Sequence Domain SISO Equivalent Models of a Grid-Tied Voltage Source Converter System for Small-Signal Stability Analysis
Sequence Domain SISO Equivalent Models of a Grid-Tied Voltage Source Converter System for Small-Signal Stability Analysis
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DOI：
10.1109/tec.2017.2766217
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发表时间：
2018-06
影响因子：
4.9
通讯作者：
Chen Zhang;X. Cai;Atle Rygg;M. Molinas
中科院分区：
文献类型：
--
作者：
Chen Zhang;X. Cai;Atle Rygg;M. Molinas
本文提出了一种通用方法，用于将并网电压源变流器系统的多输入多输出 (MIMO) $dq$ 阻抗模型转换为其序列域单输入单输出 (SISO) 等效模型。由此推导出两种类型的SISO阻抗模型，一种是基于相对较强的$dq$对称网格假设（简化的SISO模型），另一种是基于闭环等效（精确的SISO模型）。事实证明，精确的SISO模型具有与MIMO模型相同的边际稳定性条件。这些模型的准确性根据 PSCAD/EMTDC 模拟中测量的阻抗进行评估，并分析了它们对稳定性的影响。研究结果表明，准确的 SISO 模型呈现出与 MIMO 模型相同的稳定性结论。然而，如果系统高度${\rm{dq}}$不对称，例如具有快速锁相环的VSC或主动控制电网，简化的SISO模型可能会导致不准确的结果。
This paper presents a generalized method for converting multi-input and multi-output (MIMO) $dq$ impedance model of a grid-tied voltage source converter system into its sequence domain single-input and single-output (SISO) equivalents. As a result, two types of SISO impedance models were derived, one of which was derived from relatively strong and $dq$ symmetric grid assumption (reduced SISO model) and the other was based on closed-loop equivalent (accurate SISO model). It was proven that the accurate SISO model has the same marginal stability condition as the MIMO model. Accuracy of these models is assessed with respect to the measured impedances in PSCAD/EMTDC simulations, their effects on stability are analyzed as well. Findings show that the accurate SISO model presents identical stability conclusions as the MIMO model. However, the reduced SISO model may lead to inaccurate results if the system is highly ${\rm{dq}}$ asymmetric, e.g., VSC with fast phase-locked loop or an actively controlled grid.