A High Fault Current Synchronous Condenser for Support of Renewable Grids

With an increasing share of renewable energy sources being connected to electrical power networks, transient energy from the rotating inertia of traditional power plant is reducing. Renewable energy resources are highly dynamic and somewhat intermittent compared to more traditional generation sources. Hence, they pose a challenge to the electrical network operator in terms of effectively managing their resources to maximize energy transfer while maintaining stable operation. Existing renewable generation normally has low transient energy, which reduces system inertia. This increases the specification requirements of other interconnected components. Specifically, the physical characteristics of power electronics limits the output current of renewable schemes during fault. The paper will initially discuss the operational concept of a synchronous condenser with reference to the support of renewable and localized embedded generation. An example synchronous condenser design is presented to illustrate the provision of some limited energy input during energy transients, some reactive VAR capability, but importantly, supply of high transient fault currents. The paper discusses the synchronous condenser electromagnetic design in terms of machine impedance to realize high fault levels. A low power synchronous machine is studied to illustrate design considerations.