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A capacitive reactive current extraction method applied to three-phase three-wire system

A capacitive reactive power, three-phase three-wire technology, applied in reactive power compensation, reactive power adjustment/elimination/compensation, electrical components, etc., can solve problems such as interference, accuracy impact, and extracted component distortion

Inactive Publication Date: 2021-06-08
TIANJIN UNIV
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Problems solved by technology

On the one hand, this kind of method is affected by the accuracy of the voltage phase-locked link. When the voltage contains harmonic components, the extracted components will be distorted; on the other hand, a large number of trigonometric function calculations are required.
There is also a method to calculate the reactive current by calculating the symmetrical active component in the three-phase load current, and subtracting the active component from the load current to calculate the reactive current; but when the load current contains other components, the result of calculating the reactive current component based on this method is usually will be disturbed

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  • A capacitive reactive current extraction method applied to three-phase three-wire system
  • A capacitive reactive current extraction method applied to three-phase three-wire system
  • A capacitive reactive current extraction method applied to three-phase three-wire system

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Embodiment Construction

[0033] Attached below figure 2 The present invention is described with embodiment, specifically as follows:

[0034] (1) if figure 2 As shown, a capacitive symmetrical three-phase load is connected to a three-phase three-wire system. Generally speaking, it can be equivalent to a three-phase capacitive load (its capacitance value is C), and a three-phase resistive load (its resistance value is R )in parallel. Consider that besides the fundamental wave components, the grid voltage also contains harmonic components. Its ABC three-phase instantaneous voltage u a , u b , u c Expressions can be expressed as:

[0035]

[0036] where U 0 is the fundamental voltage amplitude, ω 0 is the fundamental voltage frequency; U e is the harmonic voltage amplitude, ω e is the harmonic voltage frequency, θ e is the initial phase of the harmonic voltage.

[0037] According to the load parameters C and R, its ABC three-phase instantaneous current i a i b i c Can be expressed as:...

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Abstract

The invention relates to a capacitive reactive current extraction method applied to a three-phase three-wire system. The steps are as follows: collecting load ABC three-phase instantaneous current and three-phase instantaneous voltage; The component u in the stationary coordinate system α , u β ; Find u separately α , u β Calculate the first order derivative of Q to get Q, when Q>0 is satisfied, the load current contains capacitive current component at this time, continue to calculate; calculate the capacitive current extraction coefficient B; calculate the capacitive reactive current in the two-phase static coordinate system ; Find the three-phase capacitive reactive current component. The invention can directly calculate and extract the capacitive current component in the load current without introducing a phase-locked loop to calculate the phase of the voltage when harmonic distortion occurs in the voltage.

Description

technical field [0001] The invention belongs to the field of power systems, and in particular relates to a method for extracting capacitive reactive current components in grid load currents in a three-phase three-wire grid. Background technique [0002] With the increase of load types in the power grid and the increasingly complex operation mode, the influence of the capacitive current component in the load current on the operation of the power grid cannot be ignored. Excessive capacitive current will lead to a voltage increase at the load access point and even endanger safe operation. Extracting the capacitive current component contained in the load current is of great significance for the analysis and management of power quality. [0003] The current common three-phase reactive current extraction algorithm is usually based on the phase-locked loop calculation of the load voltage phase, and based on this, the DQ transformation is performed on the three-phase load current, ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/01H02J3/18
CPCH02J3/01H02J3/1864Y02E40/30Y02E40/40
Inventor 李永丽靳伟孙广宇高岩
Owner TIANJIN UNIV
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