EMRP-ENG52: Measurement tools for smart grid stability and quality (SmartGrid II)

• Forschungsstelle: METAS
• Projektnummer: F-5213.30036
• Projekttitel Englisch: EMRP-ENG52: Measurement tools for smart grid stability and quality (SmartGrid II)

Schlüsselwörter (Englisch)

Smart Grids, Power Quality, Phasor Measurement Units (PMU), Wide-Area Measurement Systems (WAMS),
Synchrophasor, Renewables, Electricity Distribution, Electricity Transmission

Kurzbeschreibung (Englisch)

Smart Grids are primarily required to dynamically balance variable renewable supply with variable demand to achieve grid stability and prevent a degradation of power quality (PQ) that would otherwise lead to cascading failures and power blackouts.
Network operators need tools to measure the quality and stability of the electricity supply under the challenging dynamic conditions prevalent in networks with a high penetration of distributed renewable generation. Wide-area measurement systems using phasor measurement units (PMU) are increasingly seen as the “life-support monitors” for Smart Grids and they present many new opportunities to understand the complex dynamics of these networks. However, unless properly formulated and deployed, these new measurement techniques have many potential pitfalls that will give rise to misleading results that could ultimately undermine, rather than boost confidence in future-networks.
This joint research project will engage with this rapidly developing technology and implement a complete metrology framework for PMUs. In particular, addressing the exacting calibration requirements for PMUs and associated transducers when used to monitor the stability of distribution networks where very small phase changes are critical. Furthermore, new synchronized grid measurement techniques are needed to determine the propagation of PQ in networks, locate significant sources of PQ disturbance and measure network impedance, all of which are essential to Smart Grid planning and management.

This project is part of the European Metrology Research Programme (EMRP, http://www.euramet.org/index.php?id=emrp); it is partly funded by the European Union on the basis of Decision No 912/2009/EC.

A more detailed description of the project may be found in the encloed publishable summary.

Zugehörige Dokumente

• ENG52_Publishable_JRP_Summary.pdf [PDF] 148 kB

Projektziele (Englisch)

The aim of this JRP is to develop, demonstrate and validate new measurement tools for the management of Smart Grid operational stability and power quality. Results and analysis of on-site measurements during the JRP will provide vital research information to grid designers, planners and standards bodies. Beyond the JRP the tools will be used by network operators for the management future Smart Grids.
The common theme to these tools is the use of multiple digitising instruments placed at geographically remote locations around an electricity grid. These instruments are time-synchronised to form a wide-area measurement system using GPS. Specifically the JRP will develop new wide-area related technical objectives aimed at the following:
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• PQ Propagation (WP1). Determination of PQ propagation mechanisms associated with a selection of disturbance sources in a variety of distribution and transmission networks. The results will be reconciled against network topology, drawing conclusions to support future network planning and standardisation.
• PQ Disturbance and Fault Location (WP1). Amplitude and phase measurements for multiple GPS synchronised instruments will be used to determine power flows associated with major PQ disturbance / faults and their locations will be estimated.
• Network impedance and system resonances (WP3). Wide-area measurements and the analysis of system impedance and resonances in HV/MV/LV networks. Results will be evaluated against network design data and models.
• PMUs in Distribution Networks (WP2). Selection, comparison and validation of new PMU algorithms suitable for use in LV and MV distribution networks. These networks are characterised by smaller distances and hence require higher phase sensitivity whilst at the same time accounting for a higher level of PQ disturbances.
• Dynamic calibration of PMUs (WP2). Develop extensions to a laboratory PMU calibrator to provide new calibration support for the dynamic performance of PMUs as proposed in IEEE standard C37-118.1 (2011).
• On-Site Calibration of PMUs (WP2). Undertake on-site measurements using reference PMUs, suitably modified to calibrate/verify the operation under realistic conditions including PQ disturbances.
• PMU/PQ Transducer Characterisation (WP4). Develop/apply wideband evaluation facilities for transducers and optimise non-invasive transducers specifically applied to the PMU/PQ measurement chain.
• Digitised Waveform Corrections (WP4). Develop and evaluate signal processing methods to apply transducer frequency response corrections to sampled complex wave shapes typically present in PMU/PQ measurements. Reconcile the propagation of transducer uncertainties through complex PQ and PMU algorithms.
• Standardisation Input (WP5). Provide metrology input and pre-normative research to the evolution of International (CEN, CENELEC, IEC, IEEE) standards concerning PMUs for network controllability and PQ in a Smart Grid context.

METAS is involved in WP1 and WP2.

Abstract (Englisch)

The aim of this project was the continuation of the work undertaken during the project Smart Grid 1. In this project, a PMU calibrator was developed which proved to be capable to test PMUs for static conditions according to the standard IEEE C37.118. The specific goals for this project consisted of:

• extending the performances of the calibrator for dynamic tests,
• improving the accuracy for the testing need of future PMUs used in distribution networks,
• developing a software allowing the automatic testing of PMUs.

The PMU calibrator is now operational and the main objectives of this project have been achieved. A flexible software enables the automatic generation of waveforms and the handling of the large amount of data required for the testing of PMUs. This includes the fitting of complex signals and the estimation of the corresponding phasors. Additionally, the software is also capable to automatically generate test reports. With the exception of the latency test, the PMU calibrator is now capable to rapidly and fully test a PMU against the IEEE C37.118a standard.

While the PMU calibrator is now operational, the demonstration of its full performance as well as its incertitude still requires some effort. This should, however, be considered as a normal improvement path for such a system. Some of the concepts developed in this project such as use of UTC-CH as time source and of active calibration, will also require some additional effort in order to achieve the performances required for the testing of advanced PMUs that will be used in active distribution networks (smart grids).

Umsetzung und Anwendungen (Englisch)

The PMU calibrator developed in this project has already proven itself as a valuable asset for the Power and Energy Laboratory at METAS. The launch of first power quality certifications would have not been possible without this PMU calibrator. Several of the tests outlined in the standard IEC 62586-2 (PQ certification) call for special waveforms, UTC synchronised signals and test scenarios that cannot be generated by commercially available instrumentation.

The key feature of the PMU calibrator is its flexibility in creating test scripts demanding complex signals whose relation with UTC is known.

Publikationen / Ergebnisse (Englisch)

U. Pogliano, J.P. Braun, S. Siegenthaler, B. Trinchera, D. Serazio, "Design of equalizers for a PMU calibrator," IEEE Transaction on Instrumentation and Measurement.

G. Frigo, D. Colangelo, A.Deviskadic, J.P. Braun, M. Paolone, "Metrological characterization of a high-accuracy calibration system for PMUs operating in distribution networks," IEEE Transaction on Instrumentation and Measurement.

J.P. Braun, C. Mester, M.O. André, "Requirements for an advanced PMU calibrator," in Proc. CPEM Digest, Ottawa, Canada, Jul. 2016

J.P. Braun, S. Siegenthaler, "The calibration of static and dynamic performance of PMUs," Congrès International de Métrologie, Paris, France, Sept. 2015

D. Colangeo, L. Zanni, Marco Pignati, P. Romano, M. Paolone, J.P. Braun, L.G. Bernier, "Architecture and characterization of a calibrator for PMUs operation in power distribution systems," IEEE PowerTech Conference, Eindhoven, Netherlands, July 2015

J.P. Braun, S. Siegenthaler, "Calibration of PMUs with a reference grade calibrator," in Proc. CPEM Digest, Rio de Janeiro, Brazil, Jul. 2014