基于一致性算法的电压频率恢复与无功分配

发布时间：2018-06-02 08:16

  本文选题：微电网 + 下垂控制　； 参考：《沈阳农业大学》2017年硕士论文

【摘要】：在全球更为重视以清洁能源为主体的分布式发电的今天,微电网是应用于实际、将可再生能源发电大规模并网的有效方式,是将分布式电源和传统电力系统相融合的桥梁。与传统电网相比,微电网虽然可以提高供电的稳定性、可靠性以及电能质量,但是由于分布式发电所具有的间歇性和随机性等带来的潮流不稳定的影响,暴露了其局限性。而功率的精确分配、维持电压和频率的稳定等逆变器控制也逐渐成为了微电网领域中最为热门的研究方向之一。传统的集中控制方法无法解决现今多种模式运行的微电网带来的低可控、信息收集难引起的复杂系统控制,但基于多智能体的分布式控制法对于目前大量分布式并网引发的问题解决有着明显优势。本文通过多智能体控制理论应用于微电网多逆变器的分布式控制当中,获得了使用与微电网孤岛运行时分布式发电的功率精确分配、微电网二级电压与频率的恢复控制等成果。具体内容如下:针对传统的下垂控制引起电压、频率偏移的问题和考虑线路阻抗不匹配的实际情况,从微电网和分布式发电建模,二级控制器上存在的局限性分析出发,提出了基于一致性算法的分布式二级电压,频率恢复控制策略。在二级频率恢复控制中,提出了考虑有功功率精确分配的分布式二级频率恢复控制器,在二级电压恢复控制中,提出了考虑线路参数不平衡,利用动态一致性控制的分布式平均电压恢复控制策略。仿真验证了提出的分布式二级控制方法能够保证电压幅值和频率恢复。针对传统的下垂控制无功功率分配不精确的问题和考虑线路阻抗不匹配的实际情况,从传统电压/无功下垂控制以及微电网传输线路阻抗特性等方面分析了负荷无功功率分配、微电网环流抑制的机理。通过虚拟阻抗调整,实现传统的下垂控制方法导致有功功率和无功功率之间的解耦,建立了基于一致性算法的无功功率分配控制策略。该策略通过多智能体一致性算法发现无功功率分配误差。使无功分配误差自适应调整虚拟阻抗,从而得到按照分布式发电容量反比例的等效线路阻抗。根据基于虚拟阻抗调整的无功功率按比例分配原理,实现多分布式发电之间的负荷无功功率精确分配。
[Abstract]:In today's world where more attention is paid to distributed generation with clean energy as the main body, microgrid is an effective way to connect renewable energy generation to the grid on a large scale, and it is a bridge between distributed power generation and traditional power system. Compared with the traditional power grid, microgrid can improve the stability, reliability and power quality of power supply, but its limitation is exposed because of the impact of power flow instability caused by the intermittent and randomness of distributed generation. The accurate distribution of power, the maintenance of voltage and frequency stability and other inverter control has gradually become one of the hottest research directions in the field of microgrid. The traditional centralized control method can not solve the complex system control caused by the low controllability and information collection caused by the multi-mode microgrid. But the distributed control method based on multi-agent has obvious advantages to solve the problems caused by distributed grid connection. In this paper, the theory of multi-agent control is applied to the distributed control of microgrid multi-inverter, and the results are obtained, such as accurate power distribution of distributed generation with isolated island operation of micro-grid, restoration control of two-stage voltage and frequency of micro-grid, and so on. The main contents are as follows: aiming at the problems of voltage and frequency offset caused by traditional droop control and considering the actual situation of line impedance mismatch, the paper analyzes the limitations of microgrid and distributed generation modeling, and the limitation of secondary controller. A distributed secondary voltage and frequency recovery control strategy based on consistency algorithm is proposed. In the two-stage frequency recovery control, a distributed second-stage frequency recovery controller considering the accurate allocation of active power is proposed. In the two-stage voltage recovery control, the unbalanced circuit parameters are considered. Distributed average voltage recovery control strategy based on dynamic consistency control. Simulation results show that the proposed distributed secondary control method can guarantee the voltage amplitude and frequency recovery. Aiming at the problem of inaccurate reactive power distribution in traditional droop control and considering the actual situation of line impedance mismatch, the load reactive power distribution is analyzed from the aspects of traditional voltage / reactive droop control and impedance characteristics of transmission line in microgrid. The mechanism of microgrid circulation suppression. The traditional droop control method leads to decoupling between active power and reactive power through virtual impedance adjustment. The reactive power allocation control strategy based on consistent algorithm is established. In this strategy, reactive power allocation error is detected by multi-agent consistency algorithm. The virtual impedance is adjusted adaptively by the reactive power distribution error, and the equivalent line impedance is obtained according to the inverse ratio of the distributed generation capacity. According to the principle of proportional distribution of reactive power based on virtual impedance adjustment, the accurate distribution of reactive power among multiple distributed generation is realized.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727;TM712
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本文编号：1968071