Adaptive VSG control strategy considering energy storage SOC constraints

The virtual synchronous generator (VSG) control strategy is proposed to mitigate the low inertia problem in the power system brought about by the high percentage of distributed generation connected to the grid and the application of power electronic devices. In order to maximize the effectiveness of the advantages of the flexible and adjustable parameters of VSG control, an adaptive VSG control strategy considering SOC constraint of the energy storage unit is proposed in this paper. Considering the significant loss of service life by operating the energy storage unit at its limit state, based on the rate and degree of change in system frequency, the adaptive control strategy realizes the online adaptive adjustment of the inertia factor and damping factor under different perturbation conditions by adaptively adjusting the control parameters when the system frequency oscillates. Finally, the effects of this adaptive VSG control method and conventional VSG control method are compared by simulation in PLECS. Hardware-in-the-loop (HIL) experimental platforms and semi-physical simulation experiments are constructed on RTBOX, and the feasibility and validity of this adaptive VSG control strategy are verified

Improving the Transient Stability of the Virtual Synchronous Generator

The majority of the Distributed Energy Resources (DERs), i.e., Energy Storage Systems (ESSs) and Renewable Energy Systems (RESs), utilize inverters to convert the Direct Current (DC) power to the Alternating Current (AC) power needed by the majority of the consumers. Proliferation of the inverter-based DERs has caused significant changes in the operation of the modern electric power systems. Inverters lack the mechanical inertia that is inherent in the traditional power generators, i.e., rotating electrical machines. As a result, the emerging inverter-dominated power systems suffer from lower stability margins, excessive frequency deviations, and poor dynamic response to disturbances. This issue has adversely affected the integration of the highly advantageous inverter-based renewable energy systems in microgrids and active distribution systems. Appropriate inverter control can be used to emulate virtual inertia by imitating the behavior of traditional generation units. Based on this idea, the concept of virtual synchronous generator (VSG) has been proposed. VSGs suffer from the transient stability issues that affect the operation of the Synchronous Generators (SGs). They can become unstable due to prolonged faults. Unlike the SGs that can handle significant over-current stress, VSGs have limited overcurrent capacity. The studies conducted in this research indicate that the current limiting strategy of the VSG significantly impacts its transient stability. The impacts of different inverter current limiting strategies on the performance of the VSG are investigated and the one that leads to the largest transient stability margin is identified

Annex III: Scenarios and modelling methods

The use of scenarios and modelling methods are pillars in IPCC Working Group III (WGIII) Assessment Reports. Past WGIII assessment report cycles identified knowledge gaps about the integration of modelling across scales and disciplines, mainly between global integrated assessment modelling methods and bottom-up modelling insights of mitigation responses. The need to improve the transparency of model assumptions and enhance the communication of scenario results was also recognised. This annex on Scenarios and Modelling Methods aims to address some of these gaps by detailing the modelling frameworks applied in the WGIII Sixth Assessment Report (AR6) chapters and disclose scenario assumptions and its key parameters. It has been explicitly included in the Scoping Meeting Report of the WGIII contribution to the AR6 and approved by the IPCC Panel at the 46th Session of the Panel