AN ANALYSIS OF HARMONIC DISTURBANCES IN DISTRIBUTION SYSTEMS CAUSED BY GRID-CONNECTED INVERTERS: EXPERIMENTAL VERIFICATION OF HIGH-ORDER HARMONIC RESONANCE
AN ANALYSIS OF HARMONIC DISTURBANCES IN DISTRIBUTION SYSTEMS CAUSED BY GRID-CONNECTED INVERTERS: EXPERIMENTAL VERIFICATION OF HIGH-ORDER HARMONIC RESONANCE
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发表时间：
2019
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影响因子：
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通讯作者：
N. Okada;Kenichiro
中科院分区：
文献类型：
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作者：
N. Okada;Kenichiro
在分布电源较多的中压配电系统中，并网逆变器的高次谐波（2kHz ~ 9kHz）引起了谐波干扰。以往的计算机仿真表明，即使逆变器的电流谐波满足电网规范推荐的抑制水平，电压谐波也可能超过配电系统的抑制水平。需要对扰动进行实验验证，阐明扰动的条件和机理。本文通过实验研究了不同开关频率和电网配置下并网逆变器的谐波特性。如果电网侧阻抗的串联谐振频率与逆变器的开关频率一致，则在并联电容器上观察到大的谐波电压。由于电网侧阻抗在串联谐振频率处减小，谐波电流从谐波滤波器泄漏，然后流入并联电容器。串联谐振频率受电网侧阻抗的影响，可以通过电路参数计算得到。
Harmonic disturbances caused by the high-order harmonics (2kHz ~ 9kHz) of grid-connected inverters were observed in the medium-voltage distribution systems which host a large amount of distributed generations. It was demonstrated by the previous computer simulations that voltage harmonics may exceed the suppression level of the distribution system even if the current harmonics of the inverters satisfy the suppression level recommended in the grid-code. It is required to validate the disturbance by the experiment along with clarifying its condition and mechanism. This research investigates harmonic characteristics of the grid-connected inverters by the experiment under different switching frequency and grid configurations. Large harmonic voltage is observed across the shunt capacitor if the series resonant frequency of the grid-side impedance coincides with the switching frequency of the inverter. Since the grid-side impedance decreases at the series resonant frequency, harmonic current leaks from the harmonic filter, and then it flows into the shunt capacitor. The series resonant frequency is influenced by the grid-side impedance, which can be calculated by the circuit parameters.