The large-scale connection of renewable energy sources (RES) to the grid has led to an increasing energy storage demand in power system. The high price of the energy storage system greatly raises the construction cost. Electric spring (ES) is an emerging technology for demand-side management. The first version ES (ES-1) is originally intended to reduce the energy storage demand, but it can only compensate reactive power. The second version ES (ES-2) has rich functions, but it needs energy storage battery. Compared with ES-1, ES-2 adds additional energy storage unit in power system. This paper investigates the ability of ES-2 to reduce energy storage demand and proposes a load voltage angle control strategy that can adjust the phase angle difference between critical load (CL) voltage and non-critical load (NCL) voltage in real time. By adjusting the phase angle difference, the active power of ES can be controlled so that the NCL allowable power fluctuation range can be fully utilized to reduce the energy storage demand in power system. The effectiveness of the proposed scheme has been verified in real time simulator RT-BOX.