There’s a bright knock on the door and Unsuk Chin pops her head into the room, punctual to the millisecond. The Berlin-based composer is a compact, glamorous woman in her early 50s, crisply dressed and briskly friendly. “I guess I know my way around here by now!” she says, hanging up her coat with a familiarity that proves her point. Chin is Artistic Director of the Philharmonia’s Music of Today series and I’ve come to meet her backstage at the Southbank Centre in London on the day before her glossy Clarinet Concerto receives its British premiere from Kari Kriikku and the Philharmonia. Later the same week she will fly to the United States, then Korea, then back to Europe — a list she reels off with the efficiency of someone who regularly flits around the globe for brief and important engagements.

This season the BBC Scottish Symphony Orchestra performs three Chin concertos — about which more in a moment — but we beginning by discussing Berlin. She has lived there since the late 1980s but has always tended to keep the musical culture of the place at arms length. I ask whether the city’s evolution in recent decades has impacted the music she writes there, but she shakes her head. “Berlin is a city where I just live,” she says. “It’s a comfortable lifestyle and I can enjoy so much culture, but musically I’m more of a consumer. I’m not very involved in the German contemporary music scene — I’m kind of an outsider. If I go to a concert, I’m usually just one of the audience.”

Why an outsider? Chin is one of the biggest names in contemporary orchestral music and the recipient of numerous top-tier prizes: the 2004 Grawemeyer Award for Music Composition for her Violin Concerto; the 2005 Arnold Schoenberg Prize; the 2010 Prince Pierre Foundation Music Award; the 2012 Ho-Am Prize. Her commissions come from the world’s most prestigious orchestras; her first opera, Alice in Wonderland, was premiered at the Bavarian State Opera; she directs major contemporary music series in Seoul and London — it’s hardly the stuff of an industry outsider.

“Yes, but from the beginning of my life in Germany I didn’t want to be involved in Germany’s particular musical culture,” she explains. “It’s too dogmatic for me, and they have specific expectations of a composer who comes from Asia or a composer who is a woman. I didn’t want to make myself into what they wanted. I wanted to do my own thing.” Later, when we’re discussing her concerto for a Chinese instrument called the sheng, she reveals that she avoided writing any direct melody “because it would sound too much like Asian traditional music. I wanted to write my own music.”

Chin grew up in South Korea in a social context that she describes as “intensely poor”. Her father was a Presbyterian minister and she learned to play piano for church services and weddings. “My musical studies in Korea were very limited,” she says. “I had no information. I came from a country where there was a dictator. Education was limited, and we had little contact with other countries. I wasn’t openminded. I was limited in every part of my life.”

In 1985 she moved to Hamburg to study with the composer Gyorgy Ligeti, who famously derided her portfolio as being unoriginal and forbid her from relying on any stock-modernist tropes borrowed from the European avant-garde. “I had a deep crisis at the beginning,” she says. “I needed time for myself. At that point, I never thought about my career, or how successful I was, or anything like that.”

She didn’t compose for three years until she left Hamburg and moved to Berlin to work at the electronic studio of the Technical University. She remembers being “very curious about all kinds of new things: I liked classical music and romantic music, but I was also open for all kinds of new music. It was an important chance to re-start composition — a very difficult process, but I could do it at the studio. It was a completely new world. I really learned how to think about music.”

Chin’s mature music sounds as though it is always searching for novel sounds and textures — I’m thinking of the sparkling patina of her breakthrough Acrostic Wordplay, or the luscious density of Kalá, or the blithe pyrotechnics of the Violin Concerto. Yet she almost always pursues those new sounds through conventional western instruments and voices rather than integrating the electro-acoustic methods she learned back in 1980s Berlin.

“What interested me wasn’t the electronic music itself,” she says, “but the process of working at the studio with different software and computers. I could research deeply into the inner life of a sound. For me, that was a completely new world.” Later when I re-listen to a recording of Alban Gerhardt playing the burly, propulsive Cello Concerto that Chin wrote for him in 2008, that phrase — the inner life of a sound — keeps coming back to mind.

Nowadays Chin composes only with pen and manuscript paper: no fancy keyboards, no computer software. “Well, of course! I can never imagine working with a computer. I need time to think about something, then I put the note on the page… it’s a very slow process” — she mimes the precision of putting pen to paper with acute concentration. “If I put the note down, I have to feel the energy of it. I can’t describe the feeling. I put down the note, and I know whether it’s going to work or not.”

Is she fussy about her working habits? She shakes her head and laughs. “Actually, I work when I have time. I have a family so there are a lot of other things to do. I organise contemporary music concerts with the Philharmonia and the Seoul Philharmonic, so there is a lot of organisation and correspondence that I need to take care of. I’m always being interrupted by emails so I’ve learned how to make use of 30 minutes here or there. Even when I’m washing dishes in the kitchen I’m thinking about composing.” She smiles. “The best ideas always came while washing dishes!”

Chin’s scores are diligent, detailed and above all accomplished: she is a craftswoman of exquisite skill, regardless of whether her music is dealing in wit (“humour in my music is very important: a kind of black humour, like British humour”) or the unabashed, almost old-fashioned virtuosity of her concertos. In a piece like the Clarinet Concerto — full of multiphonics and flash arabesques — she revels in virtuosity for the sake of, well, virtuosity.

She says that she loves to push the technical reaches of a soloist, and to explore the relationship between soloist and the orchestra from several angles. “My ideas spring from the virtuosity of each musician. These musician have played one instrument for their whole life — it’s amazing! So I want them to stand on stage and push themselves further in their mental and musical possibilities. All of my concertos are technically really difficult. Everybody has to fight to survive.” And she constantly makes herself brave the same gauntlet, too. “During the compositional process I always try to go beyond my limit. It’s a difficult process, but it’s fascinating. If you only did what you already know you can do… Well, that would be so boring.”

The BBC Scottish Symphony Orchestra performs Unsuk Chin’s Su (Concerto for Sheng) with Wu Wei at City Halls tomorrow. Kari Kriikku plays the Clarinet Concerto on 14 January and Vivian Hagner plays the Violin Concerto on 7 April 2016.