Effects of Increasing Power Electronics on System Stability: Results from MIGRATE Questionnaire

Abstract

Power systems throughout the world are experiencing increasing levels of power electronics interfaced generation in their generation portfolio. As these devices have a significantly different dynamic behavior than conventional synchronous generators, it is expected that this trend will pose power system stability related challenges. This paper presents the results of a questionnaire conducted within the MIGRATE project. The aim of this questionnaire, to which more than 20 European transmission system operators (TSOs) responded, was to identify and prioritize these challenges. The TSOs identified challenges related to rotor angle stability (two), frequency stability (three), voltage stability (five), and power electronics interactions and resonances (two). In a follow-up survey, the TSOs were asked to rank the challenges based on their severity, probability of occurrence, and time of manifestation. The decrease of inertia was ranked the highest among the 11 issues. Additionally, the TSOs gave insight into current practices with regards to system monitoring and analysis. Based on the ranking, mitigation measures are currently being designed in order to facilitate an even higher amount of power electronics interfaced renewable energy sources in the power system.

Effiziente Modellierung von Windenergieanlagen mit doppelt gespeister Asynchronmaschine und Vollumrichter für Untersuchungen der Frequenzstabilität

“…Frequency stability studies are traditionally conducted using RMS simulations, which are capable of simulating much longer events and much larger grid areas compared to EMT simulations [14,[18][19][20]. The RMS wind turbine (WT) models used in frequency stability studies, which are designed based on fundamental machine and converter equations and are also known as quasi-stationary models in the literature, require smaller simulation time steps compared to the conventional active devices (i.e., synchronous generators and dynamic loads) due to comparatively smaller time constants of the converter controllers [6,10].…”

Analysis of Onshore Synthetic Inertia and Primary Control Reserve Contributions of Alternating Current-Side Meshed Offshore Grids with Voltage-Source Converter and Diode Rectifier Unit High-Voltage Direct Current Connections

“…With the increasing use of renewable energy sources and the coinciding decommissioning of conventional generation units to meet the European goals for reducing greenhouse gas emissions, a fundamental change in the electrical power system is taking place [1,2]. This change involves a decrease in inertia within the onshore grid, as conventional generation units usually involve synchronous generators with rotating masses, whereas renewable generation is connected by power electronic inverters instead [3,4]. Being directly related to frequency stability, the decrease in inertia is closely monitored by the European Network of Transmission System Operators (ENTSO-E) and, amongst others, addressed in the European Union (EU)-funded projects MIGRATE (Massive Integration of Power Electronic Devices) and RE-SERVE (Renewables in a Stable Electric Grid) [3][4][5][6][7].…”

Review of Small-Signal Converter-Driven Stability Issues in Power Systems

“…The slow-interaction converter-driven stability refers to the stability issues driven by the slow dynamic interactions between the slow outer control loops of converters and other slow-response components in power systems, typically around system fundamental frequency; while the fast-interaction converter-driven stability (also referred to as harmonic stability [26]) involves the problems caused by fast dynamic interactions between the fast inner control loop of converters and other fast-response components in power systems, typically in the range of hundreds of hertz to several kilohertz. The converter-driven instability may arise due to many different reasons, such as converter-interfaced generation (CIG) controls, grid strength, converter-interfaced loads (CIL), operating conditions, power transfer limits, and other similar factors [27,28]. For example, the fast control dynamics of the CIGs may result in rapid frequency changes or transiently distorted voltage/current waveforms, which may lead to the over-reaction of protections fitted to the inverters and cause system tripping [29].…”