Load forecasting has always been an important part in the planning and operation of electric utilities, i.e., both transmission and distribution companies. With technological advancement, change in economic condition and many other factors (to be discussed in this work), load forecasting is becoming more important. The forecast affects as well as gets affected because of the load impacting factors and actions taken in different time horizons. However, due to its stochastic and uncertainty characteristics, it has been one challenging problem for electrical utilities to accurately forecast future load demand. This paper aims at reviewing the different load forecasting techniques developed for the mid-and long-term horizons of electrical power systems. Since there has never been an explicit literature study of the various forecasting techniques for mid-and long-term horizons, this paper reviews techniques for each of the forecasting horizons, citing various methodologies developed so far supported by published literature. The study is concluded with discussion on future research directions.

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Future power systems will contain more converterbased generation, among which voltage-sourced converter VSC-HVDC connected offshore wind power plants (WPP). Their interaction with the onshore system influences power system dynamics in the transient stability time-frame. The respective protection and control methods which cause this interaction must be taken into account in grid-integration studies performed today.This paper gives insight about the effect of typically required fault ride through (FRT) and post-FRT measures of VSC-HVDC connected offshore WPPs on the combined AC and HVDC system dynamics. Several important sensitivities are addressed, among which 1) FRT implementation, 2) the post-fault active power recovery rates, 3) the AC network dynamic characteristics, and 4) the HVDC topology.The analysis is first performed as a proof of concept on a small benchmark system, and subsequently generalized to a realistic dynamic model of the future Northwestern European power system. The results of this paper can be used as reference for understanding the effects of large-scale VSC-HVDC connected offshore WPPs on the stability of the onshore interconnected power systems.

High penetration of power electronic interfaced generation, like wind power, has an essential impact on the inertia of the interconnected power system. It can pose a significant threat to the frequency stability. This paper introduces the notion of the key performance indicator (KPI) and illustrates its application on large scale power systems, including Fast Frequency Response (FFR) and a high share of wind power, to measure the possible distance to the frequency stability limit. The proposed KPI estimates the change of frequency performance (e,g., ROCOF, NADIR) in the frequency containment period. The effect of FFR is analyzed by introducing a droop based controller for wind power plants. The FFR controller responds to a drop in grid frequency with a temporary increase of the wind active power. The proposed KPI maps a change in key system variables (e.g., system kinetic energy, aggregated generation output) onto the change of frequency performance. A comprehensive analysis using DIgSILENT, Matlab, and Python is performed for GB reduced size system. According to the obtained results, the FFR capability of wind generator leads to improvements of NADIR especially in cases with high penetration levels of wind power. The proposed KPI is a valuable tool for the frequency stability assessment in power system planning studies. It can be determined based on off-line simulations, and it can assist the system operators for frequency stability assessment in intra-day operational planning.

This paper examines the prospect of PEM (Proton Exchange Membrane) electrolyzers and fuel cells to partake in European electrical ancillary services markets. First, the current framework of ancillary services is reviewed and discussed, emphasizing the ongoing European harmonization plans for future frequency balancing markets. Next, the technical characteristics of PEM hydrogen technologies and their potential uses within the electrical power system are discussed to evaluate their adequacy to the requirements of ancillary services markets. Last, a case study based on a realistic representation of the transmission grid in the north of the Netherlands for the year 2030 is presented. The main goal of this case study is to ascertain the effectiveness of PEM electrolyzers and fuel cells for the provision of primary frequency reserves. Dynamic generic models suitable for grid simulations are developed for both technologies, including the required controllers to enable participation in ancillary services markets. The obtained results show that PEM hydrogen technologies can improve the frequency response when compared to the procurement with synchronous generators of the same reserve value. Moreover, the fast dynamics of PEM electrolyzers and fuel cells can help mitigate the negative effects attributed to the reduction of inertia in the system.

Electrical power system monitoring, protection, operation, and control schemes are undergoing significant changes towards the next generation fully automated, resilient, and self-healing grids. At present there still exists a lack of available user-friendly tools for the Synchronized Measurement Technology supported application design. This paper presents a Synchro-measurement Application Development Framework (SADF) to promote a simplified design and thorough validation of synchro-measurement (IEEE Std. C37.118.2-2011) supported user-defined applications under realistic conditions. The proposed SADF supports online receiving of a Phasor Measurement Unit (PMU) or Phasor Data Concentrator (PDC) provided data stream and enables simultaneous use of processed machine-readable synchro-measurements in advanced user-defined applications. This paper fills the scientific gap between the IEEE Std. C37.118.2-2011 specifications and its implementation by proposing a novel robust communication technique and efficient synchro-measurement data parsing methodology. As a proof-of-concept, the proposed SADF is implemented as a novel open-source MATLAB library. Combining this library with MATLAB's signal processing and visualization functions allows mastering the design and validation of complex Wide Area Monitoring, Protection, and Control applications as well as PMU/PDC performance and compliance verification. Finally, the paper verifies the proposed library against the standard specifications, assesses its interoperability and performance via a cyber-physical simulation platform, and presents online voltage magnitude monitoring as an example application.

In an electric power system, slow coherency can be applied to identify groups of the generating units, the rotors of which are swinging together against each other at approximately the same oscillatory frequencies of inter-area modes. This serves as a prerequisite-step of several emergency control schemes to identify power system control areas and improve transient stability. In this paper, slow coherent generators are grouped based on the direction and the strength of electromechanical coupling between different generators. The proposed algorithm performs low-pass filtering of generator frequency measurements. It adaptively determines the minimal number of the measurements to be processed in an observation window, and performs data selectivity to prevent mixing of interfering coherency indices. Finally, it adaptively tracks grouping changes of slow coherent generators and determines a finite number of groups for an improved affinity propagation clustering. The proposed algorithm is implemented as an online MATLAB program and verified in real-time using RTDS power system simulator with the integration of actual synchronized measurement technology components as hardware-in-the-loop. The obtained results demonstrate the effectiveness of the proposed algorithm for robust and near real-time identification of grouping changes of slow coherent generators during the quasi-steady-state and electromechanical transient period following a disturbance. where he was involved in modeling SF6 circuit breakers. His current research interests include future power systems, large-scale power system transients, intelligent protection for future power systems, and wide-area monitoring and protection. Prof. Popov is a member of CIGRE. He has actively participated in WG C4.502 and WG A2/C4.39. He was a recipient of the IEEE PES Prize Paper Award and the IEEE Switchgear Committee Award in 2011. He is an Associate Editor of the International Journal of Electric Power and Energy Systems. Mart A. M. M. van der Meijden (M'10) received the M.Sc. degree (cum laude) in electrical engineering from the Eindhoven University of Technology, Eindhoven, The Netherlands, in 1981.He is leading research programs on intelligent electrical power grids, reliable, and large-scale integration of renewable (wind and solar) energy sources in the European electrical power systems and advanced grid concepts. He has more than 30 years of working experience in the field of process automation and the transmission and the distribution of gas, district heating, and electricity. Since 2003, he has been with TenneT TSO, Arnhem, The Netherlands, Europe's first cross-border grid operator for electricity, where he is the Manager of Research and Development/Innovation and was responsible for the development of the TenneT long-term vision on the electrical transmission system. He has been a Full Professor (part-time) with the

Hydrogen as an energy carrier holds promising potential for future power systems. An excess of electrical power from renewables can be stored as hydrogen, which can be used at a later moment by industries, households or the transportation system. The stability of the power system could also benefit from electrolysers as these have the potential to participate in frequency and voltage support. Although some electrical models of small electrolysers exist, practical models of large electrolysers have not been described in literature yet. In this publication, a generic electrolyser model is developed in RSCAD, to be used in real-time simulations on the Real-Time Digital Simulator (RTDS). This model has been validated against field measurements of a 1-MW pilot electrolyser installed in the northern part of the Netherlands. To study the impact of electrolysers on power system stability, various simulations have been performed. These simulations show that electrolysers have a positive effect on frequency stability, as electrolysers are able to respond faster to frequency deviations than conventional generators.