The invention provides a system for controlling power grid failure for a reactive power compensation device. The system includes a primary circuit module of the reactive power compensation device and a control module which is intended for controlling the reactive power compensation device. The operation model of the primary circuit module is an ideal current power model. The control module includes a signal acquisition unit, a normal control policy unit, a failure control policy unit, a failure identifying unit and an output unit. According to the invention, the system fully takes into consideration of modeling, failure identifying modeling and failure ride-through modeling and the like in the scenario when the reactive power compensation apparatus works normally. The system can perform setting through the user interface of a model, further achieves accurate modeling of reactive power compensation devices of various kinds in wind farm, and at the same time increases the flexibility, accuracy and reliability in modeling.