A theoretical analysis on frequency stability of isolated hydropower plant with surge tank at HVDC sending terminal
Facing the challenge of hydropower curtailment in China, the West-East Electricity Transfer Project based on high-voltage direct current (HVDC) transmission systems is a key countermeasure.Operating stability of hydropower plants (HPPs) at HVDC sending terminals is an important guarantee, which needs further investigation, especially from a theoretical perspective.In this paper, the aim is to obtain a theoretical mathematical model and to analyze the frequency stability of isolated HPP with surge tank at HVDC sending terminal.The mathematical models for both theoretical analysis and time-domain simulation of the system are built, by applying MATLAB and Simulink.Xiao-wan HPP, which is within the Yun-Guang HVDC transmission system in China, is selected as the engineering case.In order to conduct the theoretical analysis, the Hurwitz stability criterion is applied, and a key point is the simplified treatment of boundary condition for the HVDC sending terminal.The focus of this paper is mainly on the influence from the hydraulic aspects, e.g.the governor parameters and the featured parameters regarding surge tank.The results show that the theoretical analysis and the time domain simulation achieve overall good agreement.The hydraulic instability of HPPs, especially the water level fluctuation in surge tanks, would lead to the ultra-low frequency oscillations of which the period is over 100 seconds, and it is obviously adverse for the frequency stability of the HVDC sending terminal.Importantly, the frequency (period) of the system oscillations caused by the poorly tuned governor parameters and the surge tank are different.It is suggested that the control parameter tuning should consider the factors from not only electrical side, but also hydraulic-mechanical aspects, for enhancing the stability of HVDC sending terminal.
Hydropower plant HVDC transmission Frequency stability Surge tank Theoretical analysis Time domain simulation
Weijia Yang Jiandong Yang Jiebin Yang
The State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan,430072, P.R.China
国际会议
法国巴黎
英文
26-32
2019-03-13（万方平台首次上网日期，不代表论文的发表时间）