Coordinated control method for additional damping of optical storage power generation system

Abstract

The invention discloses a control method for improving system damping characteristics of a photovoltaic energy storage power generation system in a multi-power coordinated manner. When a power grid operates normally, the energy storage system can stabilize fluctuations of photovoltaic output power, a photovoltaic grid-connected inverter keeps voltage of a DC bus to be stable, and achieves grid-connected current control. When the power grid fails, the power of the system oscillates since the photovoltaic system has no damping effect on a power system, the drop and recovery of voltage of the power grid can cause drastic fluctuations in the voltage of the DC bus, thereby affecting stable operation of the power grid. The coordinated control method provided by the invention regards DC bus voltage variation as a judging condition, achieves the switching of control modes of the photovoltaic grid-connected inverter and a storage battery during the system oscillating process. The control method can suppress power oscillation of the system, brings convenience for the photovoltaic energy storage power generation system to achieve fault ride-through, and improves system operation stability.

Description

technical field [0001] The invention relates to a control method for coordinating and improving the damping characteristics of the system with multi-power sources of an optical-storage combined power generation system. Background technique [0002] The low-frequency oscillation of the power system has an important impact on the safe and stable operation of the system, and for regional power grids with a high proportion of photovoltaic power generation installed capacity, this problem will become more prominent. In modern power systems, damping low-frequency oscillations is mainly achieved by assembling a power system stabilizer (powersystem stabilizer, PSS) in the excitation regulator of a conventional synchronous generator set. However, after a large number of conventional synchronous generators are replaced by photovoltaic power generation systems in the future, photovoltaic grid-connected control also needs to have the above-mentioned PSS function. Photovoltaic units con...

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Problems solved by technology

Photovoltaic units connected to the grid through power electronic converters have large power fluctuations. If the photovoltaic system does not have low-voltage ride-through capability (low-voltage ride-through capability refers to the The ability to continue grid-connected power generation), after decoupling (that is, after disconnecting from the grid system), it will intensify the oscillation power borne by the synchronous generator in the regional grid, which will more easily cause continuous oscillation of system power

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