Power System Infrastructure Research Articles

Secure DLMS/COSEM communication for Next Generation Advanced Metering Infrastructure

Power System infrastructure is one of the critical components of any nation. The automation of the power system is essential for the reliable and secure operation of the grid. Data plays a vital role in any automated system. So, data security should be inherently present in any automated system for the proper operation of the available components. For the automation of metering system, Advanced Metering Infrastructure (AMI) is being deployed in the power system. A smart meter is a critical component of AMI, whose data is used for load forecasting, scheduling, billing, and energy management. DLMS-COSEM acts as an application layer protocol for meter data exchange. This paper provides a detailed understanding of the DLMS-COSEM communication vulnerabilities, communication attack scenarios, high-security features, authentication procedures and suggests the best methodologies to be followed by a client or third-party system while communicating to the DLMS-COSEM servers in order to have a secure data exchange.

Impact Evaluation of Malicious Control Commands in Cyber-Physical Smart Grids

The Smart Grid is vulnerable to cyber-attacks due to its integration with a variety of information, communication, and control technologies. If undetected by deployed security systems, cyber-attacks could damage critical power system infrastructure and disrupt services to a very large number of energy customers. In particular, cyber attackers could hijack the smart grid by injecting malicious commands. To provide insight into these concerns, we propose an approach that develops a new tool for the real-time Cyber-Physical Security Assessment (CPSA) of malicious control commands that target physical smart grid components. The tool is able to detect and protect the system against known Trojans (such as BlackEnergy). It also efficiently and effectively monitors the health of the power system in real-time and detects the presence of malicious commands. The security analysis of our approach includes a look at three system-generated metrics: system susceptibility, access points, and threat capability. The performance analysis includes a look at the system overhead, scalability, accuracy, robustness, and execution and response times. Our proposed approach was tested on a 42-bus power system with 24 substations. The developed tool could be extended and used by power system operators to assess and mitigate the impact of cyber-attacks on the smart grid.

Machine learning based false data injection in smart grid

Smart Grid is the seamless integration of advance digital communication network, state of the art control technologies, and power system infrastructure working together as an entity to ensure the reliability, sustainability, and stability of the power infrastructure. Digital communication network with is the key to the reliability of Smart Grid as all control actions are deemed upon the data transmitted by a communication network. With false data, however, the same digital communication network can lead to anomalies like abnormal disruptions, load shedding, malicious attacks and power theft. Robust False data injection attack methods proposed till now demand for the complete knowledge of interconnected power grid network topology. In this paper, three network topology independent techniques for false data injection into the smart grid are proposed based on linear regression, linear regression with time stamp, and by using delta thresholds. To make injected false data more unlikely to be detected, it is constructed to fill up the missing measurements in real-time data. The robustness of proposed attack algorithms are stated by state-of-the-art defence techniques, i.e. Bad Data Detection, AC State estimation, Support Vector Machine, and Temporal Behaviours based False data detection.

Enhanced cyber‐physical security using attack‐resistant cyber nodes and event‐triggered moving target defence

A cyber-physical authentication strategy to protect power system infrastructure against false data injection (FDI) attacks is outlined. The authors demonstrate that it is feasible to use small, low-cost, yet highly attack-resistant security chips as measurement nodes, enhanced with an event-triggered moving target defence (MTD), to offer effective cyber-physical security. At the cyber layer, the proposed solution is based on the MULTOS Trust-Anchor chip, using an authenticated encryption protocol, offering cryptographically protected and chained reports at up to 12/s. The availability of the Trust-Anchors allows the grid controller to delegate aspects of passive anomaly detection, supporting local as well as central alarms. In this context, a distributed event-triggered MTD protocol is implemented at the physical layer to complement cyber side enhancement. This protocol applies a distributed anomaly detection scheme based on Holt-Winters seasonal forecasting in combination with MTD implemented via inductance perturbation. The scheme is shown to be effective at preventing or detecting a wide range of attacks against power system measurement system.

A Vision to Enhance Transmission Security: The Case of Switzerland's Power System

It is hard to imagine life without electricity. Electrical energy is constantly consumed to allow humanity to carry out diverse activities ranging from charging mobile phones to controlling the flow of vehicles and pedestrians with traffic lights. Due to its widespread usage and significance, some people take the availability of electric power for granted and expect that the lights will always turn on when they turn on the switch. Nevertheless, when illuminating our rooms, we need to appreciate that an extensive power system infrastructure is in place to securely generate, transport, and distribute electrical energy to our homes.

Impacts of electric vehicle deployment on the electricity sector in a highly urbanised environment

The developments in electric vehicles (EVs) are driven by the need for cleaner and more efficient road transport, but vehicle charging poses significant challenges to the electric grid and electricity sector planning. These challenges are further amplified in the case of a highly urbanised and densely populated small island state, like Singapore, with limited space and options for electricity sector planning. In response, this study aims to evaluate the impacts of a large-scale EV deployment on the electricity sector from a whole-system perspective with focus on investments in the power sector for EV adoption, assuming minimum deployment of advanced “smart-grid” and “vehicle-to-grid” technologies. Findings suggest that a small-scale deployment of EVs below 20% replacement can be economically manageable. A large-scale of deployment of EVs would inevitably bring a notable impact to the electricity sector regardless the state of advanced technology development. From the perspective of integrated planning, cities, especially those with high vehicle density, should continue to exercise caution with EV deployment. A large-scale deployment should be pursued after a “stress-test” of the power system infrastructure from both the technical and economic perspectives.

Travel Activity Based Stochastic Modelling of Load and Charging State of Electric Vehicles

The uptake of electric vehicles (EV) is increasing every year and will eventually replace the traditional transport system in the near future. This imminent increase is urging stakeholders to plan up-gradation in the electric power system infrastructure. However, for efficient planning to support an additional load, an accurate assessment of the electric vehicle load and power quality indices is required. Although several EV models to estimate the charging profile and additional electrical load are available, but they are not capable of providing a high-resolution evaluation of charging current, especially at a higher frequency. This paper presents a probabilistic approach capable of estimating the time-dependent charging and harmonic currents for the future EV load. The model is based on the detailed travel activities of the existing car owners reported in the travel survey. The probability distribution functions of departure time, distance, arrival time, and time span are calculated. The charging profiles are based on the measurements of several EVs.

Grid Forming Converters in Renewable Energy Sources Dominated Power Grid: Control Strategy, Stability, Application, and Challenges

The renewable energy sources (RESs) dominated power grid is an envisaged infrastructure of the future power system, where the commonly used grid following (GFL) control for grid-tied converters suffers from lacking grid support capability, low stability, etc. Recently, emerging grid forming (GFM) control methods have been proposed to improve the dynamic performance and stability of grid-tied converters. This paper reviews existing GFM control methods for the grid-tied converters and compares them in terms of control structure, grid support capability, fault current limiting, and stability. Considering the impact of fault current limiting strategies, a comprehensive transient stability analysis is provided. In addition, this paper explores the typical applications of GFM converters, such as AC microgrid and offshore wind farm high-voltage direct current (OWF-HVDC) integration systems. Finally, the challenges to the GFM converters in future applications are discussed.

Blockchain-Based Energy Applications: The DSO Perspective

This paper discusses blockchain-based energy applications from the distribution system operator (DSO) perspective. Blockchain has a potential impact on newly emergent actors, such as electric vehicles (EVs) and the charging facility units (CFUs) of the electricity grid. Although Blockchain offers magnificent decentralized solutions, the central management of DSOs still plays a significant, non-negligible role, owing to the reality of the existing grid structure. Numerous related studies of proposed blockchain-based EV systems have investigated the energy costs of EVs, fast and efficient charging, privacy and security, P2P energy trading, sharing economy, the selection of appropriate CFUs location, and scheduling. However, cooperation with DSO organizations has not been adequately addressed. Blockchain-based solutions mainly suggest an entirely distributed and decentralized approach for energy trading; however, converting the entire power system infrastructure is considerably expensive. Building a thoroughly decentralized electricity network in a short time is nearly impossible, particularly at the national grid level. In this regard, the applicability of the solutions is as significant as their appropriateness, especially from the DSO perspective, and must be examined closely. We searched and analyzed the blockchain literature related to EVs, CFUs, DERs, microgrids, marketing, and DSOs to define the DSO-based requirements for potential blockchain applications in the energy sector, specifically EV evolution.

Recent Research and Development of Microgrids in Parana

HIGHLIGHTS Efforts in research to enable a microgrid-based power system infrastructure are shown. In a first level, by the optimization of the assets within a microgrid via multi-objective optimization; In a second level, by the optimization of microgrid while connected to the main grid via OPF analysis; In a third level, by the optimization of multi-microgrids connected together and to the grid. Alternatively, by considering decentralized energy markets as an integration approach.

Analysis and Evaluation of Cyber-attack Impact on Critical Power System Infrastructure

ABSTRACT This paper identifies and proposes two novel indices for cyber-attack impact evaluation. It focuses to create a simple common platform to compare cyber intrusion impact among different critical infrastructure using time as a base parameter. The first index is ‘Service Unavailability Cyber Impact Factor (SUCIF)’ having score range from 0 to 1, where 0 indicate cyber disaster and 1 indicates no breach. To estimate the score, detail information regarding system unavailability or malfunctioning is required. It can be used to analyze those systems whose detail cyber-physical infrastructure is not available. The second indicator named ‘Time Based Cyber Impact Factor (TBCIF)’ uses graph-based bad node detection technique to determine the score point similar to SUCIF. For this, optimal time and expected time for incursion detection plays a vital role to generate impact score. This index is suitable for test systems whose physical or cyber layer architecture is known. This research uses SUCIF index to compare hacking impact on Ukrainian Power Grid (UPG) and Saudi Aramco Oil and Gas Company (AOGC). To legitimize TBCIF score, it has been used to compare the intrusion impact of different IEEE test systems. This index is more consistent for the smart grid network.

Probabilistic impact of wind energy integration on distribution transformers

In traditional power grid, the direction of power flow of transformers is usually fixed in one direction. However, with the integration of the renewable energy sources, such as wind farms, the power flow in the grid becomes fluctuating and uncertain, which may cause the reverse power flow passing the transformer. For example, excessive reverse power flow may lead to the increase of transformer power loss and challenge the thermal stability of the transformer. This paper investigates the impact of wind energy integration on the existing power system infrastructure, such as distribution transformers. Probabilistic power flow (PPF) method is used for the analysis. Firstly, a sampling method based on Halton sequence is applied for PPF calculation. Then, to ensure the accuracy of probabilistic power flow calculation, the correlation between wind speeds of different wind farms is considered. A 30-Bus system is used for the probabilistic analysis of the transformer reverse power flow with different level of wind penetration. The results show that the reverse power flow of transformer may occur before 100% wind penetration is achieved. The higher the total wind power capacity in the grid causes the greater probability of transformer reverse power flow. Also, the location of wind farms will also affect the probability of transformer reverse power flow.

A Systematic Method for Power System Hardening to Increase Resilience Against Earthquakes

Although natural disasters have recently imposed enormous damages to power system infrastructures, resilience enhancement through hardening measures is not usually compensated in conventional power system planning. In this article, a framework is proposed to enhance the resilience of distribution systems against earthquakes. In particular, it focuses on substations’ retrofit whose failure can affect the distribution system, imposing outages to the customers connected to it. A knapsack based heuristic method, which considers the bus configuration of substation is proposed to select the substation components for hardening. The potential failure of substation components that would lead to complete unavailability of substation is evaluated through minimal cut set-fault tree analysis. A criterion for resilience enhancement is proposed, including hardening cost, cost incurred by damaged components, cost of customers’ interruption in the distribution system level, and power generation cost of Distributed Energy Resources. A penalty mechanism taking into account the component repair time is used to estimate interruption costs. The impact of earthquakes on substation components is modeled using fragility curves. A case study with real earthquake characteristics is considered and Monte Carlo simulation is used to capture the stochastic failure of substation components. The results show that power transformers and circuit breakers at 20 kV are the most critical components in the retrofitting strategies.

Multi-Year High-Voltage Power System Planning Considering Active Power Curtailment

Integrating active power curtailment (APC) of renewable energy sources (RES) in power system planning reduces necessary investments in the power system infrastructure. In current target grid planning methods, APC is considered by fixed curtailment factors without considering the provided flexibility to its full extent. Time-series-based planning methods allow the integration of the time dependency of RES and loads in power system planning, leading to substantial cost savings compared to the worst-case method. In this paper, we present a multi-year planning strategy for high-voltage power system planning, considering APC as an alternative investment option to conventional planning measures. A decomposed approach is chosen to consider APC and conventional measures in a long-term planning horizon of several years. The optimal investment path is obtained with the discounted cash flow method. A case study is conducted for the SimBench high-voltage urban benchmark system. Results show that the time-series-based method allows for reducing investments by up to 84% in comparison to the worst-case method. Furthermore, a sensitivity analysis shows the variation in total expenditures with changing cost assumptions.

Review on GPS spoofing‐based time synchronisation attack on power system

Power utilities implement cyber-security defence with a philosophy of defence in-depth. Firewall and air-gapped systems are widely used to harden cybersecurity defence of critical power system infrastructure. However, cyber-attack, such as global positioning system (GPS) spoofing, that can compromise the air-gap system has not been investigated thoroughly. As a geographically dispersed cyber-physical system, the power system relies heavily on the GPS to keep time synchronisation of different parts with high precision. GPS spoofing-based time synchronisation attack (TSA) could induce disorder in time synchronisation, and negatively impact or even disable monitoring and control function of the power system via their operation mechanism. The principles of GPS-based time synchronisation and GPS spoofing-based TSA are introduced. Time synchronisation and operation mechanism of typical monitoring and control systems of the power systems are analysed. Thereafter, the consequences of TSA against these systems are analysed. Various techniques that can be used to defend against TSA are depicted and their performances are analysed.

Shore Charging for Plug-In Battery-Powered Ships: Power System Architecture, infrastructure, and Control

This article reviews the available systems for shore-to-ship high-power charging, including recent technologies, control methods, and related challenges. The battery charging path from shore to the onboard battery involves several main components and control functions, such as power electronics converters, transformers and passive elements, plugs and interconnectors, as well as charging energy management system (EMS). A comparison of different charging systems, such as ac, dc, and wireless solutions, and the applicability of each system are discussed. Furthermore, the recent commercial shore-to-ship interfaces for charging purposes are introduced. Finally, a generic overview of the control functions needed for shore charging is provided.

The Simultaneous Impact of EV Charging and PV Inverter Reactive Power on the Hosting Distribution System’s Performance: A Case Study in Kuwait

Recently, electric vehicles (EVs) have become an increasingly important topic in the field of sustainable transportation research, alongside distributed generation, reactive power compensation, charging optimization, and control. The process of loading on existing power system infrastructures with increasing demand requires appropriate impact indices to be analyzed. This paper studies the impact of integrating electric vehicle charging stations (EVCSs) into a residential distribution network. An actual case study is modeled to acquire nodal voltages and feeder currents. The model obtains the optimal integration of solar photovoltaic (PV) panels with charging stations while considering reactive power compensation. The impact of EV integration for the case study results in two peaks, which show a 6.4% and 17% increase. Varying the inverter to the PV ratio from 1.1 to 2 decreases system losses by 34% to 41%. The type of charging is dependent on the maximum penetration of EVCSs that the network can install without system upgrades. Increasing the number of EVCSs can cause an increase in power system losses, which is dependent on the network architecture. Installing PV reduces the load peak by 21%, and the installation of PV with consideration of reactive power control increases system efficiency and power delivery.

What does the GB power outage on 9 August 2019 tell us about the current state of decarbonised power systems?

The GB power blackout, that happened on 9 August 2019, was a unique stress test exposing fault lines brought about by the rapid changes due to the decarbonisation drive and penetration of smart grids technologies. It has demonstrated that, as a significant amount of new equipment and controls were added to the system in a very short time, the probability of common, hidden modes of failures has significantly increased. In the face of declining reliability, maintaining the status quo is not an option. While currently increasing the (N-1) security margin could prove to be expensive, the balance of costs and benefits is likely to change in future. Especially wider application of innovative frequency controls, including “virtual inertia” and Remedial Action Schemes, could help reduce the costs. Distributed Generation (DG) reached such a high penetration level that it cannot be treated any longer as negative demand. Traditional under-frequency load shedding should be made more selective. Interactions between the power system and other infrastructures are still poorly understood and there is a significant risk that if the current compartmentalised approach to their governance and operation is not changed, we may see more unexpected consequences of disturbances across the whole system.

A Review on Smart Grid Internet of Things

Smart electrical network or better known as Smart Grid is one form of transformation and technological reform in the electricity industry. Smart Grid is a modern electrical energy network that intelligently integrates power grids with communications devices that support electricity generation and distribution networks to be more attractive, communicative and qualified. Smart Grid is also able to prevent and to isolate the interference quickly and present information on electrical data in real time. While the Internet of Thing (IoT) is a method that aims to maximize the benefits of internet connectivity to transfer and to process data or information through an internet network wirelessly, virtual and autonomous. IoT technically can be encouraged in developing smart grid network by integrating main power system infrastructure from generating side to end consumer through wireless sensor network automatically. With the utilization of IoT is expected to improve the reliability of information systems from the power grid as well as improve the efficiency of existing electrical infrastructure. This paper will present the concept of smart grid technology, IoT and discuss the IoT design and application model in smart grid network.

Considering distribution grids and local flexibilities in the prospective development of the European power system by 2050

Previous works proposed a tool coupling models of a prospective outlook on long-term energy systems and a transmission grid investment and dispatch, focusing on the representation of the European transmission grid and its development on the horizon 2050–2100. In this paper, this prospective tool is further improved with the capacity to compute voltage as well as active and reactive power flows at the level of the distribution grid. This added capacity allows analyzing various issues related to the integration of variable energy resources in three representative real medium voltage distribution grids (urban, rural and semi-urban). Technical flexibility solutions such as on-load tap changers, variable energy resources curtailment and storage technologies are modeled and compared to reinforcement. A cost comparison between these flexibility solutions is also carried out. Finally, the new version of the tool is used to evaluate the CO2−eq emissions linked to the development of the European power system infrastructure, with flexibility solutions, up to the year 2050 (both high voltage alternative and direct current lines reinforcement being considered) under a 2 °C climate energy policy scenario. Results show that it exists various options for the development of the European grid infrastructure, which are clearly sensitive to the level of accuracy in the representation of the physical infrastructures and their technical limitations. Being able to represent the distribution grid, in addition to the transmission one, has a noticeable impact on the prospective outlook of the European power systems both in terms of infrastructure reinforcement and estimation of the needs of flexibility solutions.