Enabling a Robust Future HVDC Grid

高压直流输电（HVDC）系统在能源传输方面的应用越来越广泛。与交流传输相比，直流传输具有更低的功耗，可以起到防火墙的作用，从而防止危险干扰在大网络中级联传播。这一特点有利于可再生能源的接口。由于半导体技术的最新进展和新的电路拓扑，如多电平模块化变换器（MMC），克服了过去使用的线路整流变换器（LCC）的不足，高压直流系统正在经历一场革命性的变革。高压直流渗透的增加导致了多馈入配置，其中多个高压直流变流器馈入同一个交流系统，具有潜在的不利相互作用。******研究的长期目标是研究新的控制方法和配置的高压直流输电系统，使未来的高压直流电网更有效和弹性。为了做到这一点，“发现基金”将研究三个主要方向。******首先，该研究将尝试通过协调控制多个变流器来改善变流器的行为，无论是在多馈入还是直流电网配置中。一个感兴趣的领域将是通过协调附近转换器的控制来降低LCC转换器换相失败的风险。由于这些现象是高度非线性的，因此主要的研究方法将是利用蒙特卡罗模拟和非线性优化算法监督下的电磁瞬态模拟。******其次，研究将探讨高压直流变流器阻尼网络中的危险振荡和防止不稳定的能力。将研究利用远程转换器之间信息传输的广域控制方法。然而，重要的是要确保系统对工作点变化、信号传输延迟和通信丢失具有鲁棒性。将使用小信号建模与最新的鲁棒控制方法相结合。利用MMC电容器中储存的能量来控制MMC的新方法很有前景。******第三，该研究将调查新的HVDC控制方法，用于从偏远的海上发电厂疏散电力，并为偏远地区提供能源，如石油平台。提出的方法包括自主控制算法，赋予变频器类似惯性的行为，使其具有频率下降特性。其他方法包括直接控制，其中转换器的锁相环适当同步。******这项研究将在加拿大和其他地方带来更低的损失和弹性的能源传输网络。它是与加拿大几家公用事业和咨询公司合作进行的，从而提高了它们的竞争力。＊＊＊＊＊

High Voltage Direct Current Transmission (HVDC) Systems are seeing increasing use for the transport of energy. Compared with ac transmission, dc transmission has lower power loss and can perform the role of a firewall, thereby preventing the cascading propagation of dangerous disturbances across a large network. This feature facilitates the interfacing of renewable energy resources. HVDC Systems are undergoing a revolutionary transformation due to recent advances in semiconductor technology and new circuit topologies such as the multilevel modular converter (MMC), which overcome the deficiencies of line commutated converters (LCC) used in the past. The increased HVDC penetration is resulting in multi-infeed configurations where several HVDC converters feed into the same ac system, with the potential for adverse interactions. ******The long-term objective of the research is to investigate new control methods and configurations for HVDC Transmission Systems to make the future HVDC grid more effective and resilient. In order to do this, the Discovery Grant will investigate three broad directions. ******Firstly, the research will attempt to improve converter behavior by co-ordinated control of the multiple converters, either in a multi-infeed or dc grid configuration. One area of interest will be to reduce the risk of commutation failure in LCC converters by coordinating the controls of nearby converters. As the phenomena are highly-non-linear, the primary study approach will be to use electromagnetic-transient simulation supervised by Monte Carlo simulation and non-linear optimization algorithms. ******Secondly, the research will investigate the ability of HVDC converters to damp dangerous oscillations in the network and prevent instability. Wide-area control methods will be investigated which use information transmission between remote converters. However, it is important to ensure that the system is robust to operating point changes, signal transmission latency and loss of communication. Small signal modeling coupled with recent robust control approaches will be used. Novel ways of controlling the MMCs such as using the stored energy in the MMC's capacitors appear promising.******Thirdly the research will investigate new control methods for HVDC has been used for evacuating power from remote offshore power plants and for providing energy to remote locations such as oil platforms. Proposed approaches would include autonomous control algorithms that impart inertia-like behavior to the converters to operate them with a frequency droop characteristic. Other approaches include direct control where the phase locked loops of the converters are properly synchronized.******The research will result in lower loses and resilient energy transmission networks in Canada and elsewhere. It be carried out in collaboration with several Canadian utilities and consulting companies, thereby improving their competitiveness. *****