为解决交直流双路接入的孤岛供电系统在交流线路因故障退出运行时出现的功率不平衡问题，在分析孤岛供电系统联网与孤岛运行控制策略的基础上，提出了一种基于虚拟同步控制的模块化多电平换流器型高压直流输电（modular multilevel converter based high voltage direct current，MMC-HVDC）孤岛供电系统交流故障穿越协调控制策略，实现自消纳场景和非自消纳场景下的功率协调。针对自消纳场景，提出了模块化多电平换流器（modular multilevel converter ，MMC）功率转带控制方法，仅通过增加其输出功率消纳系统功率缺额，有效降低不平衡功率的影响范围；针对非自消纳场景，设计了MMC与风电场共同参与不平衡功率调节的协调控制策略，控制MMC工作于最大功率输出状态，并利用风机的功率调节能力通过减速增载弥补剩余功率缺额，维持孤岛系统的功率平衡。最后，对所提协调控制策略的有效性进行仿真验证，结果表明，该策略能够实现孤岛供电系统由联网向孤岛运行的平滑转换，可有效提高其安全稳定运行能力。

In order to solve the power imbalance problem of island VSC-HVDC links operating in parallel with AC line when the AC line is out of operation due to a fault， according to the analysis on grid-connected and the island operation control strategy of the island power supply system， a virtual synchronous control based AC fault ride-through coordination control strategy for MMC-HVDC island power supply system is proposed to realize power coordination in self-consumption and non-self-consumption scenarios. Aiming at the self-consumption scenario， a method for MMC power transfer control is proposed， which reduces the power shortage of the system only by increasing its output power， and can effectively reduce the influence range of unbalanced power. Aiming at the non-self-consumption scenario， a coordinated control strategy for MMC and wind farms to participate in unbalanced power regulation is designed to control the MMC to work at the maximum power output， and the power adjustment capability of the wind turbine is used to compensate for the remaining power deficit through over-speed load-shedding to maintain the power balance of the island system. Finally， the effectiveness of the proposed coordinated control strategy is simulated and verified. The results show that the strategy can realize the smooth transition of island power supply system from grid-connected to island operation， and can effectively improve its safe and stable operation capability.

近年来，在碳达峰目标与碳中和愿景下，海上风电在我国取得了长足的发展。分析了我国目前海上风电的发展现状与未来规划，对海上风电装机规模、新增机型以及采用的技术路线进行了汇总。重点介绍了海上风电基础型式、防腐技术和运维技术，其中，漂浮式海上风电是基础型式研究的重点，运维巡检和运维管理系统是风电运维技术研究的重点。通过分析海上风电的发展状况，整理了各项技术的主要技术路线和先进成果。最后，基于目前国内的技术发展现状及需求，对我国海上风电未来发展趋势进行展望。

Under the carbon peak goal and carbon neutral vision, offshore wind power has made great progress in China in recent years. The current development status and future planning of offshore wind power in China were analyzed, and the installed capacity of offshore wind power, new models and adopted technical routes were summarized. The paper focused on the basic type, anti-corrosion technology, and operation and maintenance technology of offshore wind power. The floating offshore wind power was the focus of basic type research. The operation and maintenance inspection and operation and maintenance management system was the focus of wind power operation and maintenance technology research. By analyzing the development status of offshore wind power, the main technical routes and advanced achievements of each technology were sorted out. Finally, based on the current domestic technology development status and demand, the future development trend of China’s offshore wind power was prospected.

2021年10月江苏如东海上风电柔直工程(简称“如东工程”)进行海上换流站带单台、双台联接变空载解锁试验时,海上换流站交流系统电压分别出现2 500 Hz、2 000 Hz谐振。对如东工程的柔直系统阻抗、交流系统阻抗及其交互特性进行了详细分析,仿真结果证实了系统于该频段确有谐振风险,揭示了如东工程谐振机理。谐振抑制方面,提出了一种基于电压前馈环节比例谐振控制的有源谐振抑制方法,可显著降低柔直系统高频段负阻尼,通过仿真结果和如东工程现场实施证明了该方法的有效性。同时提出了一种基于幅相校正器装置的无源谐振抑制方法,可改善柔直系统与馈入系统全频段阻抗特性,基于如东工程参数的仿真结果显示该方法可全频段抑制系统谐振,有望彻底解决后续柔直系统谐振问题。

In October 2021, during a no-load unlocking test on an offshore converter station with single- and double-connected transformers, an AC system voltage resonance of 2500 Hz or 2000 Hz was detected at the Rudong Offshore Wind Power Flexible Direct Project. This paper provides a detailed analysis of the impedance of flexible DC and AC systems and their interaction characteristics. The simulation results confirmed that the system was at risk of resonance in this frequency band, and the resonance mechanism was revealed. To address this resonance issue, an active resonance suppression method based on proportional resonance control of the voltage feedforward link was proposed in this study, which can significantly reduce the high-frequency negative damping of flexible straight systems. Simultaneously, a passive resonance suppression method based on a correction device for amplitude and phase angle was also proposed to improve the full-band impedance characteristics of the flexible direct system and the feeding system. The simulation results obtained using the Rudong engineering parameters show that this method can suppress system resonance in the full frequency band and is expected to completely solve the resonance problem of the follow-up flexible DC system. Thus, the simulation results and on-site implementation of the Rudong project proved the effectiveness of the method.

统计并分析了海上风电机组叶片、主轴、电气系统、控制系统等关键部件和系统的技术现状及国产化状态，针对目前海上风电机组部件与系统中存在的国产化弱项，采用理论分析、材料/部件选型、部件研制、测试验证、整体组装的思路，进行叶片、主轴承、变流器、可编程逻辑控制器(programmable logic controller，PLC)等部件和系统的国产化研制，并采用研制的国产化部件和系统进行5 MW国产化海上风电机组装配，该机组的国产化率达到95%以上。结果表明：海上风电机组的大部分部件与系统具备国产化条件，部分设计(如叶片设计等)所用工业软件仍依赖进口，少部分核心元器件国内仍然缺失。

This paper analyzed the localization status of key components and systems in offshore wind turbines such as blades, spindles, electrical systems, and control systems.In view of the localization weaknesses existing in the components and systems of offshore wind turbines, the localization of blades, main bearings, converters and programmable logic controller (PLC) was carried out by using the ideas of theoretical analysis, material/component selection, component development, test verification and overall assembly, and 5 MW offshore wind turbines were assembled with the developed localization components and systems. The localization rate of the unit was more than 95%. The results show that most of the components and systems of offshore wind turbines have the conditions for localization, but some technologies, such as blade design, still rely on imports, and a few core components are still missing in China.

针对逆变型新能源场站柔性直流送出系统交流线路差动保护灵敏度降低问题,提出了一种基于改进判据的差动保护优化方案。利用逆变型新能源场站柔性直流送出系统交流线路故障特征,分析交流线路差动保护的适应性,正常区内故障时,将制动分量设为0,提升保护的灵敏性,当两侧相角差超90°时,判据中加入两侧电流相角差来削减灵敏性降低程度;与直接降低制动系数的方法相比,优化方案可以通过改变参数来兼顾差动保护的可靠性,且优化方案不受逆变型新能源场站外接系统强弱影响,适用范围更广;最后,利用PSCAD仿真软件搭建了逆变型新能源场站接入张北四端柔性直流系统模型,仿真验证了优化方案的有效性。

In order to reduce the sensitivity of AC line differential protection in flexible DC transmission system of inverter new energy station, an optimization scheme of differential protection based on improved criterion is proposed. Firstly, according to the AC line fault characteristics of the flexible DC transmission system of the inverter new energy station, the adaptability of the AC line differential protection is analyzed. In case of fault in the normal area, the braking component is set to 0 to improve the sensitivity of the protection. When the phase angle difference on both sides exceeds 90°, the current phase angle difference on both sides is added to the criterion to reduce the reduction of sensitivity. Then, compared with the method of directly reducing the braking coefficient, the optimization scheme can take into account the reliability of differential protection by changing parameters, and the optimization scheme is not affected by the strength of the external system of the inverter new energy station. Finally, the 4-terminal flexible DC system model of inverter new energy station connected to Zhangbei is built in PSCAD simulation software, and the simulation verifies the effectiveness of the optimization scheme.