Wind power is growing rapidly around the world as a means of dealing with the
world energy shortage and associated environmental problems. Ambitious plans
concerning renewable energy applications around European countries require a
reliable yet economic system to generate, collect and transmit electrical power from
renewable resources. In populous Europe, collective offshore large-scale wind farms
are efficient and have the potential to reach this sustainable goal. This means that an
even more reliable collection and transmission system is sought. However, this
relatively new area of offshore wind power generation lacks systematic fault
transient analysis and operational experience to enhance further development. At the
same time, appropriate fault protection schemes are required.
This thesis focuses on the analysis of fault conditions and investigates effective fault 5 S; G# i; k6 v, L9 kride-through and protection schemes in the electrical systems of wind farms, for both . F* Z- t: w4 w! e% msmall-scale land and large-scale offshore systems. Two variable-speed generation& L+ i. l5 n" @8 w* P/ a
systems are considered: doubly-fed induction generators (DFIGs) and permanent , c6 S0 J+ g* N* l0 j8 lmagnet synchronous generators (PMSGs) because of their popularity nowadays for* Z* M/ y) N3 l2 a& |3 l+ b+ }
wind turbines scaling to several-MW systems. The main content of the thesis is as 8 ?" O9 H( i4 mfollows. The protection issues of DFIGs are discussed, with a novel protection0 T" ~8 V* e2 x3 S3 d
scheme proposed. Then the analysis of protection scheme options for the fully rated , U& D U _4 g/ T! o8 F- Mconverter, direct-driven PMSGs are examined and performed with simulation6 ^, A- v: U `7 P
comparisons. Further, the protection schemes for wind farm collection and 6 H; l( E( f' r5 j* dtransmission systems are studied in terms of voltage level, collection level − wind% S1 \& R; Z- u6 D2 F1 k9 W* ]
farm collection grids and high-voltage transmission systems for multi-terminal DC! g9 }! [3 z) `& A( b& v
connected transmission systems, the so-called “Supergrid”. Throughout the thesis,3 Q3 |6 y3 a8 u7 B
theoretical analyses of fault transient performances are detailed with& Q& R5 U* B- X% G1 B& ~, _ pscad/EMTDC simulation results for verification. Finally, the economic aspect for . X7 s: }) h0 S D% X$ X+ Y# |possible redundant design of wind farm electrical systems is investigated based o
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