August 4th

Damped-Type Double Tuned Filters Design for HVDC Systems

The ac/dc filters are always needed in HVDC converter stations to suppress harmonic currents/voltages. The ac side filters are also employed to compensate network requested reactive power. Among different types of filters, double tuned passive filters have been widely utilized in HVDC stations, yet these filters are still not considered well developed. This paper presents an algorithm for design of the conventional and damped-type double tuned filters to reduce harmonic distortion and improve power factor in electrical systems.

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Search for Network Parameters Preventing Ferroresonance Occurrence

Application of the continuation and bifurcation method for studying the influence of network parameter values (e.g. source voltage, network capacitance or damping resistance loading the broken delta of voltage transformers (VT) tertiary windings) on network stability is described in the article. It is possible to estimate in this way sensitivity of the network to ferroresonance occurrence after a fault such as breaker switching or ground short-circuit. The advantages and limitations of the method are given.

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An experimental evaulation of short-time flicker index

A waveform generator capable of supplying an interharmonically distorted voltage supply was constructed and used to evaluate the human perception of light flicker. The light flicker index (Pst), as defined in IEC guidelines [1] is a measure of perceived light flicker. Comparisons were made of light flicker experienced to corresponding values of Pst measured. Results show that the Pst value of 1 is a good indicator of unacceptable flicker.

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July 31st

Connecting Distributed Generation (DG) units to the network

By David Chapman & Bruno De Wachter

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July 30th

New report on Opportunities and Challenges for the concentrating photovoltaic power industry

Thanks to Belen Galego from CSPToday for pointing us to this new NREL report about the opportunities and challenges for development of a mature concentrating photovoltaic power industry. It's about 20 pages packed with interesting information.

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July 17th

Wind energy subsidies yield more than they cost

Wind energy is often criticised by competing forms of energy generation for some of its perceived aspects. It is said to cause dispatching problems, to be more expensive than fossil fuel, to have a limited global potential, and to represent a high cost to society. This last critique has now been contradicted by GE Energy Financial Services.

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July 11th

Toroidal cores

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July 10th

10% solar electricity in the US by 2025

A new study by Clean Edge concludes that generating 10% of the electricity consumed in the US with solar energy by 2025 is a feasible target. The Utility Solar Assessment (USA) Study has presented utilities, solar companies, and regulators a roadmap of how to reach this target.

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July 3rd

New growth factors for wind industry

The wind sector has been growing spectacularly over the past decade. However, to sustain these impressive growth figures over the next twenty years in Europe and North America, business-as-usual will not be enough. In several European countries, the number of remaining onshore sites for building new wind farms is already declining (see interview with François and Benoît Henriet, 'Barriers for wind projects', on this blog).

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July 1st

Are we running out of energy efficiency?

Improving energy efficiency has been a constant concern ever since the oil crisis of the seventies. Today, it is seen as one of the solutions for mitigating climate change and improving energy security. Many numbers for energy saving potentials circulate, but how realistic are these? Despite the current high oil price, energy efficiency improvements these days are not as big as they were during the first oil crisis. Why is energy efficiency so hard to pursue? Have we really exhausted the energy savings potential?

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