* Ardian Private Equity Fund sells 25.48 pct in Encevo utility. : PARIS (Reuters) - State-owned China Southern Power Grid has agreed to buy a minority stake in European utility Encevo, as Chinese firms continue to acquire assets in Europe even as governments in the region try to limit their influence. Private equity firm Ardian said on Tuesday it had agreed to sell its 25.48 percent stake in Encevo to China Southern Power Grid. Encevo has two main subsidiaries - Creos and Enovos Luxembourg.