交直流混联电网大扰动稳定特性分析与控制策略研究

发布时间：2018-03-04 04:09

本文选题：稳定性　切入点：交直流混联系统　出处：《华北电力大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着西电东送和全国联网工程的实施,我国已逐步形成大区联网、特高压交直流混联输电的基本格局。在特高压交流建设初期,华北-华中电网通过单回特高压交流通道弱互联。四川网内故障容易引发交流特高压通道功率大幅波动是目前存在的突出稳定性问题。本文围绕这一迫切需要解决的实际问题,对交直流混联电网的稳定特性及安控策略做了深入研究。首先本文通过详细的稳定计算,全面分析了当前网架结构下引发华北-华中联络线波动的故障电网的稳定特性。在此基础上,详细分析了特高压通道大幅波动情况下系统中的能量流动和振荡特性,并由此得出了扰动轨迹特征的一般性结论：在受扰程度较为严重的情况下,联络线有功功率波动轨迹会出现“双峰”特征,该特征由联络线有功功率与功角、电压的函数关系决定。依据该特征,本文提出了一种基于联络线扰动轨迹特征的直流稳定控制策略。当系统稳定裕度严重下降,出现“双峰轨迹”的情况下,可在第一个峰值启动直流紧急控制,在第二个峰值系统稳定裕度显著提升时退出直流紧急控制。并验证了不同情况下,该控制策略的控制效果。为了削弱四川网内故障对华中-华北互联通道的影响。本文分析了四川电网火电机组开机方式对系统稳定性的影响。本文按作用对火电机组进行分类,给出了优化开机方式,并对其效果进行了验证。临近主干输电网火电机组增加开机容量,主要可通过改变转动惯量分布、削弱振荡模式叠加关系以及增强电网电压支撑,减少负荷释放功率两方面减少四川网故障对特高压电网冲击影响的效果。
[Abstract]:With the implementation of the West-East Power Transmission Project and the nationwide interconnection project, China has gradually formed the basic pattern of large-scale interconnection and UHV AC / DC hybrid transmission. In the early stage of UHV AC / DC construction, North China Central China Power Grid is weakly interconnected through a single UHV AC channel. It is a prominent stability problem that power fluctuation of AC UHV channel is easily caused by faults in Sichuan network. This paper revolves around this urgent practical problem which needs to be solved. The stability characteristics and safety control strategy of AC / DC hybrid power network are studied. First of all, through detailed stability calculation, this paper comprehensively analyzes the stability characteristics of the fault power network which causes the fluctuation of the tie-line between North China and Central China under the current grid structure. The characteristics of energy flow and oscillation in UHV channel with large fluctuations are analyzed in detail, and the general conclusion of the characteristic of disturbance trajectory is obtained: in the case of serious disturbance degree, The "double peak" characteristic will appear in the active power fluctuation trajectory of tie-line, which is determined by the functional relationship between the active power of tie-line and the angle and voltage of the tie-line. In this paper, a DC stability control strategy based on the characteristics of tie-line disturbance trajectory is proposed. When the stability margin of the system decreases seriously and the "double peak trajectory" occurs, the DC emergency control can be initiated at the first peak value. When the stability margin of the second peak system is significantly increased, the DC emergency control is withdrawn and the control effect of the control strategy is verified under different conditions. In order to weaken the influence of fault in Sichuan network on the inter-connection channel between Central China and North China, this paper analyzes the influence of power unit start-up mode on system stability in Sichuan Power Grid, classifies the thermal power unit according to its function, and gives the optimized startup mode. By changing the distribution of inertia, weakening the superposition of oscillation mode and enhancing the voltage support of power grid, the effect is verified. The effect of reducing load release power to reduce the impact of Sichuan network fault on UHV power grid.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM712

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