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Grid-connected converter series virtual impedance control method

A virtual impedance and inverter technology, which is applied in the control of grid-connected inverters and virtual inertial control of grid-connected inverters in series with virtual impedance control, can solve problems such as weakening of the inhibition effect.

Active Publication Date: 2020-01-31
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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Problems solved by technology

Zhang Jihong and others disclosed a DC microgrid bus voltage fluctuation control strategy in the Journal of Electrotechnical Society, 2018, 33(06): 1238-1246. Hierarchical coordinated control strategy, which can be suppressed according to the fluctuation amplitude of the DC bus voltage on the basis of considering the state of charge. This method is suitable for energy storage devices, and the suppression effect will be weakened in the grid-connected state of the microgrid

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  • Grid-connected converter series virtual impedance control method

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Embodiment Construction

[0058] An improved method for virtual inertial control of grid-connected converter series virtual impedance, such as figure 1 As shown, it is characterized in that: comprising the following steps:

[0059] Step 1: Establish a DC microgrid system: the DC microgrid system consists of a DC bus, a wind turbine, a battery, an AC load, an AC-DC converter, a DC-DC converter, a grid-connected converter, an AC grid, AC measuring element, DC measuring element, filter and control system; AC load is connected to DC bus through AC-DC converter, storage battery is connected to DC bus through DC-DC converter, and wind turbine is converted through AC-DC connected to the DC bus, the AC power grid is connected to the DC bus through the grid-connected converter after passing through the filter, the input terminals of the control system are respectively connected to the output terminals of the DC measuring element and the AC measuring element, and the output terminals are connected to the The in...

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Abstract

The invention discloses a grid-connected converter series virtual impedance method for virtual inertia control. The method comprises the steps that a direct current micro-grid system is established; signal measurement and processing are carried out; small signal analysis is carried out on a reference current equation; small signal analysis is carried out on a grid-connected converter mathematicalmodel and a current inner loop control model; small signal analysis is carried out a power equation; output impedance Zo(s) is calculated; a spike function is extracted and multiplied with a low-passfilter to form a compensation amount; series virtual impedance is applied to a current reference value; PI control and feedforward decoupling control are carried out; alpha beta transform and SVPWM modulation are carried out. According to the invention, the method has the advantages of simple structure and high efficiency; when the direct current micro-grid system is unstable, the control goals ofincreasing system damping, suppressing direct current voltage oscillation, and ensuring voltage quality during steady-state operation are realized.

Description

technical field [0001] The invention relates to a control method of a grid-connected converter, in particular to a method for controlling a series virtual impedance of a grid-connected converter with virtual inertia control, and belongs to the technical field of power supply control. Background technique [0002] Driven by the energy crisis and environmental pollution, renewable energy has been developed and utilized on a large scale. DC microgrid is the main way of distributed power supply, and it has obvious advantages such as simple control, low operating cost, no need to consider phase synchronization and reactive power circulation, etc., and has attracted the attention of many research institutions at home and abroad. The DC bus voltage is the only indicator to measure the stable operation of the DC microgrid. The DC bus is the medium for energy collection and power exchange. A large number of distributed power sources have negative impedance characteristics similar to...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J1/10H02J1/14
CPCH02J1/10H02J1/14
Inventor 朱晓荣韩丹慧
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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