2021 September – Europe Energy Climate book, grid stability and SCADA

InnoDC’s researchers have been publishing more work, summarised below. Click on the Journals page for the full list of specialist articles.

State Estimation for Hybrid VSC Based HVDC/AC: Unified Bad Data Detection Integrated with Gaussian Mixture Model.  IEEE Access. 

Authors: Motaz Ayiad, Helder Leite, Hugo Martins

Supervisory control and data acquisition (SCADA) systems have evolved to support intensive low-carbon technology integration, such as solar and wind power plants.  A rising trend is for these renewable energy resources to use high voltage direct current (HVDC) technology to transmit power from generation to distribution, instead of alternating current (AC). Consequently, HVAC/DC grids have emerged, creating the need for an enhanced SCADA.

Motaz Ayiad’s work focuses on one of SCADA’s toolboxes, the state estimator, which provides an accurate observation of the power network states (voltage magnitudes and phase angles).  The paper proposes an algorithm that deals with AC and DC grids simultaneously, known as a ‘unified Weighted Least Squares state estimation’ algorithm.  It couples both grids through a mathematical model of Voltage Source Converters, presented as power and voltage couplings.  In addition, the paper presents an advanced bad data detector that improves the algorithm’s robustness and reduces the total computational demand. The detector combines a traditional method, ‘the largest normalized residual’ with another, ‘the Gaussian mixture model’.  

The work was simulated on a modified version of CIGRE B4 HVDC/AC network *.  The results show that the unified algorithm is highly robust against bad data, compared to the traditional methods. 

* CIGRE B4 HVDC/AC network is a network used in research.  CIGRE stands for Conseil International des Grands Réseaux Electriques, where B4 is its HVDC and Power Electronics Study Committee.
 Europe – Energy – Climate: The quest for the clean energy transition in the EU.

Edited by Agnieszka E. Rządkowska. 

This book focuses on recent European energy policies, and features chapters from specialists working in the European energy sector.  InnoDC’s Anubhav Jain contributed the chapter, ‘Technological developments in offshore wind farms’.  If this is your subject area, click on the book title above to order a copy.  

Stability Assessment for Multi-Infeed Grid-Connected VSCs Modeled in the Admittance Matrix From.  IEEE Transactions on Circuits and Systems. 

Authors: Luis Orellana, Luis Sainz, Eduardo Prieto-Araujo, Oriol Gomis-Bellmunt.
The increased use of power electronic converters for renewable-energy integration has been a subject of concern due to the ‘resonance oscillatory phenomena’ caused by poorly damped AC power network interaction.
Lately, studies have focused particularly on AC power networks with high-penetration power converters. Their main aim is to apply traditional stability criteria to small-signal power network dynamic models, which can burden large and complex power systems. 
Luis Orellana’s work addresses this issue by proposing a simple criterion, the PMD (positive-mode damping) stability criterion. It has proved a powerful tool compared to traditional stability criteria, due to its stability-relevant characteristics:
(i) the closed-loop unstable oscillatory modes’ frequency characterisation; 
(ii) detailed information is not required (such as relying on black-box model measurements);
(iii) it is not sensitive to system element associations;
(iv) simple to evaluate and needs less computer effort (short computation time and memory usage); and
(v) visually friendly, delivering physical results.
3rd image above: Luis Orellana on a visit to the Danish wind-farm, Anholt, which is connected to the grid through AC transmission.

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