Offshore Wind Power System Optimal Operation with Efficiency and Reliability Improvement
Authors
Majumder, Mahmudul Alam ; Mozumder, Md Abdul Kuddus Remon
Term
4. term
Education
Publication year
2026
Submitted on
2026-10-23
Abstract
This project explores how offshore wind power systems can be operated to achieve both high efficiency and improved reliability. The study focuses on the generator side of a Type-4 wind turbine with a direct-drive Permanent Magnet Synchronous Generator (PMSG), connected to a DC load via a three-phase diode rectifier and a DC–DC boost converter. Because offshore maintenance is costly and challenging, it is crucial to limit thermal stress in the converter’s IGBT switches, whose wear-out is driven by repeated heating and cooling cycles. Three detailed models are developed: an efficiency and power-loss model that separates conduction and switching losses; an electro-thermal model that computes the device junction temperature from these losses; and a reliability model that estimates lifetime and accumulated damage using the Coffin–Manson and Bayerer lifetime models combined through Miner’s rule. Based on these models, a temperature-triggered supervisory control strategy is designed in which two Perturb and Observe (P&O) MPPT controllers operate in parallel: a conventional controller that aims at maximum power extraction and a soft controller that limits the IGBT current and input power. When the estimated junction temperature reaches a threshold of 125 °C, the system switches to the soft MPPT, allowing the turbine to capture maximum power under low thermal stress and only reducing stress when the device becomes too hot. The approach does not require wind-speed measurements, as the decision is based solely on the estimated junction temperature. Simulation studies in MATLAB/Simulink at steady wind speeds of 10 and 12 m/s and for a wind step from 10 to 12 m/s show that conduction losses dominate and that the calculated efficiency matches the Simulink results. At moderate wind speed, the device remains cool and experiences low stress, whereas at higher wind speed with conventional MPPT the device losses and junction temperature increase significantly, exceeding the threshold and clearly reducing the expected lifetime. Under dynamic wind conditions, the soft MPPT is activated when the threshold is reached, reducing current and junction temperature, lowering accumulated damage in both lifetime models, and extending the expected lifetime without compromising converter efficiency. The results demonstrate that switching between conventional and soft MPPT based on junction temperature can balance efficiency and lifetime in offshore wind converters, and suggest reliability-aware control as a promising strategy; future work includes laboratory validation and studying optimal switching back to conventional MPPT.
Dette projekt undersøger, hvordan offshore vindkraftsystemer kan drives mere effektivt og samtidig få længere levetid. Fokus er på generator-siden af en type-4 vindmølle med en direkte-drevet permanentmagnet-synkrongenerator (PMSG), som er koblet til en DC-belastning via en trefaset diodensretter og en DC-DC boost-konverter. Da vedligeholdelse til havs er dyr og vanskelig, er det afgørende at reducere den termiske belastning i konverterens IGBT-switche, som over tid nedbrydes af gentagne opvarmnings- og afkølingscyklusser. Der udvikles tre detaljerede modeller: en effektivitets- og tabmodel, som opdeler konvertertabet i lednings- og koblingstab; en elektro-termisk model, som beregner junction-temperaturen ud fra tabene; og en reliabilitetsmodel, som estimerer levetiden og akkumuleret skade ved hjælp af Coffin–Manson- og Bayerer-modeller kombineret med Miners regel. Oven på disse modeller designes en temperaturbaseret overordnet styring, hvor to Perturb and Observe (P&O) MPPT-regulatorer arbejder parallelt: en konventionel regulator, der maksimerer effektoptaget, og en “soft” regulator, der begrænser IGBT-strømmen og indgangseffekten. Når den beregnede junction-temperatur når en tærskel på 125 °C, skifter styringen automatisk til den soft MPPT, så vindmøllen kan høste maksimal effekt ved lave termiske belastninger og kun reducerer belastningen, når komponenten bliver for varm. Simuleringer i MATLAB/Simulink ved statiske vindhastigheder på 10 og 12 m/s samt med et vindstød fra 10 til 12 m/s viser, at ledningstabene dominerer, og at den beregnede effektivitet stemmer godt overens med Simulink-resultaterne. Ved moderat vindhastighed forbliver IGBT’en kølig og under lav termisk stress, mens høj vindhastighed med konventionel MPPT medfører markant højere tab, øget junction-temperatur over tærsklen og reduceret forventet levetid. I den dynamiske case aktiveres den soft MPPT, når tærsklen overskrides, hvilket sænker strøm og junction-temperatur, mindsker akkumuleret skade i begge levetidsmodeller og forlænger levetiden uden at reducere konverterens effektivitet. Resultaterne indikerer, at temperaturtriggeret skift mellem konventionel og soft MPPT kan balancere effektivitet og reliabilitet i offshore vindkonvertere og dermed bidrage til længere levetid; fremtidigt arbejde omfatter laboratorietests og undersøgelser af, hvordan systemet optimalt kan skifte tilbage til konventionel MPPT.
[This abstract has been generated with the help of AI directly from the project full text]