Flexibility and regulation capability of hydropower systems to balance large amounts of wind power : Influence of plant properties and hydrological conditions

The vast expansion of wind power in Sweden has raised questions about the regulation capability of existing hydropower resources. In this paper, the flexibility and relative regulation contribution of two large regulated rivers subject to increasing wind power penetration and different hydrological conditions is analysed through model-based simulations. A 28-day scenario is simulated using detailed models of the two hydropower systems, normally used at Vattenfall for day-ahead production planning. Numeric measures are introduced to measure flexibility and regulation contribution and two properties that characterise a good regulation plant are identified. It is found that the flexibility of a plant is correlated to the discharge factor and that the relative regulation contribution is nearly proportional to the available regulating power. Further it is found that large inflow of water reduces the flexibility in plants or reaches with a small discharge factor

Flexibility and regulation capability of hydropower systems to balance large amounts of wind power : Influence of plant properties and hydrological conditions

The vast expansion of wind power in Sweden has raised questions about the regulation capability of existing hydropower resources. In this paper, the flexibility and relative regulation contribution of two large regulated rivers subject to increasing wind power penetration and different hydrological conditions is analysed through model-based simulations. A 28-day scenario is simulated using detailed models of the two hydropower systems, normally used at Vattenfall for day-ahead production planning. Numeric measures are introduced to measure flexibility and regulation contribution and two properties that characterise a good regulation plant are identified. It is found that the flexibility of a plant is correlated to the discharge factor and that the relative regulation contribution is nearly proportional to the available regulating power. Further it is found that large inflow of water reduces the flexibility in plants or reaches with a small discharge factor

Flexibility and regulation capability of hydropower systems to balance large amounts of wind power : Influence of plant properties and hydrological conditions

The vast expansion of wind power in Sweden has raised questions about the regulation capability of existing hydropower resources. In this paper, the flexibility and relative regulation contribution of two large regulated rivers subject to increasing wind power penetration and different hydrological conditions is analysed through model-based simulations. A 28-day scenario is simulated using detailed models of the two hydropower systems, normally used at Vattenfall for day-ahead production planning. Numeric measures are introduced to measure flexibility and regulation contribution and two properties that characterise a good regulation plant are identified. It is found that the flexibility of a plant is correlated to the discharge factor and that the relative regulation contribution is nearly proportional to the available regulating power. Further it is found that large inflow of water reduces the flexibility in plants or reaches with a small discharge factor

Verksamhetsutveckling med hjälp av standardisering i ett SMF : En fallstudie där Gnosjöandan möter standardiserade arbetssätt

Fallföretaget är i behov av standardiserade rutiner fördokumentation. Även införande av arbetsinstruktioner är nödvändigt för att reducera risken av att vara beroende av enskilda individers kunskap. Detta blir i synnerhet kritiskt vid en eventuell generationsväxling. En av fallföretagets mest kritiska punkt beror på underleverantörer och dess ojämna kvalitet samt oregelbunden leveranssäkerhet. Därmed ser vi ett tydligt behov av leverantörspolicies. Vi ser även att dagens kommunikationsflöde inte är hållbar vid ytterligare expansion.Tydliga ansvarsområden bör utformas i linje med fallföretagets värderingar som också bör formuleras. För att få ett effektivare kommunikationsflöde bör fallföretaget se över möjligheterna att implementera ett nytt affärssystem. Ovanstående medför förbättrad materialhantering samt insamlingen av data som kan bearbetas vilket slutligen effektiviserar processerna i verksamheten inom ramen för standardisering. I samband med att medarbetare utbildas inom ständiga förbättringar skapas en mer självstyrd grupp med ett standardiserat förbättringstänk. Slutligen bedömer vi att Gnosjöandan tillsammans med leankonceptet med fokus på 5S skall införas och kombineras där Gnosjöandan kan beaktas som ett komplement till 5S i vårt fallföretag. Detta är för få en förbättrad struktur och en jämn standardiserad kvalitet kring rutiner och processer vilket skulle frambringa en utmärkande styrka i fallföretag. Vidare bedömer vi att svenskt näringsliv, framförallt SMF kan dra nytta av Gnosjöandans tänk som ett komplement till leankonceptet

A New Approach to Obtain Synthetic Wind Power Forecasts for Integration Studies

When performing wind integration studies, synthetic wind power forecasts are key elements. Historically, data from operational forecasting systems have been used sparsely, likely due to the high costs involved. Purely statistical methods for simulating wind power forecasts are more common,but have problems mimicking all relevant aspects of actual forecasts. Consequently, a new approach to obtain wind power forecasts for integration studies is proposed, relying on long time series of freely and globally available reforecasts. In order to produce synthetic forecasts with similar properties as operational ditto, some processing (noise addition and error reduction) is necessary. Validations with measurements from Belgium and Sweden show that the method is adequate; and distributions, correlations, autocorrelations and power spectral densities of forecast errors correspond well. Furthermore, abrupt changes when forecasts are updated and the existence of level and phase errors are reproduced. The influence from terrain complexity on error magnitude is promising, but more data is necessary for a proper validation

Influence of Soot Particle Aggregation on Time-Resolved Laser-Induced Incandescence Signals

Laser-induced incandescence (LII) is a versatile technique for quantitative soot measurements in flames and exhausts. When used for particle sizing, the time-resolved signals are analysed as these will show a decay rate dependent on the soot particle size. Such an analysis has traditionally been based on the assumption of isolated primary particles. However, soot particles in flames and exhausts are usually aggregated, which implies loss of surface area, less heat conduction and hence errors in estimated particle sizes. In this work we present an experimental investigation aiming to quantify this effect. A soot generator, based on a propane diffusion flame, was used to produce a stable soot stream and the soot was characterised by transmission electron microscopy (TEM), a scanning mobility particle sizer (SMPS) and an aerosol particle mass analyzer coupled in series after a differential mobility analyzer (DMA-APM). Despite nearly identical primary particle size distributions for three selected operating conditions, LII measurements resulted in signal decays with significant differences in decay rate. However, the three cases were found to have quite different levels of aggregation as shown both in TEM images and mobility size distributions, and the results agree qualitatively with the expected effect of diminished heat conduction from aggregated particles resulting in longer LII signal decays. In an attempt to explain the differences quantitatively, the LII signal dependence on aggregation was modelled using a heat and mass transfer model for LII given the primary particle and aggregate size distribution data as input. Quantitative agreement was not reached and reasons for this discrepancy are discussed