Gregor Verbic

The University of Sydney · Centre for Future Energy Networks, School of Electrical & Information Engineering

This paper addresses the assumptions underpinning many control schemes for residential demand response (RDR), with particular focus on those that adopt the framework of non - cooperative games. We propose four principal assumptions that we believe are necessary to give a realistic grounding to research on RDR, so that they might be more readily app...

A new algorithm for protection against voltage collapse is proposed. The algorithm makes use of the magnitudes and angles of the local phasors (i.e., bus voltages and load currents). The change in an apparent power-line flow during a time interval is exploited for computing the voltage-collapse criterion. The criterion is based on the fact that the...

A novel methodology for economic evaluation of hydrogen storage for a mixed wind-nuclear power plant is presented in this article in a context of a ldquohydrogen economyrdquo. The simulation of the operation of the combined nuclear-wind-hydrogen system is discussed first, where the selling and buying of electricity and the selling of excess hydroge...

This paper presents an application of a two-point estimate method (2PEM) to account for uncertainties in the optimal power flow (OPF) problem in the context of competitive electricity markets. These uncertainties can be seen as a by-product of the economic pressure that forces market participants to behave in an "unpredictable" manner; hence, proba...

This paper proposes a sequential co-optimization (SCO) framework for the design of greenfield energy hubs, aiming to achieve net zero emissions. The SCO framework offers an evolutionary approach to long-term planning and operation, taking into account various evolving factors such as carbon emission policies, technological and economic advancements...

Greenfield precincts offer an opportunity to develop energy hubs, which can help the transition to carbon neutrality. However, this requires a detailed demand model, which is often not available in the early planning stages. To address this need, this paper proposes a novel methodology for building a demand model using available information, includ...

The significant penetration of rooftop solar photovoltaics (PV) is pushing low-voltage distribution networks to the brink of their technical limits, which increasingly requires distribution system operators (DSO) to limit power exports. The easiest but also the bluntest instrument is to impose a blanket constraint, which is suboptimal and not in th...

The increasing penetration of prosumers, residential customers equipped with distributed energy resources (DER), offers an opportunity to aggregate DER into virtual power plants (VPP) operated as a single dispatchable resource. Yet that raises the question of how to financially reward prosumers for participating in VPPs. Against this backdrop, this...

The increasing penetration of distributed energy resources in low-voltage networks is turning end-users from consumers to prosumers. However, the incomplete smart meter rollout and paucity of smart meter data due to the regulatory separation between retail and network service provision make active distribution network management difficult. Furtherm...

This paper demonstrates the value of power hardware-in-the-loop (PHIL) testing for the study of peer-to-peer (P2P) energy trading. P2P has emerged as a promising candidate for coordinating large numbers of distributed energy resources (DER) that pose a risk to network operations if left unmanaged. The existing literature has so far relied on pure s...

The process of evaluating investments by electricity utilities to subsidize residential battery installations in distribution networks is challenging, because finding efficient investment plans involves reasoning over various sources of uncertainty and consideration of different sizing, location and timing options. This work proposes a novel financ...

This work investigates the extent to which phase change material (PCM) in the building's envelope can be used as an alternative to battery storage systems to increase self-consumption of rooftop solar photovoltaic (PV) generation. In particular, we explore the electricity cost-savings and increase in PV self-consumption that can be achieved by usin...

The uptake of behind-the-meter distributed energy resources (DER) raises the likelihood of voltage problems in low-voltage distribution networks. Network operators increasingly require solar inverters to provide reactive power support using Volt-Var control (VVC) to reduce voltage stress. However, VVC can cause instability in real-time control beca...

This work investigates the extent to which phase change material (PCM) in the building's envelope can be used as an alternative to battery storage systems to increase self-consumption of rooftop solar photovoltaic (PV) generation. In particular, we explore the electricity cost-savings and increase in PV self-consumption that can be achieved by usin...

Abstract This paper proposes a vehicle‐to‐grid (V2G) operation methodology of electric vehicles (EVs) for frequency regulation, EV charging, and state‐of‐charge (SOC) management. This V2G operation methodology exhibits multifunctionality in regard to instantaneous power adjustment of EVs for primary frequency control during charging. The proposed m...

The increasing penetration of behind-the-meter distributed energy resources opens up opportunities to improve distribution grids’ resilience and reliability. In this context, the paper studies islanded operation of radial low-voltage (LV) distribution feeders with a high penetration of prosumers equipped with grid-forming inverters. In contrast to...

Off the southern coast of tasmania, Australia, lies a small island community and tourist hot spot called Bruny Island, known for its beautiful white sandy beaches, rugged coastline, and delicious produce (Figure 1). Just as the island population rises and falls with the holiday peaks, so, too, does the load on the undersea electricity cable connect...

Given the historically static nature of low-voltage networks, distribution network companies do not possess the tools for dealing with an increasingly variable demand due to the high penetration of distributed energy resources (DERs). Within this context, this paper proposes a probabilistic framework for tariff design that minimises the impact of D...

This paper considers energy management in buildings with phase change material (PCM) that serves as a thermal energy storage system. In this setting, the optimal scheduling of an HVAC system is challenging because of the nonlinear characteristics of the PCM, which makes solving the corresponding optimization problem using conventional optimization...

Given the increasing penetration of distributed energy resources (DER) in low-voltage networks, peer-to-peer (P2P) energy trading has been proposed to facilitate DER integration into power systems. In this paper, we investigate P2P energy trading driven by the electrical distance between agents in a low-voltage network. Our market design considers...

This paper presents a novel distributed optimal power flow (DOPF) method for fair distributed energy resource (DER) coordination in the context of mandated rooftop PV inverter control modes. In practice, inverter reactive power control is increasingly required by grid connection codes, which often unfairly curtail PV generation of prosumers towards...

Lack of system inertia is becoming a big concern in modern power systems with a high penetration of inverter-interfaced generation. In this paper, we argue that PV-battery systems owned by end-users can be used as a source of inertia to improve the frequency performance of future grids. To that end, we implement grid-forming control on battery conv...

The coordination of prosumer-owned, behind-the-meter distributed energy resources (DER) can be achieved using a multiperiod, distributed optimal power flow (DOPF), which satisfies network constraints and preserves the privacy of prosumers. To solve the problem in a distributed fashion, it is decomposed and solved using the alternating direction met...

Energy management in buildings using phase change materials (PCM) to improve thermal performance is challenging due to the nonlinear thermal capacity of the PCM. To address this problem, this paper adopts a model-free actor-critic on-policy reinforcement learning method based on deep deterministic policy gradient (DDPG). The proposed approach overc...

This paper reviews approaches for facilitating the integration of small-scale distributed energy resources (DER) into low-and medium-voltage networks, in the context of the emerging transactive energy (TE) concept. We focus on three general categories: (i) uncoordinated approaches that only consider energy management of an individual user; (ii) coo...

This paper is to offer the framework for stochastic eigenvalue analysis with the inertialess (renewable) generation and to verify the influential factor of eigenvalue movement from inertia constant reduction. We analytically investigate the influence of inertia constant and renewable variation on small signal stability with eigenvalue and modal con...

It can be expected that the power systems of the future will be significantly different from today's, especially due to increasing renewable energy sources (RESs), storage systems, and price-responsive users leading to large uncertainty and complexity. The operation of these future grids (FGs) at levels of renewable energy approaching 100% will req...

The rapid rise of PV installations in low-voltage (LV) distribution networks means that they are likely to exceed network hosting capacity. For this reason, distribution network service providers (DNSP) have begun to mandate connection codes, such as inverter Volt/Var control and/or PV active power curtailment, to mitigate the resulting network pro...

The rapid rise of distributed energy resources (DER) has shifted passive electricity consumers to an active prosumer role. However, uncoordinated DER may result in network problems. This demo presents a Raspberry Pi-based hardware prototype that coordinates participating agents in a low-voltage electrical network by solving a distributed optimal po...

The uptake of behind-the-meter distributed energy resources in low-voltage distribution networks has progressed to a point where phenomena including overvoltage and reverse power flow are emerging. The limited nature of supervision and control on these networks require novel tools for operation and planning in this environment. In this paper, we pr...

This paper investigates systemwide short-term voltage stability concerns of power systems due to the multiple parametric uncertainties in the dynamic load model. The impact of regional load model uncertainty can be widespread and may mislead the whole system analysis and subsequent measures, if not properly addressed. This research discloses that t...

This paper focuses on energy management in buildings with phase change material (PCM), which is primarily used to improve thermal performance, but can also serve as an energy storage system. In this setting, optimal scheduling of an HVAC system is challenging because of the nonlinear and non-convex characteristics of the PCM, which makes solving th...

This paper proposes the droop control algorithm for multiple distributed Battery Energy Storage Systems (ESS) with their state of charge (SOC) feedback, shown to be effective in providing grid services while managing the SOC of the ESS. By extending the mathematical links between the ESS SOC and power dynamics for frequency regulation, this paper e...

Battery storage, particularly residential battery storage coupled with rooftop photovoltaics (PV), is emerging as an essential component of the smart grid technology mix. However, including battery storage and other flexible resources like electric vehicles and loads with thermal inertia into a probabilistic analysis based on Monte Carlo (MC) simul...

With the increasing popularity of combining residential photovoltaic systems with battery storages, research, industry, and customers look for ways to determine if such an investment is economically profitable. Simulation programs may serve to predict the profitability and lifetime of the system. In this paper, we use techno‐economic analysis with...

Strategic valuation of efficient and well-timed network investments under uncertain electricity market environment has become increasingly challenging, because there generally exist multiple interacting options in these investments, and failing to systematically consider these options can lead to decisions that undervalue the investment. In our wor...

Strategic valuation of efficient and well-timed network investments under uncertain electricity market environment has become increasingly challenging, because there generally exist multiple interacting options in these investments, and failing to systematically consider these options can lead to decisions that undervalue the investment. In our wor...

This paper proposes a novel cost-reflective and computationally efficient method for allocating distribution network costs to residential customers. First, the method estimates the growth in peak demand with a 50% probability of exceedance (50POE) and the associated network augmentation costs using a probabilistic long-run marginal cost computation...

The home energy management problem has many different facets, including economic viability, data uncertainty and quality of strategy employed. The existing literature in this area focuses on individual aspects of this problem without a detailed, holistic analysis of the results with regards to practicality in implementation. In this paper, we fill...

The thermal inertia of buildings is a flexible resource that can be used for shaping the energy usage pattern of space heating and cooling. However, in some countries, especially Australia, a large number of buildings have low thermal inertia. Given this context, this paper builds on the literature introducing phase change materials (PCM) as a prom...

The paper analyses different trading arrangements in the context of peer-to-peer (P2P) trading. Building on our previous work presented in [1], we use a sensitivity analysis to estimate the impact of each P2P transaction in the network to determine the attribution of costs related to power losses and utilization of the network. We take a closer loo...

The interest in off-grid solar PV system has grown significantly in recent years. The price of suitable batteries started to decline following the price trajectory of solar PV, the curtailment of solar feed-in-tariff in many countries and the increasing electricity price. These are some important factors for grid defection trends. In this paper, we...

The rapid deployment of distributed energy resources (DERs) along with the advances in information and communication technology have led to an increased interest in energy trading at the local level. This paper explores the particular properties of developing local energy trading schemes in low-voltage networks by comparing two different approaches...

The home energy management problem has many different facets, including economic viability, data uncertainty and quality of strategy employed. The existing literature in this area focuses on individual aspects of this problem without a detailed, holistic analysis of the results with regards to practicality in implementation. In this paper, we fill...

In this paper, we propose a new online dynamic security assessment (DSA) framework based on semi-supervised learning and data editing. To reduce the number of labeled samples used by supervised learning in conventional DSA, which is required to ensure a high generalization performance of a classifier, we augment the training set with a large number...

Grid-scale energy storage systems (ESS) have been widely recognized as a technically viable alternative to network augmentation in integrating growing renewable penetration in distribution networks. However, it is challenging to determine efficient and well-timed investment in the grid-scale ESS, considering battery schedules and future uncertainti...

The increasing penetration of distributed generation, such as rooftop PV, is being followed by an uptake of other distributed energy resources such as battery storage and flexible loads, resulting in greater flexibility on the demand side of power systems. Of these resources, space heating and cooling is receiving much attention. At the same time,...

In light of the heightened uptake of distributed energy resources, distributed methods are attracting increased focus. This paper proposes an adaptive scheme to improve the convergence of ADMM on the component-based dual decomposition of the AC OPF. The method incorporates a local curvature approximation scheme, with an underlying parameter update...

In recent decades, there has been a proliferation of behind-the-meter distributed energy resources (DER) and technologies in developed economies, and an increase in renewable energy resources (RER) generally. This rise is attributed to the quest for an increase in carbon-free energy by these countries and other environmental concerns. Furthermore,...

The large deployment of distributed energy resources (DERs) in low voltage networks has introduced new scenarios and opportunities for all users. We present a case study of peer-to-peer (P2P) energy trading under network constraints in a low-voltage network. Decentralised P2P energy trading is one of the future scenarios in the energy sector due to...

Grid-scale energy storage systems (ESS) have been widely recognized as a viable tool for integrating the growing renewable penetration in distribution networks. However, it is challenging to determine efficient and well-timed investment in the grid-scale ESS considering battery operational decisions and future uncertainties, such as varying electri...

To successfully perform the necessary migration towards a sustainable civilization, it is required we exploit both consolidated and emerging technologies. Within this context, the emerging \textit{smart grid} has numerous components, and is closely intertwined with the concept of the \textit{internet of things} (IoT). Both are necessary for the tra...

The increasing uptake of distributed energy resources (DERs) in distribution systems and the rapid advance of technology have established new scenarios in the operation of low-voltage networks. In particular, recent trends in cryptocurrencies and blockchain have led to a proliferation of peer-to-peer (P2P) energy trading schemes, which allow the ex...

In this paper, we present a probabilistic framework to assess the impacts of different network tariffs on the consumption pattern of electricity consumers with distributed energy resources such as thermostatically controlled loads and battery storage; and the resultant effects on the distribution network. A mixed integer linear programming-based ho...

Energy storage systems (EES) are expected to be an indispensable resource for mitigating the effects on networks of high penetrations of distributed generation in the near future. This paper analyzes the benefits of EES in unbalanced low voltage (LV) networks regarding three aspects, namely, power losses, the hosting capacity and network unbalance....

The increasing uptake of residential batteries has led to suggestions that the prevalence of batteries on LV networks will serendipitously mitigate the technical problems induced by PV installations. However, in general, the effects of PV-battery systems on LV networks have not been well studied. Given this background, in this paper, we test the as...

The increasing uptake of distributed energy resources (DERs) in distribution systems and the rapid advance of technology have established new scenarios in the operation of low-voltage networks. In particular, recent trends in cryptocurrencies and blockchain have led to a proliferation of peer-to-peer (P2P) energy trading schemes, which allow the ex...

In light of the increased focus on distributed methods, this paper proposes two accelerated subgradient methods and an adaptive penalty parameter scheme to speed-up the convergence of ADMM on the component-based dual decomposition of the second-order cone programming (SOCP) relaxation of the OPF. This work is the first to apply an adaptive penalty...

Increasing installations of distributed electricity generation have vastly increased the need for stochastic generation and demand data. However, the effects of such installations is uncertain, as high quality data is not always available before an installation is completed. In particular, there is a need for stochastic models of demand and generat...

This paper proposes a hierarchical approach for estimating residential PV and electrical demand models using historical data. In brief, the method involves first clustering historical data into different day types, and then estimating PV and demand models using kernel regression. Clustering is done to capture intra-day variations in the PV and dema...

The electric power system is currently undergoing a period of unprecedented changes. Environmental and sustainability concerns lead to replacement of a significant share of conventional fossil fuel-based power plants with renewable energy resources. This transition involves the major challenge of substituting synchronous machines and their well-kno...

The electric power system is currently undergoing a period of unprecedented changes. Environmental and sustainability concerns lead to replacement of a significant share of conventional fossil fuel-based power plants with renewable energy resources. This transition involves the major challenge of substituting synchronous machines and their well-kno...

In this paper, the impact of load dynamics on the oscillatory stability of power systems is studied. The well-known composite load model is linearized to yield third order transfer functions for active and reactive power dynamics of loads. It is shown that the third order model exhibits a recovery response that is accompanied by damped oscillations...

In this paper, we propose a policy function approximation (PFA) algorithm using machine learning to effectively control PV-storage systems. The algorithm uses an offline policy planning stage and an online policy execution stage. In the planning stage, a suitable machine learning technique is used to generate models that map states (inputs) and dec...

This paper presents a method for harmoniously coordinating roles between generators and faster-acting energy storage systems (ESSs), e.g. batteries, to improve their frequency response and regulation services to the grid, particularly at the high wind penetration. The paper theoretically demonstrates that the proposed droop with the state of charge...

This paper proposes a component-based dual decomposition of the nonconvex AC optimal power flow (OPF) problem, where the modified dual function is solved using the alternating direction method of multipliers (ADMM). This paper is the first to conduct extensive numerical analysis resulting in the identification and tabulation of the algorithmic para...

The increasing penetration of non-synchronous renewable energy sources (NS-RES) and demand side-technologies alter the dynamic characteristics, and particularly, the frequency behavior of a power system. Given this, we propose a framework for assessing renewable integration limits concerning power system frequency performance using a time-series sc...

Demand response (DR) programs incentivize consumers for using their elastic demand for demand shaping, supply-demand balancing and other ancillary and network support services. This paper proposes a dynamic nonlinear pricing scheme for behind-the-meter distributed energy resources (DERs), such as residential batteries, plug-in electric vehicles (PE...