When did Nikola Tesla invented niagara falls powerplant?

Nikola Tesla designed the first hydro-electric power plant in Niagara falls. This was the final victory of Tesla's Alternating Current over Edison's Direct Current. The evolution of electric power from the discovery of Faraday in 1831 to the initial great installation of the Tesla polyphase system in 1896 is undoubtedly the most tremendous event in all engineering history.