Transient Stability Analysis And Regional Cooperative Control Of PV/HESS Interconnected Power System With Controlled Inertia

Expanding inertia from hybrid energy storage device(HESD)can improve the frequency stability of system with high penetration of photovoltaic power generetors effectively.However,the transient stability of system will be affected by complex inertia adjustment.Unreasonable inertia distribution has a negative effect on the system damping and power angle oscillation.Even the effect of inertia in different regions on damping characteristics of the system is opposite.In order to achieve transient stability improvement,this paper analyzes the transient stability mechanism of the interconnected power system with contrlloed inertia.The main research results are listed as follows:(1)Firstly,the conversion relationships between the stored energy in battery and capacitor,and the mechanical kinetic energy of synchronous generator are established.Subsequently,the virtual inertia hidden in HESD is obtained for the frequency-coupled capability.The small disturbance model of a power system with virtual inertia is derived,and the impact of frequency-coupled HESD on frequency stability and damping characteristics is analyzed by observing the variation of the system characteristic root with the virtual inertia coefficient.(2)Secondly,the virtual synchronous coupling control technology of HES D with variable inertia is proposed based on transient stability mechanism analysis.Therefore,HESD can transfer the transient energy of synchronous generato r in a more flexible mode,reduce system frequency and power angle oscillation.(3)Thirdly,the equivalent model of PV/HESD interconnected system is derived and the effect of virtual inertia on power angle’s first swing was analyzed.Then,the effect of adjustable virtual inertia on the damping characteristic is analyzed by establishing the small-signal model and using eigenvalue analysis method.Besides,a regional cooperative control of PV/HESD interconnected power system is proposed.The virtual inertia control coefficients of di fferent regions are reasonably configured to improve the damping characteristics of the system.(4)Finally,a high permeability test system with photovoltaic and HESD is built on MATLAB/Simulink in order to verify the correctness and effectiveness of the proposed strategy.The results show that the transient stability characteristics including frequency,power angle and damping can be significantly improved.