Control apparatus and control method for maintaining stable voltage of conflux DC bus in distributed power generation system

Abstract

The invention provides a control apparatus and control method for maintaining stable voltage of a conflux DC bus in a distributed power generation system. In order to enable the current transformers of multiple power generation devices to realize parallel operation under the condition that there is no interconnection line communication, voltage instruction signals are obtained through calculation according to a preset sagging characteristic by actual output currents, current instruction signals are given according to actual conditions by an MPPT algorithm or a system, two control signals obtained through operation of a voltage control loop and a current control loop are sent to the minimum taking link of CPU control software, and the output of the link is used for PWM to ensure no overvoltage in case of a current control mode and ensure no overcurrent in case of a voltage control mode, such that smooth switching of multiple electric power converting devices between the current control mode and the voltage control mode is realized, and under the condition that there are no interconnection communication lines, multiple converters can realize stable parallel output according to power which can be obtained by themselves.

Description

technical field [0001] The invention relates to a DC bus voltage stabilization control technology in a distributed power generation system. Background technique [0002] A distributed power generation system may include multiple photovoltaic solar power generation devices, wind power generation devices, ocean current power generation devices, and biomass power generation devices. Under the conditions of DC bus or DC microgrid, these devices transmit DC power to the busbar. Since the design capacities of these power generating devices are different, even if the capacity is the same, at the same time, due to the influence of weather and environmental factors, there may be large differences in the output power of each generating device. For example, solar power generation has no output at night, while wind power generation is available. [0003] On the other hand, in order to obtain more electric energy from nature, each power generation device may set a maximum power capture...

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Problems solved by technology

[0003] On the other hand, in order to obtain more electric energy from nature, each power generation device may set a maximum power capture (MPPT, Maximum Power Point Tracking) algorithm according to its actual situation, and each device uses a current mode (approximately controllable current source) to The busbar injects energy, so in the independent microgrid mode, it will cause the voltage fluctuation of the DC busbar, which is not conducive to the operation of the whole system

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