摘要
虚拟同步发电机(VSG)控制策略的复杂性使其呈现丰富的暂态特征,明确VSG故障特性对构网型保护适应性分析与新原理研究意义重大。现有关于VSG故障特性的研究主要围绕对称短路和内电势恒定展开,并未涉及不对称短路场景且未计及内电势变化对短路电流解析计算的影响。针对上述问题,提出一种计及内电势变化影响的VSG不对称短路暂态电流解析计算方法。首先,基于不对称短路时平衡电流和故障限流控制策略,分析不同无功功率参考值影响下VSG内电势的变化特征;其次,基于虚拟阻抗环建立短路电流和内电势之间的方程,明晰内电势变化对短路电流暂态特性的影响;然后,在分析无功功率-电压环动态特性的基础上,建立短路电流和内电势之间的微分方程,通过联立上述方程即可得到内电势和短路电流的解析表达式;最后,通过数字仿真和实时仿真验证了所推导的解析计算式的正确性。
The complexity of the control strategy of the virtual synchronous generator(VSG)makes it present rich transient characteristics.Clarifying the fault characteristics of VSG is of great significance for the adaptability analysis and the new principle study of grid-forming protection.Existing studies on VSG fault characteristics mainly focus on symmetric short circuit and constant internal potential,but do not involve asymmetric short-circuit scenarios and do not take into account the effect of internal potential change on the analytical calculation of the short-circuit current.To address the above problems,this paper proposes a transient current analytic calculation method for the VSG with asymmetric short circuit considering the influence of the internal potential change.Firstly,based on the balancing current and fault current limiting control strategy during the asymmetric short circuit,the characteristics of the internal potential of VSG under the influence of different reactive power reference values are analyzed.Secondly,the equation between the short-circuit current and the internal potential is established based on the virtual impedance loop so as to clarify the influence of the internal potential change on the transient characteristics of the short-circuit current.Then,the differential equations between the short-circuit current and the internal potential are established based on the analysis of the dynamic characteristics of the reactive power-voltage loop.Thirdly,the analytical expressions of the internal potential and the shortcircuit current can be obtained by associating the above equations.Finally,the correctness of the derived analytical formula is verified by digital simulation and real-time simulation.
作者
郑涛
马英
陈云飞
孟令昆
ZHENG Tao;MA Ying;CHEN Yunfei;MENG Lingkun(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Beijing 102206,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2024年第19期162-170,共9页
Automation of Electric Power Systems
基金
国家自然科学基金联合基金资助项目(U2166205)。
关键词
虚拟同步发电机
内电势
暂态电流
低电压穿越
无功功率支撑
平衡电流控制
不对称短路
virtual synchronous generator(VSG)
internal potential
transient current
low voltage ride-through
reactive power support
balancing current control
asymmetric short circuit
