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To allow the large-scale integration of renewable energy sources into the grid, VSC-HVDC is commonly utilized. However, with greater integration, several power system stability issues arise. In this study, we examined the small-signal rotor angle stability of a model of the Australian power system with embedded VSC-based HVDC links. A simplified model of the Australian power network was used to connect the potential geothermal resources in the region of Innamincka using a 1100 km HVDC link. We observed that the introduction of the new source of geothermal power generation had an adverse impact on the damping performance of the system. Therefore, two forms of stabilization are examined here: (i) generator power system stabilizers (PSS) fitted to the synchronous machines, which are used to convert geothermal energy to electrical power; and (ii) power oscillation damping controllers (PODs) fitted to the VSC-HVDC link. In the case of the PODs, two types of stabilizing input signals are considered: (i) local signals such as power flow in adjacent AC lines, and (ii) wide-area signals such as bus voltage angles at key nodes in the various regions of the system. It was concluded that the small-signal rotor angle stability of the interconnected AC/DC system can be greatly enhanced by employing the designed damping controllers. [ABSTRACT FROM AUTHOR]

Due to intermittent characteristics and lack of inertia and damping properties, high penetration of renewable energy sources in power grids could bring about a series of security issues related to power system stability and control. In many countries and regions, therefore, power regulators tend to request self-frequency control ancillary services (FCAS) of renewable power generation, which could introduce further obstacles to utilize clean and inexhaustible wind power, solar energy, and the like in large scale. This paper aims to address such a challenge by presenting a tiered energy storage system (TESS) for self-provision of frequency regulation services. The TESS is composed of different types of energy storage devices aimed at rapid response speed, sufficient storage capacity, and acceptable investment/operation costs. The proposed method can be applied for the FCAS of power grids with high-penetration renewable energy integration. Based on the real wind power generation and electricity demand, simulations were carried out to demonstrate the feasibility of the self-FCAS by the developed TESS. [ABSTRACT FROM AUTHOR]

Remote areas and islands isolated from the main electric power system ensure reliability and stability of power supply using diesel generation. Due to the high purchase and transportation costs of diesel fuel, isolated communities are exploring other options for efficient and reliable power supply. Renewable energy sources can reduce operating costs, although are unable to achieve high penetration without expensive and complex enabling technologies such as energy storage. Furthermore, the stochastic and intermittent nature of renewable sources (i.e., wind and solar) makes the control system complex, decreasing power system reliability and requiring highly qualified personnel in local control centres. The problem becomes particularly acute when diesel engines are forced to operate at partial load, resulting in poor combustion efficiency and potential engine damage. This paper suggests a fuel-efficient control strategy, adopting low load diesel application to reduce fuel consumption and improve renewable energy penetration without overcomplicating the control architecture. A mathematical model is initially developed, then validated against real data, to facilitate comparative assessment of various control approaches. Optimised control methodologies are shown to deliver fuel savings of 16.7%, with a 14% increase in renewable energy penetration, in comparison to conventional management. [ABSTRACT FROM AUTHOR]

Abstract Remote communities increasingly integrate renewable source generation to reduce the environmental and economic impact of diesel generation. Despite benefits scaling proportionally with the level of renewable penetration, most systems restrict renewable utilisation to below 30% of annual production. Identifying system complexity as a key barrier to renewable uptake, this paper investigates methodologies to simplify integration of high renewable penetrations. Three approaches are considered, via three Australian case studies; King Island, Tasmania (approach one), Flinders Island, Tasmania (approach two), and Rottnest Island, Western Australia (approach three). Approach one details a methodology for wind plus storage integration. Approach two details a methodology for wind, solar PV, plus storage integration. Approach three details a methodology for wind and solar PV integration, without storage. All approaches facilitate high renewable penetrations, with each island majority renewable supplied. Approach one benchmarks system performance, with King Island one of the worlds' earliest high penetration renewable islands. Approach two explores benefit via renewable diversification. Approach three investigates rationalisation of energy storage via low load diesel and demand management technology substitution. For approach three a 32% reduction in capital cost was observed, identifying commercial justification for the approach via deferral of energy storage integration. Highlights • High penetration renewable energy power systems using diesel engine were studied. • Annualised system behaviour was investigated for multiple isolated power systems. • The role of enabling technologies/methodologies was compared across case studies. • Battery storage rationalisation can effectively reduce system capital cost. • Advanced diesel technologies substitute for battery storage without major penalty. [ABSTRACT FROM AUTHOR]

Harmonics and waveform distortion is a significant power quality problem in modern power systems with high penetration of Renewable Energy Sources (RES). This problem has attracted more attention in recent decades, owing to the increasing integration of power electronic devices and nonlinear loads into power systems. In this paper, Artificial Intelligence (AI) techniques used in different aspects of analyzing harmonics in electrical power networks are reviewed. The tasks of spectrum analysis and waveform estimation or prediction, harmonic source classification, harmonic source location and estimation, determination of harmonic source contributions, harmonic data clustering, filter-based harmonic elimination, and Distributed Generation (DG) hosting capacity in the context of harmonics are considered. The applications of AI in these tasks have been addressed within the literature and are reviewed in this paper. Different AI techniques applied in the study of harmonics such as artificial neural networks, fuzzy systems, support vector machine and decision tree are reviewed. AI techniques mostly outperformed traditional methods in harmonic analysis, particularly under varying operating condition. However, there is still room for improvement regarding the use of combinations of techniques, ensemble learning, optimal structures, training algorithms and further comprehension. This review provides researchers with an insight into research trends in harmonic analysis and outlines opportunities for further research on this increasingly important topic. • Review of AI applications in different tasks regarding harmonic analysis. • Comprehensive search and detailed evaluation of the methods both in text and in tabular form. • Evaluation of pros and cons of different AI methods by adopting a critical review approach. • Statistics of the research trend in AI techniques applied to harmonic analysis. • Recommendations for AI application in harmonic analysis.and future research directions. [ABSTRACT FROM AUTHOR]

Traditional engine load limits restrict a diesel engine's range and its ability to load share. Accordingly, to achieve high renewable penetrations, diesel generation is conventionally turned off, positioning diesel in competition with variable renewable generation. While this approach maximises renewable penetration (environmental gain), it is uneconomic, requiring costly and complex enabling technologies such as battery storage. For many isolated communities the commercial, technical and social barriers associated with storage integration prove insurmountable. A stalemate results, with owners unable to transition to renewable generation due to inflexible diesel technologies. In this respect, it is easy to view diesel generation as an obstacle to renewable integration. Thankfully, modified diesel technologies can offer improved flexibility without the cost or complexity of energy storage. This paper details the development and testing of both low load and variable speed technologies, each able to improve the performance of diesel generation. Two isolated power system case studies are modelled, with Cape Barren island increasing renewable penetrations to between 41.3% to 58.0% compare to conventional penetrations of 7.7% to 10.1%. For Lady Elliot island the modelled range is 26.7% to 28.5% in comparison to a base of 5.3%. The results serve to recommend modified diesel application as a precursor to battery storage integration. • Low load and variable speed diesel technologies are experimentally investigated. • Variable speed hybrid approach is developed to mitigate converter losses. • Benefit is identified for modified application in battery-less systems. • The approach permits high renewable energy penetrations without storage. [ABSTRACT FROM AUTHOR]

To reduce the reliance on fossil fuel-based generation, many countries expand the use of renewable energy sources (RES) for electricity production. The stochastic and intermittent nature of such sources (i.e., wind and solar) poses challenges to the stable and reliable operation of the electric power system (EPS) and requires sufficient operational flexibility. With continuous and random changes in the EPS operational conditions, evaluating the system flexibility in a standardized manner may improve the robustness of planning and operating procedures. Therefore, the development of fast algorithms for determining system flexibility is a critical issue. In this paper, the flexibility of the EPS with high wind energy penetration is calculated in real time. In this context, the EPS flexibility is understood as the ability of the system to maintain a balance under irregular and short-term active power variations during a specified time by using the flexibility resources. The EPS flexibility calculation relies on a deterministic method developed to qualitatively and quantitatively assess the EPS readiness to changes in load. Accurate wind power forecasts and the observance of the electric circuit law when solving the optimization problem allow for determining the actual value of the EPS flexibility during a considered time. [ABSTRACT FROM AUTHOR]

• A PHCA system can be incorporated with renewable sources such as wind and solar. • A thermodynamic and exergy model was developed to study a PHCA system performance. • Key parameters affecting the system performance were investigated and evaluated. • Exergy destruction for each system component was analysed and discussed. • Pump was identified as the most important component to improve the system efficiency. The Pumped-Hydro and Compressed-Air (PHCA) is a new energy storage system which can be coordinated with renewable energy sources such as wind and solar. In this paper, a comprehensive thermodynamic and exergy model is developed to study the thermal characteristics of a combined Pumped-Hydro and Compressed-Air (PHCA) energy storage system. The effect of key parameters, including storage pressure, pre-set pressure, air-compression mode and pump/hydroturbine efficiency on system performance is investigated. The results showed that an optimum pre-set pressure existed to maximize energy storage level for a specific storage pressure. The storage pressure also showed a large effect on the energy storage level and work output. As the storage pressure increased from 4 to 16 MPa, the energy storage level and work output increased remarkably. Furthermore, the performance of a PHCA system was largely influenced by the air compression/expansion mode in the energy storage vessel. The PHCA system stored 10% more energy through an isothermal compression process than that through an isentropic air compression process. It generated 14% more work output through an isothermal expansion process than that through an isentropic air expansion process. The exergy analyses showed that exergy destruction in pump was about 15% higher than that in hydroturbine. [ABSTRACT FROM AUTHOR]

In the revolution of green energy development, microgrids with renewable energy sources such as solar, wind and fuel cells are becoming a popular and effective way of controlling and managing these sources. On the other hand, owing to the intermittency and wide range of dynamic responses of renewable energy sources, battery energy-storage systems have become an integral feature of microgrids. Intelligent energy management and battery sizing are essential requirements in the microgrids to ensure the optimal use of the renewable sources and reduce conventional fuel utilization in such complex systems. This paper presents a novel approach to meet these requirements by using the grey wolf optimization (GWO) technique. The proposed algorithm is implemented for different scenarios, and the numerical simulation results are compared with other optimization methods including the genetic algorithm (GA), particle swarm optimization (PSO), the Bat algorithm (BA), and the improved bat algorithm (IBA). The proposed method (GWO) shows outstanding results and superior performance compared with other algorithms in terms of solution quality and computational efficiency. The numerical results show that the GWO with a smart utilization of battery energy storage (BES) helped to minimize the operational costs of microgrid by 33.185% in comparison with GA, PSO, BA and IBA. [ABSTRACT FROM AUTHOR]

Consumers conventionally adopt diesel generation to meet the energy needs where the grid connection is unreliable or unavailable. While electrification has provided these communities a variety of economic and social opportunities, diesel consumption has resulted in adverse costs and environmental pollution. Two technologies available to reduce the expense and emissions of diesel fuel reliance include dual fuel or hybrid diesel applications. The dual-fuel approach involves a supplementary gas fuel charge in support of reduced diesel fuel consumption. Hybrid applications involve the integration of renewable generation to displace diesel fuel consumption. This paper reviews the potential for hybrid dual-fuel applications, identifying engine flexibility as a major integration barrier. In comparing the flexibility of various dual-fuel technologies to operate dynamically, this paper presents a critical review across hydrogen, liquified petroleum gas (LPG), natural gas (NG) and blended hydrogen and NG derivatives. The results identify a range of approaches able to improve engine flexibility and thus reduce the cost and carbon intensity of diesel-fired internal combustion engines. At low load conditions, while NG and LPG exhibit similar performance, the use of hydrogen and hydrogen blends provide improved engine performance and response. Unfortunately, given the current cost of hydrogen fuel, significant commercial barriers exist to the adoption of hydrogen or hydrogen blended fuels. Despite this, this review indicates the potential of hydrogen-NG blends to offer additional flexibility in comparison to alternative dual-fuel technologies. This position is furthered considering near term cost targets associated with the development of a global green hydrogen industry, coupled with its ability to serve as a demand-side management approach within isolated power systems, one of the multiple future research themes. • The potential of dual fuel approach in renewable energy applications was assessed. • Different dual fuel technologies were compared over various conditions. • Dual fuel low load application was discussed to manage the variability of RE sources. • The ability of H 2 , NG and LPG dual fuel approaches operate at low load was compared. • EGR and Fuel Injection were effective methods to improve combustion performance. [ABSTRACT FROM AUTHOR]