The most definitive way to get the VWAP for the last 30 minutes will be if you calculate this using tick by tick(TBT) provided by the exchange on a colocation server. More details about TBT data here.
If you see, TBT data comes at a huge infra cost, unless you have a HFT trading platform that requires this, the most cost-effective way to estimate the VWAP for the last 30 minutes is capturing all ticks you receive on Kite Connect APIs(1 or 2 ticks a second, while there could be thousands of trades) and calculating the VWAP which would be a close estimate of the closing price.