Modern electricity grids are introducing more converter-connected renewable energy generators, which help combat climate change. These generators have zero carbon emissions of Scope 1 (instant emissions from burning fossil fuels) and have only Scope 3 carbon emissions (life-cycle emissions due to manufacturing, transportation, deployment and decommissioning). They can connect to the grid almost instantly, which is a great benefit for customers. However, most converter-connected generators lack the inherent grid stabilising functions of conventional generators, which have high inertia in their hardware (steam turbines powered by fossil fuels or nuclear power). As a result of this lower inertia, regular grid disturbances can lead to fast-changing grid frequency variations, potentially cascading to blackouts if uncontrolled. The goal of the modern energy systems is to combine the benefits of heterogeneous energy network with large penetration of renewable generators and highest possible stability of the grid at the level of the standard frequency 50Hz. We analyse frequency data of the UK grid and demonstrate how the machine learning tools help automate anomaly detection. We apply Bayesian change point analysis and tipping point analysis (early warning signals) to identify and align anomalies, which require additional processing for precise timing of the anomaly events [1]. We also apply clustering to more than 300 datasets of the UK frequency anomaly events and identify several types of such anomalies. Our results provide the initial grounds for automated preventive management of the grid stability under the increasing number of renewable generators in the national grid. The methodology is generic and can be applied to other types of datasets across Europe.References[1] Livina et al, Geoscientific Instrumentation, Methods and Data Systems 14, 541-564, 2025

Sub-synchronous oscillations pose a significant challenge in modern power systems, particularly in networks with high penetration of power electronic converters. While phasor measurement units (PMUs) are generally used for grid monitoring, their ability to detect sub-synchronous oscillations is being challenged. This paper discusses PMU limitations in measuring sub-synchronous oscillations, introducing a novel algorithm to detect their occurrence by leveraging PMU phasor data and rate of-change-of-frequency analysis to trigger high-resolution voltage waveform recordings. This approach enables direct comparison between PMU-reported events and raw waveform data, which paves the way to analysing discrepancies and limitations in PMU based detection. Key words. Measurement techniques, power grids, phasor measurement units, oscillations, power quality.

The increasing integration of converter interfaced generation is reshaping frequency dynamics in electric power systems, reducing the effectiveness of traditional system-wide inertia metrics. This paper emphasizes the need to revive the concept of local frequency response, which becomes increasingly relevant as frequency behavior varies significantly across the network following disturbances. A theoretical radial network model is used to illustrate how frequency deviations emerge and propagate across the system, depending on electrical proximity and system topology. A method for constructing rate-of-change-of-frequency maps is proposed to identify areas vulnerable to critical frequency excursions. Two case studies, one based on the Slovenian electric power system and another on a real incident in Great Britain, demonstrate the need to monitor and manage frequency behavior at the local level. The findings highlight the urgency of reviving local frequency response concepts in planning, monitoring, and control as power systems transition toward low-inertia operation.

As the share of converter-connected power generation increases, new frequency stability challenges have arisen due to declining inertia levels. Grid operators need more accurate visibility of inertia to maintain system reliability. Many researchers have developed new methods for inertia monitoring, however, there is currently no standard verification method. This paper presents a proposed verification approach for commercial inertia monitoring systems currently trialed in the British power system. The development of the approach based on grid operator requirements and the measurement challenges under noisy transient power system conditions are described.

The increase in the use of electric vehicles (EV) has caused a growth in EV chargers, which incorporate DC metering to bill consumers. These EV chargers can generate electrical disturbances superimposed on the DC that interfere with the metering if it has insufficient immunity to this DC power quality (PQ) phenomena. This paper describes the design of an analyser to measure DC PQ . The specifications and constraints of the DC PQ analyser are given, with a detailed plan of the instrument components and assembly. The paper also explains the measurement requirements for the validation of the analyser. It is necessary to measure the DC PQ in between EVs and their DC chargers to ensure that the DC metering standards such as IEC 62052-11 applied, are appropriate for the distortions present.

As power converters gain a pivotal role in driving the energy transition of power networks, new electrical phenomena are emerging in the grid. Amongst them, a new type of sub-synchronous oscillation has been identified as originating from the interaction of power converters connected to the grid. This paper discusses the detection and measurement of sub-synchronous oscillations along with the instrumentation requirements.

This work presents a novel measurement method to characterize long-term and short-term variations of the LV grid impedance from 20 kHz to 10 MHz with configurable time, frequency and amplitude resolutions. The characterization of the grid access impedance in this frequency range is vital for the design and development of NB-PLC and BB-PLC technologies. The measurement system is valid for in-home, indoor cable networks and for the harsh conditions of the LV distribution grid, where a large input dynamic range and strong protection mechanisms against high-amplitude impulsive noises are required. Its accuracy is evaluated by comparison to a precision impedance meter for a wide set of impedance values, obtaining a maximum deviation within ± 8%. First trials of the grid impedance sub-cycle variations caused by commercial appliances and for frequencies assigned to BB-PLC are also presented in this paper. The results demonstrate that the grid impedance is highly time-varying within the mains cycle, both in amplitude and phase. These first outcomes point at the need to evaluate the accumulative effects of sub-cycle variations in the LV distribution grid, so that equalization algorithms in the next BB-PLC technologies could be developed to overcome the impact of these fast variations.

The main objective of this work is to obtain an empirical relationship between the root-mean-square and the quasi-peak spectra of voltage recordings in the electrical grid, based on a statistical analysis of a set of on-field measurements for the CISPR Band A (9-150 kHz). The lack of a relationship between the weighting root-mean-square and quasi-peak detectors implies the impossibility of calculating quasi-peak (QP) spectra from root-mean-square (RMS) measurements. It is of great interest that quasi-peak values can be estimated by simple calculations from RMS values, so that comparison to compatibility levels could be applied.This work defines an empirical relationship between the statistical variation of instantaneous RMS values over time, the maximum RMS value of these instantaneous values and the QP output. This relationship is described in the form of a simple equation that can be applied to RMS provided by the RM-A method, specifically developed for the CISPR Band A.A method for the fast assessment of QP values from simple RMS receivers is proposed as a potential application of the numerical RMS-QP relationship. Both the numerical RMS-QP relationship and its application as a simple and fast assessment method are evaluated with disturbances recorded in the low voltage grid.

The IEC 61000-2-2 standard defines the compatibility levels to evaluate the conducted disturbances in the low voltage grid for the 2-150 kHz range. For frequencies 9-150 kHz, they are defined in terms of quasi peak values measured according to CISPR 16-1-1 standard, but no clear guidance is given on how to apply this standard to grid measurements. The definition of the method in CISPR 16-1-1 accepts a wide range of different imple-mentations, all of them fulfilling the compliance requirements. The reasons are that the standard does not propose a fixed implementation but a 'black-box' approach, and some of the proposed configuration values are non-normative and/or wide tolerances are allowed. In this context, some parameters have a pivotal role in the results provided by the method. The impact of variation of these parameters on the measurement results is addressed in this work. In particular, the accuracy requirements and the reproducibility issues of the standard are studied. For that purpose, a high number of different compliant implementations have been developed and the influence of different features of the CISPR 16-1-1 method on the results of these implementations is identified and analyzed. The results show that the wide tolerances allowed by the CISPR 16 specification impede the comparison of results provided by measuring receivers based on different implementations of the standard. Results of the study also show that reproducibility issues for the same input signal may be relevant and generate inconsistences. Moreover, a fixed specific configuration does not ensure that uncertainty issues are solved, as the technical approach used in the implementation of the damped meter has a strong influence on the outputs. An unambiguous guidance of digital implementation of the standard could fix these issues.

This study proposes a novel measurement method to assess the disturbances in the electrical grid for the CISPR Band A (9–150 kHz), as no normative grid measurement method for these frequencies exists yet. Compatibility levels (CL) in IEC 61000-2-2 in this frequency range are defined based on the CISPR 16-1-1 method using the quasi-peak (QP) detector. However, this method is not directly applicable for grid measurements as it was originally designed for laboratory conditions and for measuring radio disturbances and immunity. The method proposed in this article (Light-QP method) overcomes these limitations, along with lower complexity, computational burden, and memory requirements than CISPR 16-1-1. The Light-QP method uses a digital QP detector that processes root mean square (rms) values of spectral components, calculated by adapting the IEC 61000-4-7 standard to the CISPR Band A. The proposed Light-QP method is applied to real measurements from a low-voltage (LV) distribution grid and compared to the QP outputs from a digital implementation of the CISPR 16-1-1 method. The results are comparable and can be used for assessment against CL. The Light-QP method has been presented to IEC SC77A/WG9 for its potential inclusion as a normative measurement method in a new version of the IEC 61000-4-30 standard.

This article presents a strategy for the description of new test waveforms for static electricity meters to be included in international standards. The need of extending the existing standardization frame arises from several recent studies that have reported conducted electromagnetic interference problems of type-approved static electricity meters, resulting in significant errors in the measured electricity consumption. The proposed method is based on discrete wavelet transform and allows for a compact and parsimonious representation of test waveforms, suitable for inclusion in standards. Very few wavelet parameters are concentrating the relevant information to accurately reproduce all the characteristics that the meters need to be tested against. The same parsimonious description cannot be performed with the current practices based on Fourier transform methods since the new test signals need to be highly non-sinusoidal. The discrete wavelet transform is proposed as a more effective tool to sparsely describe the most relevant waveform features. The effect of different discrete wavelet transform decomposition settings on compactness and reconstruction accuracy is studied using suitable metrics. Finally, results from experimental validation with several different waveforms are presented to demonstrate that the error-inducing features can be preserved using only 0.1% of the original signal information.

Devices connected to the low-voltage power grid generate disturbances that can cause malfunctions and thermal stress in the equipment connected to the mains or interference on power line communications. Currently, there is no normative method to measure the disturbances in the low voltage grid for the CISPR Band A (9-150 kHz). The Annex C of IEC 61000-4-30 Ed. 3 standard suggests three non-normative measurement methods, one of them is the method described in Annex B of IEC 61000-4-7for the 2-9 kHz range. This paper describes a proposal to adapt this method to the CISPR Band A: the RM-A method. This method aims at obtaining results of similar amplitude, with a higher granularity in the time domain, and avoiding a high computational burden due to the broader frequency range. Moreover, a more accurate detection of high-level short impulsive disturbances is obtained. The performance of the RM-A method is evaluated using a data set of recordings from the low voltage grid. The proposed method has been presented to IEC SC77A/WG9 as a first stage of a more complex method, for its potential inclusions in the IEC 61000-4-30 Ed. 4.

During the last few years, the accuracy of static electricity meters (SEM) has been questioned. Significant metering deviations with respect to a reference meter have been observed at customer premises, and laboratory experimental tests results support such findings. The root cause of such errors remains unknown, as there are multiple elements that could affect the accuracy of electricity meters. Furthermore, standard compliant meters exposed to distorted signals may produce negligible, positive or negative relative error depending on the instrument design. Distorted current signals with fast amplitude transitions have produced the highest error in SEMs reported in the literature. In this paper, the accuracy of an energy metering Integrated Circuit (IC) is evaluated beyond the limits of the standards requirements employing a selection of distorted signals from the standards, real-world captured signals and a set of waveforms designed to test the IC under fast changing currents conditions, which are representative of the waveforms resulting from power electronic devices. The experimental results reveal an accuracy boundary imposed by Gibb’s phenomenon for fast changing current signals and a strong relationship between the IC’s measurement error and two key parameters of the measured waveform: signal slope and phase angle. This paper therefore provides a methodology for the comprehensive analysis of SEMs in future power systems which are dominated with power electronic-controlled electrical demand and contributes to the search for the root cause of error in SEMs exposed to distorted waveforms.

This article describes a method of isolating high-resolution digitizers that have a common ground between channels.Isolation enables the digitizers to be used simultaneously to measure multiple points in a circuit without shortcircuiting via the common ground.The isolators, when used in a switch formation, provide a method to cancel out the phase angle errors when measuring the difference in phase angles between channels.Various tests are reported, which assess the performance of the isolator over its operating range.These include temperature coefficient, linearity, gain stability commonmode rejection, and crosstalk.

Based on user expectations and requirements, this article discusses three use cases (UCs) for measurements of power system frequency and rate-of-change-of-frequency (ROCOF) measurements, specifying accuracy and latency requirement for each UC. Furthermore, a set of realistic test conditions are proposed, extending those of the present IEC/IEEE 60255-118-1 standard, to ensure ROCOF measuring instruments are adequately tested on their suitability for reliable ROCOF measurements in power systems. Target worst case ROCOF errors (RFEs) are given for each test waveform and UC. Several published ROCOF algorithms are tested using the proposed test conditions. A selection of the test results is reported and compared against the target RFEs. The results show that the defined tests are indeed helpful in evaluating the ROCOF algorithms, and furthermore that the algorithms can be designed to meet all the requirements on RFEs for the tests proposed in this article.

This paper describes a method of isolating high resolution digitizers which have a common ground for different channels, so the digitizers can be used simultaneously with current shunts and resistive voltage dividers in wideband power meters. The isolators have sufficient amplitude stability up to 100 kHz to be used in static meter testing. The isolators when used in a switch formation provide a method to cancel out the phase angle errors when trying to measure the difference in phase angles between channels.

A framework for the comparison of measurement methods of conducted emissions in the frequency range 2-150 kHz is presented. In addition to present non-normative methods published by the IEC, alternative approaches in the literature are considered. Furthermore, test signals and key metrics are described. The comparison results will provide a baseline for specification of a new normative method for power grid measurements.

This paper describes a new method for measurements of signals in the 2–150 kHz frequency range, as required to support the regulation of conducted emissions on the power grid. The digital method is based on heterodyning, decimation and multi resolution analysis.

Recent observations of significant errors in static electricity meter readings have created a need for specification of new standard immunity test waveforms. This paper provides an overview of ongoing signal analysis work towards parsimonious specification of suitable test waveforms including candidate methods for signal representation, feature extraction and feature selection.