ANCILLARY SUPPORT THROUGH VIRTUAL SYNCHRONOUS GENERATOR AND ITS PERFORMANCE INVESTIGATION

Abstract

Over the last century, electrical energy infrastructures were predominantly driven by synchronous generators, supplying electricity to the majority of the global population. Further, the electrical system was originally designed with a core of centralized power plants responsible for generating the required energy to meet the needs of end-users, and with a well-defined power flow, divided primarily into transmission and distribution networks, as well as a range of consumers connected at various levels. However, the landscape of power systems has undergone a significant transformation in recent decades. In the first two decades of this new millennium, the traditional centralized and hierarchical electrical networks have seen a substantial integration of distributed energy resources, particularly wind and solar power along with energy storage systems. This transformation has been made possible, in parts, by the evolution and advancement of power conversion and power electronics technology. The widespread installation of wind, solar farms and energy storage connected at medium voltage networks, along with the proliferation of small distributed energy resources connected through power converters in low voltage systems, is fundamentally altering the dynamics of energy generation, distribution, and consumption. Further, the integration of distributed energy resources, particularly those utilizing renewable energy sources, has also introduced several challenges for grid operators. These challenges stem from the inherent stochastic nature of energy production by such sources. Also, the challenges related to grid stability and the reliability of responses during grid contingencies are being imposed. In response to these challenges, adjustments are aimed at ensuring the continued smooth and secure operation of the electrical network. Power system operators have modified the grid codes to accommodate the newly integrated devices without affecting the security of the system. Also, in an effort to maintain the stability of system, ancillary support is availed through different distributed energy resources such as wind, solar power, demand side management, electric vehicle. These techniques have been discussed in this thesis and it has been noticed that, out of all ancillary support services, ensured frequency support services and inertia provision cannot be necessarily guaranteed by the above-mentioned different technologies. In order to overcome the limitations of these technologies, virtual synchronous generator is being utilised in present time. Thus, an overview related to virtual synchronous generator control strategy, its stability analysis techniques and energy storage sources incorporated in it, are discussed. In lieu of the advantages being by provided by virtual synchronous generator, there are still research gaps lying in its control design and its interaction with the system. This thesis contributes in overcoming these research gaps by proposing novel strategies that are discussed in different chapters