Direct control method and system for internal potential of bridge arm of new energy grid-tied inverter

#The present disclosure is in the technical field of grid-tied inverter (GTI) control, and in particular relates to a direct control method and system for an internal potential of a bridge arm of a new energy GTI.

#The grid-following GTI features fast power regulation speed and high utilization rate of renewable energy. However, generally with the maximum active power output as the main operation target, the grid-following GTI fails to support the power grid voltage and frequency stability as the traditional synchronous generator does. As the permeability of the new energy power generation develops increasingly, the power grid has gradually changed from strong power grid to weak power grid. To enhance the adaptability of GTI under complex operating conditions, the grid-forming inverter has come into being.

#The grid-forming inverter has the potential to simulate the damping and inertia of the traditional synchronous generator, and can provide frequency and voltage support for the power grid. However, the grid-forming inverter face the risk of oscillation in the case of strong grid, which leads to the instability of grid-tied system.

#To explain the examples of the present disclosure or the technical solutions in the prior art more clearly, a brief description will be given below with reference to the accompanying drawings which are used in the description of the examples or the prior art. Obviously, other drawings can be obtained according to these drawings without creative efforts for those ordinary skilled in the art.

#FIG. 1 is a schematic diagram of a circuit topology and a control method of a three-phase GTI according to the present disclosure;

#FIG. 2 is a schematic diagram of a state observer model according to the present disclosure;

#Technical solutions in the examples of the present disclosure will be described clearly and completely in the following with reference to the accompanying drawings in the examples of the present disclosure. Obviously, the described examples are only some, rather than all examples of the present disclosure. On the basis of the examples in the present disclosure, all other examples obtained by those ordinary skilled in the art without creative efforts belong to the protection scope of the present disclosure.

#As shown in FIG. 1, a direct control method for an internal potential of a bridge arm of a new energy GTI is provided. Topological structures of the GTI to which the control method is applied include a DC-side power supply, a three-phase inverter, a three-phase power grid impedance and a three-phase power grid. The three-phase inverter includes a three-phase inverter circuit, a three-phase LC filter, a three-phase voltage sensor, a three-phase current sensor and a three-phase inverter controller.

#In the three-phase inverter, the three-phase inverter circuit is connected to the three-phase LC filter, the three-phase voltage sensor and the three-phase current sensor respectively sample a three-phase voltage of a filtering capacitor and a three-phase current of a filtering inductor of the three-phase LC filter, and transmit sample signals to the three-phase inverter controller; and the three-phase inverter controller outputs drive signals to control the three-phase inverter circuit after calculation.