A voltage control method for common connection point of photovoltaic system considering three-phase unbalance

Abstract

The invention discloses a photovoltaic system point of common coupling voltage control method considering three-phase imbalance. The method includes following steps: calculating a voltage deviation ofa point of common coupling of nodes, and determining whether the voltage deviation of the point of common coupling is in accordance with a voltage deviation standard; if the voltage deviation is greater than a maximum voltage deviation standard, performing voltage reduction processing through a photovoltaic inverter and / or an energy storage device; and if the voltage deviation is less than a minimum voltage deviation standard, performing boosting processing through the photovoltaic inverter and / or the energy storage device. According to the method, continuous control of the voltage of the point of common coupling is realized through the coordination of the active power and the reactive power of the photovoltaic inverter and the energy storage device, the consumption of new energy is guaranteed, the reactive adjusting capability of the photovoltaic inverter is equivalently increased, the problem of three-phase imbalance is improved, and the electric energy quality is improved.

Description

technical field [0001] The invention relates to the field of photovoltaic power generation, in particular to a method for controlling the voltage of a common connection point of a photovoltaic system in consideration of three-phase imbalance. Background technique [0002] In recent years, with the maturity of photovoltaic power generation technology, the penetration rate of distributed photovoltaic in distribution network, especially in low-voltage distribution network, has been increasing. In the distribution network with high photovoltaic penetration rate, especially in the weak radial low-voltage distribution network, the fluctuation and randomness of photovoltaic output will lead to large fluctuations in the voltage of the common connection point of the photovoltaic system, which will affect the normal operation of the distribution network. to adversely affect. [0003] The current distribution network voltage control generally adopts traditional adjustment methods, inc...

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Problems solved by technology

[0017] However, the photovoltaic inverter only controls the voltage of the grid-connected point, and cannot solve the problem of the voltage exceeding the limit at the common connection point. Moreover, relying solely on the photovoltaic inverter to control the voltage, reducing active power will reduce energy utilization, and the ability to adjust reactive power is limited.

At the same time, the above control methods do not consider the three-phase unbalance problem at the common connection point, and most of the household low-voltage photovoltaics are single-phase grid-connected devices, and blind adjustment may aggravate the three-phase unbalance problem

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