Aiming at long- term voltage stabilization scenarios,an emergency voltage controller based on the action-dependent heuristic dynamic programming is designed and is applied to the long- term voltage stabilization of powersystems by coordinating different control schemes.In the investigation,first,an utility function is presented byusing the quadric form of the deviation between bus voltage and its reference value in each control period,and acost- to- go function is constructed by accumulating the utility function in future design.Then,a dynamic program-ming model for long- term voltage stabilization is established.Moreover,two BP neural networks are employed to de-sign the critic network and the action network,respectively,and the Bellman equation is employed to train the cri-tic network which approximates the cost- to- go function and the action network which produces optimal control out-puts,thus obtaining the solution of the dynamic programming model.Finally,a time- domain simulation of NewEngland 10- machine 39- bus system is carried out using PSAT,and the results verify the feasibility and effectivenessof the proposed method.