构网型无功补偿抑制新能源送端暂态过电压

Suppression of transient overvoltage in renewable energy transmission terminal by grid-forming based reactive power compensation

电网换相换流器型高压直流输电(line commutated converter based high voltage direct current,LCC-HVDC)是新能源大规模并网、远距离外送的关键。而直流闭锁、换相失败等故障可能导致送端短时无功过剩并引发暂态过电压,危及运行安全。文中突破传统基于电压-电流级联控制的电流源外特性快速无功补偿装置的技术原理,提出一种应用构网型无功补偿装置(grid-forming based reactive power compensation device,GFM-RPC)抑制新能源送端暂态过电压的方法,构建基于微分-代数关系的电压动态分析模型,阐明GFM-RPC抑制暂态过电压机理,并分析GFM-RPC相比现有基于静止同步补偿器(static synchronous compensator,STATCOM)抑制暂态过电压方法的优势。利用仿真验证GFM-RPC抑制新能源送端暂态过电压的效果,并分析主要参数对过电压抑制效果的影响。研究表明,STATCOM这类电流源外特性的无功补偿装置在直流输电系统故障瞬间呈现出恶化电压动态的“反调”特性,而GFM-RPC能够克服这种“反调”特性,并且通过合理的参数配置可以进一步抑制电压幅值的超调量。

Line commutated converter based high voltage direct current(LCC-HVDC)is the key to large-scale grid connection and long-distance transmission of renewable energy.However,faults such as DC blocking and commutation failure may lead to short-term excess reactive power and transient overvoltage at the sending end,endangering operational safety.In this paper,a method based on grid-forming based reactive power compensation device(GFM-RPC)to suppress transient overvoltage at the renewable energy transmission terminal is proposed,which is different from the traditional reactive power compensation with the characteristic of current source based on voltage-current cascade control.A voltage dynamic analysis model based on differential-algebraic relationship is constructed to clarify the mechanism of GFM-RPC suppressing transient overvoltage,and the advantages of the proposed method compared to existing methods based on static synchronous compensator(STATCOM)for suppressing transient overvoltage is compared and analyzed.The simulation is used to verify the effect of GFM-RPC on the suppression of transient overvoltage at the renewable energy transmission terminal,and the influence of the main parameters on the overvoltage suppression effect is analyzed.It is shown that reactive power compensation devices such as STATCOM with external characteristics of current sources exhibit a reverse regulation characteristic of deteriorating voltage dynamics at the moment of DC transmission system fault,while the reverse regulation characteristic can be eliminated by GFM-RPC,as well as suppression of voltage magnitude overshoot can be achieved through reasonable parameter configuration for GFM-RPC.