This paper investigates how black-box representation of sub-systems in a larger small-signal state-space model influences the results from participation factor analysis. The results show that the value of individual participation factors associated with the states of a black-box sub-system on diagonalized form can be misleading. To avoid this issue, participation factor analysis involving a black-boxed sub-system should be based on aggregation by the complex sum of participation factors associated with the subsystem. The reason is that individual participation factors of the diagonalized sub-system can assume high values that do not reflect a physical interaction with other sub-systems. However, the individual participation factors of any transparent part of the system model can still be studied according to established conventional methods. These findings are obtained from, and demonstrated by, analysis of the small-signal dynamics in an offshore islanded AC grid with two HVDC converter terminals applying grid forming control and two equivalent grid-following converters representing separate wind farm clusters.

Accurate intraday solar irradiance forecasting is crucial for optimizing dispatch planning and electricity trading. For this purpose, we introduce a novel and effective approach that includes three distinguishing components from the literature: 1) the uncommon use of single-frame public camera imagery; 2) solar irradiance time series scaled with a proposed normalization step, which boosts performance; and 3) a lightweight multimodal model, called Solar Multimodal Transformer (SMT), that delivers accurate shortterm solar irradiance forecasting by combining images and scaled time series. Benchmarking against Solcast, a leading solar forecasting service provider, our model improved prediction accuracy by 25.95%. Our approach allows for easy adaptation to various camera specifications, offering broad applicability for real-world solar forecasting challenges.

Key operational and protection functions of power systems (e.g., optimal power flow scheduling and control, state estimation (SE), protection, and fault location) rely on the availability of models to represent the system’s behavior under different operating conditions. Power system models require knowledge of the components’ electrical parameters and the system topology. However, these data may be inaccurate for several reasons (e.g., inaccurate information of components datasheets and/or outdated topological information). The deployment of time synchronization in phasor measurement units (PMUs) and remote terminal units (RTUs) enables the collection of large datasets of synchronized measurements to infer power system models and learn associated power flow constraints. Within this context, this article presents a comprehensive review of measurement-based estimation methods for power flow models using time-synchronized measurements. It begins by exploring advancements in time dissemination technologies and the characterization of uncertainties in PMUs and instrument transformers (ITs), along with their implications for parameter estimation. This article then examines the power system parameter estimation problem, highlighting key techniques and methodologies. In the following, this article focuses on measurement models for state-independent power flow model estimation, including line parameters, admittance matrices, topology, and joint state-parameter estimation. Finally, this article discusses recent approaches for estimating state-dependent power flow models, with particular reference to linearized power flow approximations because of their large use in control applications.

The existing approaches to control electrical grids combine frequency and voltage controls at different time-scales. When applied in microgrids with stochastic distributed generation, grid quality of service problems may occur, such as under- or overvoltages as well as congestion of lines and transformers. The COMMELEC framework proposes to solve this compelling issue by performing explicit control of power flows with two novel strategies: 1) a common abstract model is used by resources to advertise their state in real time to a grid agent; and 2) subsystems can be aggregated into virtual devices that hide their internal complexity in order to ensure scalability. While the framework has already been published in the literature, in this paper, we present the first experimental validation of a practicable explicit power-flow primary control applied in a real-scale test-bed microgrid. We demonstrate how an explicit power-flow control solves the active and reactive power sharing problem in real time, easily allowing the microgrid to be dispatchable in real time (i.e., it is able to participate in energy markets) and capable of providing frequency support, while always maintaining quality of service.

We consider the problem of estimating the unobserved amount of photovoltaic (PV) generation and demand in a power distribution network starting from measurements of the aggregated power flow at the point of common coupling and local global horizontal irradiance (GHI). The estimation principle relies on modeling the PV generation as a function of the measured GHI, enabling the identification of PV production patterns in the aggregated power flow measurements. Four estimation algorithms are proposed: the first assumes that variability in the aggregated PV generation is given by variations of PV generation, the next two use a model of the demand to improve estimation performance, and the fourth assumes that, in a certain frequency range, the aggregated power flow is dominated by PV generation dynamics. These algorithms leverage irradiance transposition models to explore several azimuth/tilt configurations and explain PV generation patterns from multiple plants with nonuniform installation characteristics. Their estimation performance is compared and validated with measurements from a real-life setup including four houses with rooftop PV installations and battery systems for PV self-consumption.

This paper describes a first prototype harvesting the acoustic energy using electrochemical storage devices. In particular, the harvesting system is composed by an Electrochemical Double Layer Capacitors (EDLC) suitably coupled with an electroacoustic absorber by means of an AC/DC converter. The aims of the proposed work are i) to assess the technical feasibility to compensate the decay voltage via an acoustic harvester; and ii) to evaluate how such compensation can improve the performance of the targeted EDLC. Concerning the first aim, the experimental results show that the required sound pressures to charge the EDLC up to its nominal voltage range from 118 dB up to 122 dB (re. 20 μPa). The EDLC charging times range from couple of hours up to several hours. The charging powers range from few mW up to several tens of mW and the energy efficiency of the whole system ranges from 5% up to 35%. Concerning the second aim of the paper, further experimental results illustrate a non-negligible improvement of the capability of the EDLC to deliver high-pulsed currents. In particular, after compensating the EDLC decay voltage via the proposed acoustic harvester, the rise time required to deliver a high pulse current is even 170% lower than the one obtained without any previous decay voltage compensation. The associated current peak value and root mean square value are 20 % higher.

IEEE C37.118 is the current standard for synchrophasor measurements in power systems. It defines the measurement method and communication protocols for the entities in a synchrophasor network. The standard offers two different modes for client-server communication, but cannot be used unchanged over publish/subscribe communication architectures, whose major advantage is simplified and incremental integration of new applications. This work reviews the communication part of IEEE C37.118, and provides an adapter-based solution to easily connect and integrate entities in a synchrophasor network over a publish/subscribe communication architecture. The proposed adapters offer standard-compliant communication between the synchrophasor measurement network entities to facilitate the exchange of measurement data.

This paper proposes a new experimental investigation of the ageing mechanisms of supercapacitors. Starting from the main ageing mechanisms of these devices reported in the literature, the paper proposes a suitably developed procedure aimed at evaluating their ageing during combined life endurance and power cycling tests. In particular, the effect of the temperature (usually referred as life endurance) is evaluated in supercapacitors solicited with an a-priori defined power cycle. The effects of the temperature during the so-called recovering phase are also investigated. Each experimental finding is discussed by taking into account the phenomenon of the residual charge redistribution inside the supercapacitor electrodes.