[论文解读] North Sea Wind Power Hub: System Configurations, Grid Implementation and Techno-economic Assessment

George S. Misyris, Thierry Van Cutsem+9 more|arXiv (Cornell University)|Jun 10, 2020

Microgrid Control and Optimization参考文献 11被引用 5

一句话总结

本文评估了北海风电枢纽概念，分析了海上电网配置、低惯性或零惯性下的系统运行，以及使用EMT和相量模型的模型保真度。研究发现，额定频率的高压直流电网最具成本效益；零惯性系统虽提供更好的阻尼，但需配备同步调相机以缓解故障影响；若电网特征频率充分阻尼，相量模型已足够精确。

ABSTRACT

In 2017, Energinet and TenneT, the Danish and Dutch Transmission System Operators (TSOs), have announced the North Sea Wind Power Hub (NSWPH) project. The project aims at increasing by 36 GW the North Sea offshore wind capacity, with an artificial island collecting all the power produced by wind turbines and several HVDC links transmitting this power to the onshore grids. This project brings together new opportunities and new challenges, both from a technical and economic point of view. In this regard, this paper presents three analyses regarding the design and operation of such an offshore system. First, we perform a techno-economic assessment of different grid configurations for the collection of the power produced by wind farms and its transmission to the hub. In this analysis, two frequencies and two voltage levels for the operation of the offshore grid are investigated. Our findings show that the nominal-frequency high-voltage option is the more suitable, as low-frequency does not bring any advantage and low-voltage would results in higher costs. The second analysis is related to the differences in operating the system with low- or zero-inertia; different dynamic studies are performed for each configuration to identify proper control actions and their stability properties. Comparing the outcomes of the simulations, we observed that voltage and frequency oscillations are better damped in the zero-inertia system; however, the risk of propagating offshore faults in the connected onshore grids is mitigated with the inclusion of the synchronous condensers. Lastly, a comparison of ElectroMagnetic Transient (EMT) and phasor-mode (also known as RMS) models is presented, in order to understand their appropriateness of simulating low- and zero- inertia systems. The results show that phasor approximation modelling can be used, as long as eigen-frequencies in power network are well damped.

研究动机与目标

• 评估北海风电枢纽海上电网配置在成本与技术可行性方面的差异。
• 评估低惯性和零惯性运行条件下系统的稳定性与控制需求。
• 比较电磁暂态（EMT）模型与相量模型（RMS）在低惯性和零惯性系统中的准确性与适用性。
• 基于技经与动态性能，确定海上直流电网的最优电压与频率水平。
• 确定同步调相机在零惯性系统中缓解故障传播风险的作用。

提出的方法

• 开展技经评估，比较海上交直流电网的两种电压等级（高与低）和两种频率（额定与低）。
• 进行动态仿真，分析低惯性和零惯性运行下的电压与频率振荡。
• 在零惯性系统中引入同步调相机，评估其对故障 ride-through 和稳定性的影响。
• 比较电磁暂态（EMT）模型与相量模型（RMS），评估其在暂态稳定性研究中的模型保真度。
• 利用特征值分析评估网络模式的阻尼特性，确定相量模型有效的条件。
• 使用电力系统仿真工具，结合高压直流链路与风电场汇集系统的详细建模，分析不同电网配置下的系统性能。

实验结果

研究问题

• RQ1 在北海风电枢纽的海上电网中，电压等级与频率的何种组合能在技术性能与成本之间实现最佳平衡？
• RQ2 与低惯性运行相比，零惯性运行对电压与频率稳定性有何影响？
• RQ3 为确保零惯性海上电网的稳定运行，需要何种控制策略？同步调相机如何提升故障 ride-through 能力？
• RQ4 在何种条件下，相量模型（RMS）能够准确表征低惯性和零惯性系统的动态特性？
• RQ5 在不同惯性条件下，海上电网的故障是否会传播至陆上电网，其影响如何？

主要发现

• 额定频率的高压直流电网配置最具成本效益，因低频无优势，而低电压显著增加成本。
• 在动态仿真中，零惯性系统相较于低惯性系统表现出更优的电压与频率振荡阻尼特性。
• 在零惯性系统中，同步调相机的引入可有效缓解故障向陆上电网传播的风险。
• 只要电网特征频率充分阻尼，相量模型（RMS）即可准确模拟低惯性和零惯性系统的动态行为。
• 低频运行未带来技术优势，反而导致损耗增加与设备成本上升，因此不如额定频率运行有利。
• 当采用高电压与额定频率时，海上电网的技术与经济性能最优，支持北海风电枢纽概念的可行性。