VSC-HVDC不平衡故障控制策略的研究
发布时间：2018-09-17 06:40
【摘要】：与传统的直流输电不同，VSC-HVDC是一种以电压源型换流器(VSC)、可关断器件和脉宽调制(PWM)技术为基础的新型柔性直流输电技术。该技术采用基于脉宽调制技术的方法，能够灵活独立地控制有功功率和无功功率。换流站的整流器和逆变器具有良好的控制性能是VSC-HVDC系统安全稳定运行的保证，因此，VSC-HVDC换流器的控制成为核心问题备受关注。 首先，，从理论上介绍了VSC-HVDC系统的运行原理，并建立了在αβ两相静止坐标系下的暂态数学模型，分析了系统的功率交换控制原理，将与两端交流系统间的功率控制问题，转化为满足运行约束条件下电流有功分量和无功分量参考值的跟踪问题。 其次，设计了内环电流控制、外环功率控制的双闭环控制器，实现了对有功功率和无功功率的解耦控制。本文内环电流控制器引入了Terminal滑模控制，采用了VSC侧与交流侧复合功率控制方法，设计了αβ静止坐标下Terminal滑模内环控制器，实现对有功功率和无功功率的独立控制，提高了系统的抗扰动能力，通过Lyapunov理论证明了该控制器作用下闭环系统的稳定性，保证了其在电压不平衡条件下的暂态稳定性，同时加入VDCOL控制器，大大减少了直流过电压、欠电压现象的产生，提高了系统的抗扰动能力。 最后，利用PSCAD/EMTDC软件搭建了双端VSC-HVDC系统仿真模型，通过对VSC-HVDC系统与两端交流系统的功率交换及交流系统发生各种故障进行仿真分析，验证了所设计控制器的有效性。
[Abstract]:VSC-HVDC is a new flexible DC transmission technology based on (VSC), turn-off device and pulse width modulation (PWM) technology. The method based on pulse width modulation can control active and reactive power flexibly and independently. The good control performance of rectifier and inverter in converter station is the guarantee of safe and stable operation of VSC-HVDC system, so the control of VSC-HVDC converter has become the core problem. Firstly, the operation principle of VSC-HVDC system is introduced theoretically, and the transient mathematical model in 伪 尾 two-phase stationary coordinate system is established. The power exchange control principle of the system is analyzed. It is transformed into the tracking problem of the reference values of active and reactive components of current under the condition of operating constraints. Secondly, a double closed loop controller is designed for current control in inner loop and power control in outer loop, which realizes decoupling control of active power and reactive power. In this paper, the Terminal sliding mode control is introduced into the inner loop current controller, the compound power control method of VSC side and AC side is adopted, and the Terminal sliding mode inner loop controller in 伪 尾 static coordinates is designed to realize the independent control of active power and reactive power. The anti-disturbance ability of the system is improved. The stability of the closed-loop system under the action of the controller is proved by Lyapunov theory, and the transient stability of the closed-loop system under the condition of voltage unbalance is guaranteed. At the same time, the DC overvoltage is greatly reduced by adding the VDCOL controller. The phenomenon of undervoltage improves the anti-disturbance ability of the system. Finally, the simulation model of two-terminal VSC-HVDC system is built by using PSCAD/EMTDC software. The effectiveness of the designed controller is verified by the simulation and analysis of the power exchange between VSC-HVDC system and AC system and the fault of AC system.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1
[Abstract]:VSC-HVDC is a new flexible DC transmission technology based on (VSC), turn-off device and pulse width modulation (PWM) technology. The method based on pulse width modulation can control active and reactive power flexibly and independently. The good control performance of rectifier and inverter in converter station is the guarantee of safe and stable operation of VSC-HVDC system, so the control of VSC-HVDC converter has become the core problem. Firstly, the operation principle of VSC-HVDC system is introduced theoretically, and the transient mathematical model in 伪 尾 two-phase stationary coordinate system is established. The power exchange control principle of the system is analyzed. It is transformed into the tracking problem of the reference values of active and reactive components of current under the condition of operating constraints. Secondly, a double closed loop controller is designed for current control in inner loop and power control in outer loop, which realizes decoupling control of active power and reactive power. In this paper, the Terminal sliding mode control is introduced into the inner loop current controller, the compound power control method of VSC side and AC side is adopted, and the Terminal sliding mode inner loop controller in 伪 尾 static coordinates is designed to realize the independent control of active power and reactive power. The anti-disturbance ability of the system is improved. The stability of the closed-loop system under the action of the controller is proved by Lyapunov theory, and the transient stability of the closed-loop system under the condition of voltage unbalance is guaranteed. At the same time, the DC overvoltage is greatly reduced by adding the VDCOL controller. The phenomenon of undervoltage improves the anti-disturbance ability of the system. Finally, the simulation model of two-terminal VSC-HVDC system is built by using PSCAD/EMTDC software. The effectiveness of the designed controller is verified by the simulation and analysis of the power exchange between VSC-HVDC system and AC system and the fault of AC system.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1
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