Fast non-recursive extraction of individual harmonics using artificial neural networks

A collaborative work between Northumbria University and University of Peradeniya (Sri Lanka). It presents a novel technique based on Artificial Neural Networks for fast extraction of individual harmonic components. The technique was tested on a real-time hardware platform and results obtained showed that it is significantly faster and less computationally complex than other techniques. The paper complements other publications by the author (see paper 1) on the important area of “Power Quality” of electric power networks. It involves the application of advanced techniques in artificial intelligence to solve power systems problems

Measuring the energy handling capability of metal oxide varistors

Metal oxide varistors are widely used in many power electronics circuits to protect against transient over voltages. Certain applications are very demanding on the energy handling capability of the varistors. This paper gives an overview of the failure modes of ZnO varistors and investigates their characteristics when subjected to repetitive current pulses. It describes the puncture failure mode caused by melting of a region in the varistor of local current concentration. Experimental tests are performed to evaluate the puncture energy using an infrared imaging camera. A relationship between the energy absorption and the varistor maximum surface temperature is obtained. It is shown that the destructive energy depends strongly on the uniformity of the varistor; the more uniform, the higher the energy handling capability. The paper also presents the results of nondestructive tests using a scanning acoustic microscope to evaluate the uniformity of the varistor

Evaluation of the effects of rotor harmonics in a doubly-fed induction generator with harmonic induced speed ripple

This paper is concerned with the low-frequency harmonics which originate from the rotor inverter of a doubly-fed induction generator (DFIG). By including the mechanical speed response, it expands the transformer approach previously taken to analyze the harmonic transfer in the machine. A numerical method is proposed to calculate the stator current sidebands, which can be used to predict the voltage fluctuation at the system busbar. It is shown that the pulsating torque associated with the rotor harmonics can induce speed ripple depending on the inertia, causing a significant change in the stator current spectrum. Experiment and simulation verify the analysis and the proposed calculation method

ACN-Data: Analysis and Applications of an Open EV Charging Dataset

We are releasing ACN-Data, a dynamic dataset of workplace EV charging which currently includes over 30,000 sessions with more added daily. In this paper we describe the dataset, as well as some interesting user behavior it exhibits. To demonstrate the usefulness of the dataset, we present three examples, learning and predicting user behavior using Gaussian mixture models, optimally sizing on-site solar generation for adaptive electric vehicle charging, and using workplace charging to smooth the net demand Duck Curve

Smart EV charging schedules: supporting the grid and protecting battery life

Uncontrolled charging of electric vehicles (EVs) is expected to cause problems for power distribution networks as existing vehicles are continually being replaced by electric. Therefore, smart charging algorithms that prevent such problems will become necessary as uptake of EVs increases and they become more popular. Smart EV charging is not only useful to provide the necessary charge (energy) required by the user but may also be used to support the grid and protect battery health, which is investigated in this study. Factors that affect battery life are quantified and their impact on battery degradation and ability (of EV) to support the grid are analysed. Charging regimes that can meet the driver needs, provide grid support and protect the state of health of the battery are proposed in this study. The analysis presented demonstrates that smart charging that involves charging before departure, less frequent charging and limited vehicle-to-grid can prolong battery life compared with providing the same EV charge in an uncontrolled way. Thus, grid power is supported and battery life is protected by the proposed smart charging regimes

The developing landscape of electric vehicles and smart grids: a smart future?

This paper attempts to connect debates on decarbonisation at international and European scale with discussions on smart grid developments,in the interaction of the international automotive industry,and government policy. Thus,the paper reviews policy frameworks and business strategies