Power ramp rate reduction in photovoltaic power plants using energy storage
Author
Nikolov, Dimitar Nikolov
Term
4. term
Education
Publication year
2017
Submitted on
2017-06-01
Pages
44
Abstract
This thesis examines how energy storage can be used to reduce fast power changes (ramp rates) in photovoltaic (PV) plants to support grid stability and comply with limits such as 10%/min. The research question is addressed by comparing PV power smoothing strategies: first- and second-order low-pass filters, moving average, exponential moving average, and a gradient-based ramp-rate controller. A PV generator and a Li-ion battery are modeled, and the methods are evaluated in simulation using different irradiance profiles to assess strengths and weaknesses with respect to ramp-rate compliance, smoothing performance, battery sizing, and utilization. Two promising methods are then implemented experimentally to assess practical effectiveness. The thesis discusses trade-offs in filter tuning (e.g., delay and potentially unnecessary battery use on clear-sky days) and notes that the gradient method avoids reliance on past values. It also estimates the minimum battery size required to meet ramp-rate requirements. Although limited to three days of irradiance data, idealized converters, and neglect of maximum power point search time, the work provides guidance for selecting and implementing simple, robust, and practical smoothing strategies in PV plants with batteries.
Denne afhandling undersøger, hvordan energilagring kan bruges til at reducere hurtige effektændringer (ramp rates) i fotovoltaiske (PV) anlæg for at støtte netstabilitet og overholde grænser som 10 %/min. Arbejdet afklarer forskningsspørgsmålet gennem en sammenligning af metoder til at udjævne PV-effekt: første- og andenordens lavpasfiltre, bevægende gennemsnit, eksponentielt bevægende gennemsnit og en gradientbaseret ramp-rate-kontrol. En PV-generator og en Li‑ion batterienhed modelleres, og metoderne evalueres i simulering med forskellige irradiansprofiler for at vurdere styrker og svagheder med fokus på ramp-rate-overholdelse, udjævningsgrad, batteridimensionering og -udnyttelse. To lovende metoder implementeres derefter eksperimentelt for at vurdere praktisk effektivitet. Afhandlingen diskuterer bl.a. afvejninger ved filtertuning (f.eks. forsinkelse og potentiel unødvendig batteribrug på klare dage) og at gradientmetoden ikke afhænger af historiske værdier. Desuden estimeres minimum batteristørrelse for at opfylde givne ramp-rate-krav. Arbejdet er begrænset af brugen af tre dages irradiansdata, idealiserede konvertere og udeladelse af søgetid for maksimal power point, men giver retningslinjer for valg og implementering af simple, robuste og praktiske udjævningsstrategier i PV-anlæg med batteri.
[This apstract has been generated with the help of AI directly from the project full text]
Keywords