generators (DFIGs) to imp...