This paper presents an active voltage restorer in power grids. The regulator is made up of several transformers and matrix converters. It can output as many as thirteen kinds of voltages, which can be used to compensate the power grid voltage. The restorer can be used to regulate the grid voltage actively. This paper analyzed the equivalent circuits of the restorer and the switching methods of the switches in the system is proposed. The restorer has many merits such as wide operation range, high performance and low cost. Not like the traditional voltage restorers, the proposed topology not only can increase the output voltage, but also can decrease the output voltage. Hence the power grid voltage can be maintained in the desired range. The simulation results validated the proposed topology and the control scheme.