A Method for Extracting Positive Sequence Components of Three-phase Grid Voltage under Unbalanced Conditions
A technology of three-phase power grid and balanced conditions, applied in the direction of measuring current/voltage, measuring electrical variables, measuring devices, etc., can solve the problems of not being able to have both stability and speed at the same time, and achieve low hardware environment requirements, fast speed, and easy Achieved effect
Active Publication Date: 2017-09-22
ZHUHAI HENGQIN JIUYUAN POWER ELECTRONICS SCI &TECH CO LTD
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The above two methods cannot be stable and fast at the same time
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[0020] The present invention proposes a method for extracting positive sequence components of three-phase grid voltage under unbalanced conditions. The method includes the following steps:
[0021] (1) Isolate and sample the instantaneous voltage of the three-phase power grid through the voltage Hall sensor and the op amp conditioning circuit U a , U b , U c , in the case of removing zero-sequence components, the following relationship can be satisfied:
[0022]
[0023] in U ap , U bp , U cp Representing U a , U b , U c The positive sequence component of the three-phase voltage, U an , U bn , U cn Representing U a , U b , U c The negative sequence component of the three-phase voltage.
[0024] (2) Will U a , U b , U c The first-order inertial filtering is performed respectively, and the transfer function is , in order to facilitate the digital operation in the processor, the digital discrete equation of the first-order inertial filter i...
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The invention aims to provide an extraction method for three-phase network voltage positive-sequence components under an imbalance condition. The extraction method is high in speed, good in stability and low in requirement for the external hardware environment. Through combination of formula translation and a first-order inertial filtering method, a reasonable and effective positive-sequence separation method is provided and can meet the requirement for obtaining power network fundamental wave phase information through a current converter under the three-phase imbalance condition of a power network. Based on an ABC coordinate system, through performing detection operation and first-order inertial filtering on the instantaneous value of three-phase network voltage, the three-phase network voltage positive-sequence components are effectively extracted without converting under different coordinate systems; the algorithm is easier to implement in an embedded control system, and the requirement for the speed of an embedded processor is lower. The extraction method can be applied to the field of power electronics.
Description
technical field [0001] The invention relates to the field of power electronics—a control method for a new energy grid-connected converter and a power battery charge and discharge detection bidirectional converter device, in particular a method for extracting positive sequence components of a three-phase grid voltage under unbalanced conditions. Background technique [0002] In new energy grid-connected power generation and power battery charge and discharge detection equipment, in order to avoid affecting the power quality, it is usually necessary to detect the voltage and current phase of the grid. When the three phases are unbalanced, the conventional phase-locking method is used to monitor the grid Phase-locking is prone to failure. Therefore, in order to better balance the three-phase current control, it is necessary to separate the positive sequence of the three-phase voltage of the power grid, and better track the phase of the power grid through the positive sequence co...
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IPC IPC(8): G01R19/00
Inventor 何金伟屈世磊
Owner ZHUHAI HENGQIN JIUYUAN POWER ELECTRONICS SCI &TECH CO LTD