Islanding detection with universal grid-forming inverter-based generation

One major concern of commonly proposed grid-forming (GFM) inverter-based resources (IBRs) has been the unintentional islanding, because the variables that are typically used for islanding detection of GFMs are different than those traditionally used with grid-following (GFL) IBRs. Therefore, this paper studies the effect of recently proposed new universal frequency-locked-loop (U-FLL) -based GFM synchronization method on islanding detection with different passive methods like voltage vector shift, positive sequence voltage angle difference, voltage unbalance and voltage total harmonic distortion. The PSCAD simulations are done with 100 % IBR-based system as well as with hybrid power system including IBR-based distributed energy resources (DER) and synchronous generation (SG). Based on the simulations it can be concluded that the recently proposed universal U-FLL GFM method does not risk the operation of the traditional passive islanding detection schemes unlike some other commonly proposed GFM control methods.©2023 IET. This paper is a postprint of a paper submitted to and accepted for publication in 27th International Conference on Electricity Distribution (CIRED 2023) and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at the IET Digital Library.fi=vertaisarvioitu|en=peerReviewed

Impedance-compensated grid synchronisation for extending the stability range of weak grids with voltage source converters

This paper demonstrates how the range of stable power transfer in weak grids with voltage source converters (VSCs) can be extended by modifying the grid synchronisation mechanism of a conventional synchronous reference frame phase locked loop (PLL). By introducing an impedance-conditioning term in the PLL, the VSC control system can be virtually synchronised to a stronger point in the grid to counteract the instability effects caused by high grid impedance. To verify the effectiveness of the proposed approach, the maximum static power transfer capability and the small-signal stability range of a system with a VSC HVDC terminal connected to a weak grid are calculated from an analytical model with different levels of impedance-conditioning in the PLL. Such calculations are presented for two different configurations of the VSC control system, showing how both the static power transfer capability and the small-signal stability range can be significantly improved. The validity of the stability assessment is verified by time-domain simulations in the Matlab/Simulink environment.Peer ReviewedPostprint (published version

Security-constrained dispatch with controllable loads for integrating stochastic wind energy

This paper presents a bi-level consumer-utility optimization model to schedule an energy consumption pattern of controllable loads in the face of a time varying price function depending on system conditions and market operations. The controllable loads are classified into three types based on their natures and operating characteristics for an upper-level consumer's problem. To formulate the stochastic wind generators, a security-constrained optimal power flow (SCOPF) model is proposed for a lower-level utility's problem to consider various wind power scenarios. We then convert the bi-level model into a single-level of mathematical program with equilibrium constraints' (MPECs) problem to obtain the optimal load scheduling results. Finally, a simple case study is conducted to demonstrate the feasibility of the method. © 2012 IEEE.published_or_final_versio

An extended Kalman filter approach for accurate instantaneous dynamic phasor estimation

This paper proposes the application of a non-linear Extended Kalman Filter (EKF) for accurate instantaneous dynamic phasor estimation. An EKF-based algorithm is proposed to better adapt to the dynamic measurement requirements and to provide real-time tracking of the fundamental harmonic components and power system frequencies. This method is evaluated using dynamic compliance tests defined in the IEEE C37.118.1-2011 synchrophasor measurement standard, providing promising results in phasor and frequency estimation, compliant with the accuracy required in the case of off-nominal frequency, amplitude and phase angle modulations, frequency ramps, and step changes in magnitude and phase angle. An important additional feature of the method is its capability for real-time detection of transient disturbances in voltage or current waveforms using the residual of the filter, which enables flagging of the estimation for suitable processing

Smart Energy and Intelligent Transportation Systems

With the Internet of Things and various information and communication technologies, a city can manage its assets in a smarter way, constituting the urban development vision of a smart city. This facilitates a more efficient use of physical infrastructure and encourages citizen participation. Smart energy and smart mobility are among the key aspects of the smart city, in which the electric vehicle (EV) is believed to take a key role. EVs are powered by various energy sources or the electricity grid. With proper scheduling, a large fleet of EVs can be charged from charging stations and parking infrastructures. Although the battery capacity of a single EV is small, an aggregation of EVs can perform as a significant power source or load, constituting a vehicle-to-grid (V2G) system. Besides acquiring energy from the grid, in V2G, EVs can also support the grid by providing various demand response and auxiliary services. Thanks to this, we can reduce our reliance on fossil fuels and utilize the renewable energy more effectively. This Special Issue “Smart Energy and Intelligent Transportation Systems” addresses existing knowledge gaps and advances smart energy and mobility. It consists of five peer-reviewed papers that cover a range of subjects and applications related to smart energy and transportation