Driven by rising energy demand and the goal of carbon neutrality, renewable energy generations (REGs), especially photovoltaic (PV) generations, are widely used in the urban power energy systems. While the intelligent control of microgrids (MG) brings economic and efficient operation, its potential stability problem cannot be ignored. To date, most of the research on modeling, analyzing and enhancing the stability of MG usually assume the DC-link as an ideal voltage source. However, this practice of ignoring the dynamics of DC-link may omit the latent oscillation phenomena of autonomous PV-based MG. First, this paper establishes a complete dynamic model of autonomous PV-based MG including PV panels and DC-link. Different from previous conclusions of idealizing DC-link dynamics, participation factor analysis finds the potential impact of DC-link dynamics on system dynamic performance, and different influence factors including critical control parameters and non-linear $V$- $I$ output characteristic of PV array are considered to further reveal oscillation mechanisms. Second, based on the average consensus algorithm, a distributed stabilization controller with strong robustness is proposed to enhance stability of the PV-based MG, which does not affect the steady-state performance of the system. Finally, the correctness of all theoretical analysis and the effectiveness of the proposed controller are verified by time domain simulation and hardware-in-loop tests.

As extreme weather events have become more frequent in recent years, improving the resilience and reliability of power systems has become an important area of concern. In this paper, a robust preventive-corrective security-constrained optimal power flow (RO-PCSCOPF) model is proposed to improve power system reliability under N-k outages. Both the short-term emergency limit (STL) and the long-term operating limit (LTL) of the post-contingency power flow on the branch are considered. Compared with the existing robust corrective SCOPF model that only considers STL or LTL, the proposed RO-PCSCOPF model can achieve a more reliable generation dispatch solution. In addition, this paper also summarizes and compares the solution methods for solving the N-k SCOPF problem. The computational efficiency of the classical Benders decomposition (BD) method, robust optimization (RO) method, and line outage distribution factor (LODF) method are investigated on the IEEE 24-bus Reliability Test System and 118-bus system. Simulation results show that the BD method has the worst computation performance. The RO method and the LODF method have comparable performance. However, the LODF method can only be used for the preventive SCOPF and not for the corrective SCOPF. The RO method can be used for both.