Power grid simulator topological structure and control method thereof

Abstract

The invention discloses a power grid simulator topological structure and a control method thereof. The topological structure comprises an A phase, a B phase, a C phase, an A phase LC filter, a B phase LC filter and a C phase LC filter, an A phase transformer, a B phase transformer and a C phase transformer and a load, wherein the A phase, the B phase and the C phase are identical in structure. A simulator can operate in a four-quadrant mode, feedback of electric energy to a power grid is achieved, three-phase power grid voltage output can be provided, and various power grid fault conditions such as voltage drop, frequency deviation, three-phase imbalance and harmonic distortion of the power grid can be simulated. On the level of designing the controller, the control mode of the power grid simulator is divided into fundamental wave control and harmonic wave control, namely, a low-frequency large-capacity module and a high-frequency small-capacity module are controlled respectively. In addition, a direct current side voltage follow-up control strategy is provided to solve the problem of power mismatching among modules.

Description

technical field [0001] The invention belongs to the field of power electronic converters and their control, and in particular relates to a network simulator topology and a control method thereof. Background technique [0002] In order to connect distributed power generation systems such as photovoltaics and wind power to the grid, it is necessary to perform a grid adaptability test before grid integration. However, since the grid is a huge system, it is difficult to perform a grid adaptability test. And the main function of the power grid is to provide users with standard three-phase sinusoidal voltage, and various forms of power grid faults are not common. Specialized equipment is therefore required to simulate grid faults and test distributed generation systems. The function of the power grid simulator is to simulate various faults in the output power grid. It can not only output normal grid voltage, but also simulate common faults such as voltage drop, three-phase unbala...

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Problems solved by technology

[0003] The existing topological structure of the power grid simulator mostly adopts uncontrollable rectification at the front stage and three-phase PWM inverter structure at the rear stage, but it cannot realize four-quadrant operation, and it is only suitable for medium and low-voltage small-capacity systems, and is not suitable for large-capacity systems

At present, the control strategies of the grid simulator mainly include proportional integral control, repetitive control, sliding mode variable control, etc., but the proportional integral controller can only track the amplitude of the grid without difference, and there is a static difference value for the tracking of the given voltage. , time delay and oscillation; repetitive control has good steady-state output characteristics and robustness, but there is a problem of output delay of one fundamental cycle and poor dynamic performance; sliding mode variable structure is nonlinear control, open and close Control characteristics, resulting in chattering phenomenon, etc.

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