VSC-HVDC在城市电网中可行性及适应性研究

发布时间：2018-04-24 18:44

本文选题：VSC-HVDC + 城市电网　；参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：我国能源资源和负荷中心呈逆向分布,为优化资源配置,需从西部和北部的能源基地将电能输送到中东部负荷中心。高压直流输电技术在远距离大容量的跨区输送电能方面具有优势,因此发展特高压输电是实现清洁替代的基础,是构建全球能源互联网的关键。但是特高压直流输电直接接入负荷中心,由于落点集中且输送容量大,若发生直流故障,将造成大范围潮流的转移,严重威胁着受端电网的安全稳定性。基于电压源换流器的高压直流输电技术(voltage source converter based high voltage direct current,VSC-HVDC)能够克服传统直流输电技术的一些缺陷,在调节潮流、稳定电压等方面具有明显的优势,是向城市中心区域供电的最佳途径,能解决当前城市电网面临的诸如短路电流超标等现实问题,具有至关重要的意义。论文主要针对VSC-HVDC在城市电网的可行性和接入后的适应性问题进行研究。VSC-HVDC不需要受端电网提供换向电流,能够自关断,无换向失败的问题,理论上可工作在任何强度的电网,但是需要考虑VSC-HVDC的接入对受端电网运行安全稳定性的影响。通过分析VSC-HVDC接入弱交流电网的运行特性,搭建接入弱交流电网的数学模型,推导出最大输送功率公式,引入短路比(short-circuit ratio,SCR)的概念,分析接入交流电网的影响因素,求解出VSC-HVDC接入交流电网的临界短路比,并在PSD-BPA软件中利用实际电网数据搭建小型模型,验证了理论分析的正确性,为工程应用提供理论指导。同时,VSC-HVDC灵活调节潮流,可单独调节有功无功,在不改变电压极性和控制模式下,实现潮流反转,当电压下降或发生崩溃后,能够启动自身参考电压,快速恢复供电和黑启动。通过推导出VSC-HVDC在城市电网中的交直流系统的潮流模型,求解出VSC-HVDC在城市电网中故障下的最优潮流优化,并利用PSD-BPA软件中某城市实际模型进行求解分析。VSC-HVDC不需要交流侧提供无功功率,能根据电网的无功需求灵活地调节发出或吸收无功功率,动态补偿交流母线的无功功率,并稳定交流母线电压。通过在PSD-BPA软件中利用实际电网模型对故障下VSC-HVDC对系统电压的影响进行仿真分析。
[Abstract]:The energy resources and load centers in China are distributed in reverse direction. In order to optimize the allocation of resources, it is necessary to transfer electric energy from the energy bases in the west and north to the load centers in the central and eastern parts of China. High voltage direct current (HVDC) transmission technology has advantages in long-distance and large-capacity power transmission across regions. Therefore, the development of UHV transmission is the basis of clean substitution and the key to the construction of global energy Internet. However, when UHVDC is directly connected to the load center, if DC fault occurs, it will cause a large-scale power flow transfer, which will seriously threaten the safety and stability of the receiving power network because of the concentrated landing point and large transmission capacity. Voltage source converter based HVDC technology can overcome some defects of traditional HVDC technology and has obvious advantages in regulating power flow and stabilizing voltage. It is the best way to supply power to the central area of the city. It is of great significance to solve the current problems such as short circuit current exceeding the standard and so on. This paper mainly focuses on the feasibility and adaptability of VSC-HVDC in urban power network. VSC-HVDC does not need to provide commutation current from the receiving network, can turn off itself, and has no commutation failure. In theory, it can work in any power grid of any intensity. However, it is necessary to consider the influence of VSC-HVDC access on the security and stability of the receiving power network. Based on the analysis of the operation characteristics of VSC-HVDC access to weak AC power grid, the mathematical model of accessing weak AC power grid is built, the maximum transmission power formula is derived, the concept of short-circuit short-circuit SCR is introduced, and the influencing factors of accessing AC power network are analyzed. The critical short-circuit ratio of VSC-HVDC connected to AC power network is solved, and a small model is built by using actual power grid data in PSD-BPA software, which verifies the correctness of theoretical analysis and provides theoretical guidance for engineering application. At the same time, VSC-HVDC can adjust the power flow flexibly, can adjust the active and reactive power alone, and realize the power flow reversal without changing the voltage polarity and control mode. When the voltage drops or collapses, it can start its own reference voltage and quickly restore the power supply and black start. By deducing the power flow model of AC / DC system of VSC-HVDC in urban power network, the optimal power flow optimization of VSC-HVDC in urban power network is obtained. VSC-HVDC does not need AC side to provide reactive power, it can flexibly adjust or absorb reactive power according to the reactive power demand of power grid, and dynamically compensate reactive power of AC bus. And stable AC bus voltage. The effect of VSC-HVDC on system voltage under fault is simulated and analyzed by using the actual power network model in PSD-BPA software.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM721.1

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