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    Ampere's law to calculate the B field from a balanced three-phase system

    I am a little confused when I try to use Ampere's law to calculate the B field from a balanced three-phase system. Consider the following, shown in the picture below: Lets say I want to calculate the value of B at a distance r (radius of my Amperian loop), the value of r is big enough so that...
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    Suggestions for a Power System Analysis book?

    Hi, I want a book about power system analysis that I can have laying around and read from time to time. I have taken a course in power system analysis some time ago, where I was taught simple fault analysis including unbalanced faults, frequency and voltage control. So to maintain this...
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    Phase Locked Loop

    I have some trouble fully understanding the PLL block diagram shown below in the figure. The PLL circuit is used to generate currents (i alpha and i beta) which are in phase with the positive fundamental sequence of the voltage. I am using the book "Instantaneous Power Theory and Applications...
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    Positive Sequence Detector

    Hi, I am studying a positive sequence detector and have some trouble understanding it. I understand most of it, but the author in the book "Instantaneous Power Theory and Applications to Power Conditioning" writes: For extracting the fundamental positive-sequence voltage with the dual method...
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    Harmonic sources, flowing from load, why?

    I have been thinking of this and can not seem to understand why nonlinear loads can be tought of harmonic current sources injecting current back into the grid? For example if you connect a passive filter in parallel to attenuate the 5th harmonic, the 5th harmonic would flow between the filter...
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    Boost converter in Simulink problem

    Hi I am trying to simulate a boost converter in Simulink, but I have a problem. When I measure the inductor current it shows as a triangular waveform instead of an exponential waveform like I would expect, does anyone know why? Does simulink do some simplification I am not aware of...
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    Help me understand transformer vector groups

    Hi, I have problems understanding why, for example, a Yd1 connection introduces a -30 degree phase shift, see image below. How should I think when I want to produce vector groups like that, and derive myself what the phase shift should be? Thanks..
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    Virtual Intertia in Power Systems

    Hi again PF. I recently came across the term "virtual inertia" when reading about photovoltaics and power converters (DC/DC, DC/AC etc.). Article:, not sure if people are able to view the article, I have access via university library...
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    Odd Harmonics in Power System - reduction

    Hi, could anyone explain to me how odd harmonics in the power system are reduced or removed? I've read that in transformers the harmonics produced by the load circulate if the secondary side is wired as delta configuration, yet star is usually used on secondary side i believe? I've looked...
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    Engineering Power Quality with focus on harmonics

    Hi Anyone got any suggestions/recommendations for literature either available for free online or books that I have to buy? My background: Electrical engineering student, working on a project that is about analysis of power quality with focus on harmonics.
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    Pelton Turbine - Cavitation

    Hi, I have a question; can cavitation occur in Pelton turbines? From my understanding we have atmospheric pressure inside the turbine at the runner wheel, so that means cavitation will not occur? However I read somewhere that there was some problems with cavitation in a Pelton turbine, so that...
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    Salient and Non-Salient pole Synchronous Generator

    Hi, I was wondering if some kind soul could explain to me why salient pole machines are preffered in hydropower? From what I've read salient pole machines are preffered for applications with "low" rpm, while non-salient poles are used for applications that runs at higher rpm. O What is the...
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    Voltage and Reactive Power Relationship

    Hi, I have some trouble regarding the relationship between voltage and reactive power. From what I've read you control the amount of reactive power the generator is producing or absorbing by increasing or lowering the excitation of the generator. I have some trouble getting my head around...