On the Optimality of Voltage Unbalance Attenuation by Inverters
On the Optimality of Voltage Unbalance Attenuation by Inverters
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DOI：
10.1109/tste.2022.3163074
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发表时间：
2021-09
影响因子：
8.8
通讯作者：
Yifei Guo;B. Pal;R. Jabr
中科院分区：
文献类型：
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作者：
Yifei Guo;B. Pal;R. Jabr
在本文中，我们研究了基于逆变器的资源（IBR）的控制，以实现最佳电压不平衡衰减（OVUA）。该问题被表述为定制 dq 框架下的优化程序，该程序在电流、有功功率、同步稳定性和可行性约束下最小化公共耦合点 (PCC) 处的负序电压。该程序本质上是非凸且棘手的。因此，为了保证最优性，通过利用分析优化来执行严格的最优性分析。分析分为两种情况：VU完全缓解和VU部分衰减。对于前一种情况，我们直接求解原始程序，因为所得的 VU 可以立即推导。对于后一种情况，直接解决问题就变得非常困难。因此，我们在某些条件下将程序重新表述为等效但更易于处理的形式，通过该形式可以得出分析最优值。研究发现，最佳轨迹具有三个阶段（O1-O3），具体取决于两个临界边界条件（C1 和 C2）。我们通过开发 OVUA 控制器来实现光伏 (PV) 存储系统的优化。所提出的方法通过不同 VU 条件下的动态模拟进行了论证，并与几种现有实践进行了比较。最后，我们讨论了所提出的解决方案在多 IBR 系统中的扩展。
In this paper, we investigate the control of inverter-based resources (IBRs) for optimal voltage unbalance attenuation (OVUA). This problem is formulated as an optimization program under a tailored dq-frame, which minimizes the negative-sequence voltage at the point of common coupling (PCC) subject to the current, active power, synchronization stability, and feasibility constraints. The program is inherently nonconvex and intractable. So, to guarantee the optimality, a rigorous optimality analysis is performed by leveraging analytical optimization. The analysis is divided into two cases: full mitigation of VU and partial attenuation of VU. For the former case, we directly solve the original program since the resultant VU is immediately deducible. For the latter one, directly solving the problem becomes very hard. Thus, we reformulate the program into an equivalent but more tractable form under certain conditions, by which the analytical optimum can be derived. It is found that the optimum trajectory has three stages (O1–O3), depending on two critical boundary conditions (C1 and C2). We implement the optimum with a photovoltaic (PV)-storage system by developing an OVUA controller. The proposed approach is demonstrated by dynamic simulations under different VU conditions and is compared with several existing practices. Finally, we discuss the extension of the proposed solution in a multi-IBR system.