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Abstract The analysis of power systems with a significant share of renewable generation using probabilistic tools is essential to appropriately consider the impact that the variability and intermittency of the renewable generation has on the grid. This paper provides a critical assessment and classification of the available probabilistic computational methods that have been applied to power system stability assessment (including small and large disturbance angular stability, voltage and frequency stability). A probabilistic analysis framework with a state-of-the-art review of the existing literature in the area is presented comprising of a review of (i) input variable modelling, (ii) computational methods and (iii) presentation techniques for the output/results. The most widely used probabilistic methods in power system studies are presented with their specific application areas, advantages, and disadvantages. The purpose of this overview, classification, and assessment of the existing methods is to identify the most appropriate probabilistic methods to be used in their current forms, or suitably modified, for different types of stability studies of power systems containing renewable generation. Highlights • Uncertainty modelling techniques for independent variables. • Uncertainty modelling techniques for correlated variables. • Probabilistic techniques applied to power system stability. • Identification of efficient computational techniques. • Future research needs in this area. [ABSTRACT FROM AUTHOR]

This paper evaluates a number of game theoretic (GT) approaches with the aim of assessing their suitability to identify the most influential parameters affecting the small-disturbance stability of a power system. Identification of the most influential parameters affecting system stability will facilitate cost-effective operation and control of a power system in general as it would require limited network monitoring, control and modelling effort by system operators and stakeholders. After identifying the most influential parameters the financial and human resources could be adequately prioritised and deployed to solve or prevent power system stability problems. A priority ranking procedure based on a GT approach has the advantage, compared to other techniques, of considering simultaneously the effect of individual and all possible combinatorial effects of the uncertain parameters (or players in a game context). In this study, the most influential players have been identified through a multi-level approach considering the power flow in the network (by optimal power flow), small disturbance stability aspects (by modal analysis), rational behavior of individual players (by a sensitivity technique) and formation of groups between players (by cooperative game theory). Various GT approaches have been considered namely Shapley Value, Aumann Shapley, Nucleolus, and τ -value approach in order to compare and assess their suitability for power system applications. The results are illustrated using two test networks and considering several approaches of sensitivity analysis and different degrees of variability in the considered uncertainties. [ABSTRACT FROM AUTHOR]

The decarbonisation of heat supply will play a critical role in meeting the emissions reduction target. There is, however, great uncertainty associated with the achievable levels of heat decarbonisation and the optimal heat technology mix, which can have serious implications for the future electricity and gas demand. This work employs an integrated gas, electricity and heat supply model to quantify the impacts of heat decarbonisation pathways on the future electricity and gas demand. A case study in the Great Britain is performed considering two heat decarbonisation scenarios in 2050: one is the predominantly electrified heat supply and the other is the predominantly hydrogen-based heat supply. The electricity demand becomes more volatile in the electrified heat scenario as the peak surges to 107.3 GW compared to 51.1 GW in the 2018 reference scenario, while the peak in hydrogen-based heat scenario is 78.4 GW. The peak gas demand declines from 247.6 GW for 2018 to 81.7 GW for electrified heat scenario and to 85.1 GW for hydrogen-based heat scenario, confirming that the seasonality associated with heat demand is shifting away from the gas network and towards electricity network. Moreover, a sensitivity analysis shows that the future electricity demand is highly sensitive to parameters such as relative heat demand, coefficient of performance of air source heat pumps and share of electricity in hydrogen production. Finally, the application of a load shifting strategy demonstrates that demand-side flexibility has the potential to maintain the electricity system balance and minimise the generation and network infrastructure requirements arising from heat electrification. While the case study presented in this paper is based on the Great Britain, the findings regarding the future electricity and gas demand are relevant for the global energy transition. • Integrated operation of gas, electricity and heat supply systems is modelled. • Impacts of heat decarbonisation on GB electricity and gas demand are quantified. • Sensitivity of future electricity demand to input uncertainties is investigated. • Role of flexibility in maintaining the electricity balance is demonstrated. [ABSTRACT FROM AUTHOR]

• A probabilistic multi-stability operational boundary assessment based on frequency, large-disturbance rotor angle, small-disturbance rotor angle, and voltage stability for varying renewable energy source penetration levels and loading conditions was investigated and established. • Establishing system's operational boundary from a singular stability type is dangerous as the established operational boundary from each stability type is very different. • The established multi-stability operational boundary is heavily influenced by frequency and large-signal disturbance rotor angle stability. • A significant improvement in the system's operational stability boundaries occur when the VSC-HVDC's ability to independently control active and reactive power via V DC - Q control is fully utilized. This paper presents a framework for defining multi-stability operational boundaries of power systems under varying penetration levels of power electronic interfaced generation and uncertain system's loading. Boundaries are established considering the small-disturbance and large-disturbance rotor angle stability, as well as the frequency and voltage stability of the system. Estimating system's operational boundary from multi-stability perspectives will provide invaluable information on how to best operate the system and how to mitigate certain condition that leads to instability especially in the current deregulated market and high penetration of power electronic interfaced generations. A singular stability assessment and its subsequent operational boundary may be valid only for a specific stability study and those may not be true for other types of stability. This paper illustrates the proposed framework in a modified New England Test System using a probabilistic approach. The impact of these varying loading conditions and renewable energy sources penetration levels are quantified on a per -stability-type basis and then aggregated into the multi-stability perspective. The established multi-stability operational boundary is heavily influenced by the frequency and large-signal disturbance rotor angle stability. A significant improvement in the system's operational stability boundaries, particularly for voltage stability and small disturbance rotor angle stability, occur when the voltage source converter high voltage direct current's ability to independently control active and reactive power via V DC - Q control is fully utilized. [ABSTRACT FROM AUTHOR]

• Updates nonlinear bifurcation analysis for voltage stability in modern power system. • Proposes new loadability boundary with the consideration of multiple bifurcations. • Develops new optimization framework to identify the system shortest loading margin. • Improves the system loading margin in control space within the proposed framework. The introduction of large numbers of power electronic converters along with increasing load demand will create voltage stability issues in future power systems. Most present analysis methodologies neglect the non-linearities within these systems. Bifurcation analysis is an increasingly popular method which not only incorporates system non-linearities, but also efficiently provides information about the system trajectory towards multiple instability mechanisms. This paper develops a new concept of combined system loadability with the consideration of saddle-node bifurcations (SNB), limit-induced bifurcations (LIB), and Hopf bifurcations (HB) simultaneously. These concepts have shown great promise in analyzing complex, multi-origin stability phenomena which are starting to appear in power systems and other areas, and are difficult to study using other methods. An optimization approach is applied to identify the system maximum loadability with these different types of bifurcation points which have not previously been considered at the same time. This creates a new system loadability boundary concept consisting of multiple types of bifurcation which is more representative of the actual power system limit boundary. By maximizing the shortest distance to the composite loadability boundary, the system loading margin is increased. Three illustrative systems are used to verify the proposed methodologies. [ABSTRACT FROM AUTHOR]

• A new index indicates the locations where the dynamic HVDC model is required. • The index quantifies mode shape differences between different HVDC modelling. • Mode shape changes indicate errors in damping ratios between different HVDC models. • Higher performance and reliability of the results compared to simple error methods. This paper presents a new measure that can be used to identify the locations where high levels of HVDC modelling can be simplified while maintaining the accuracy of the small-signal stability results. Low-frequency inter-area oscillations have posed a major issue to power system operations and stability, for example by reducing the maximum power transfer on tie lines connected between different regions or causing cascading failure due to ever-growing oscillations. In modern power systems, a significant number of High Voltage Direct Current (HVDC) systems are connected to power networks. An appropriate level of HVDC modelling is required in order to obtain accurate small-signal stability results in multi-infeed HVDC systems. Although accurate results can be obtained by using complex modelling details, this can be prohibitively computationally expensive due to increasing simulation time. In this paper, different levels of modelling fidelity for HVDC systems are investigated in order to establish the impact of the included HVDC system dynamics on small-signal stability. It is shown that some dynamic HVDC modelling, particularly LCC-HVDC and VSC-HVDC with P-Q control, can be replaced by simplified models in order to reduce the simulation time and model complexity while maintaining the accuracy of small-signal stability results. Furthermore, a method to identify which HVDC systems require detailed modelling based on the quantification of changes to critical mode shapes is developed. [ABSTRACT FROM AUTHOR]

• A generalized framework for transient stability assessment. • Practical for power systems with uncertainties. • Useful in development of probabilistic transient stability assessment frameworks. • Easy to implement on existing practical computational network models. This paper introduces a method for the identification of transient stability boundaries in power systems with multidimensional uncertainties. This method uses a parametric space rather than the state-space to identify the critical operating states. First, different transient stability indices are used to map the state-space of system into the index-specific parametric spaces. Then, these index-specific parametric spaces are characterized to identify their practicality and effectiveness to reflect the system's state-space information accurately and to quantify uncertainties. Finally, the transient stability boundaries are identified using the index-specific parametric spaces considering multidimensional uncertainties. The indices studied in this paper are on basis of rotor-angle difference, transient kinetic energy, and transient potential energy. This method is verified using a 16-machine, 68-bus computer model of the New England Test System and the New York Power System in MATLAB and DigSILENT environments. The uncertainty in this paper is represented in up to 4-dimensions and is modeled in form of loading conditions and generation dispatch uncertainties. This method is further applicable to higher dimensions and other forms of uncertainties and has the utility for probabilistic studies and predictive analytics. [ABSTRACT FROM AUTHOR]

• Special issue on control interactions in power electronic converter dominated power systems. • The Special Issue covered the latest research results on the control interactions. • It covered control interaction mechanism, modeling, analysis and control methods. Guest Editorial. [ABSTRACT FROM AUTHOR]

• Brief summary of the Special Issue on Recent Advancements in Electric Power System Development Planning with High-Penetration of Renewable Energy Resources and Dynamic Loads. • Review of the papers included in this special issue. • Viewpoint of the Guest Editorial Board on the present and future areas of research in Power System Planning. [ABSTRACT FROM AUTHOR]