The Carlin Motorsport driver, starting from pole, resisted the temptation to pit early in case the safety car came out, putting in some fast laps instead, which helped assure him of victory. Under the series rules cars cannot pit under the safety car, which was used extensively at the new street circuit.
"This is another good result - one step up from the last race this morning," said the Australian. "We've been quick all year and now the finishes are starting to come. We're catching [series leader Robert] Kubica in the points."
Alx Danielsson (Dams) was another driver who opted to pit later on lap eight, two after Power, on his way to second. The Swede has been fighting for fitness since breaking his ankle in a crash in round one at Zolder and was delighted with the result.
Front-row starter Milos Pavlovic (GD Racing) dropped to eighth place after pitting at the end of lap two, but he came through to make the final podium position just ahead of Colin Fleming (Jenzer Motorsport).
Race one winner Kubica, the first to become a double winner this season, had to be content with eighth, after starting from the third row.
Raffaele Giammaria (Dams) was a non-starter after crashing in race one, allowing non-qualifier Andreas Zuber (Carlin) into race two. As in race one, Zuber again used the opportunity to set the race's fastest lap, finishing 16th from the back.
Enrico Toccacelo (Victory Engineering) and Celso Miguez (Pons Racing), who both led at one point, faced disappointing outcomes. Toccacelo was 20th after a clash with 19th-placed Tristan Gommendy (KTR), and Miguez retired with broken steering after a coming together with fifth-placed Eric Salignon (Cram Competition).
Cadillac’s lead designer Chris Mikalauskas worked with Cadillac Racing and Dallara on the styling of the V-LMDh to impart the brand’s identity on a full-house racing car. Here he explains how that came to be
The 2015 Formula Renault 3.5 season will be notable for being the last with the French company's backing but also produced a worthy champion in Oliver Rowland. PETER MILLS evaluates this year's crop of drivers
Last year's field was extraordinary and hard to match, but the Formula Renault 3.5 grid will still have plenty of talent this season. Glenn Freeman runs through the field ahead of this weekend's season opener
Landing the Fortec seat that took rising star Robin Frijns to the 2012 FR3.5 title was already a good sign for Stoffel Vandoorne. Then McLaren took him under its wing. Peter Mills tells Vandoorne's story so far