Abstract: A power transmission system can include a transformer and compensator circuit(s), each coupled between a node of the transformer and a ground connection. The compensator circuit(s) can each be configured to counteract a DC signal component of an AC signal at the transformer. The compensator circuit(s) can include a converter circuit having an AC side and a DC side and configured to convert a DC voltage on the DC side to an AC signal at the AC side. The compensator circuit(s) can include a DC link coupled to the DC side of the converter circuit. The compensator circuit(s) can include a controller configured to measure a DC signal component between the load and the ground; to determine, based at least in part on the DC signal component, a compensating signal configured to counteract the DC signal component; and to inject, by the converter circuit, the compensating signal to counteract the DC signal component.

Abstract: An energy storage system controller, including: an energy storage system coupled to a power distribution system; and a processor in communication with the energy storage system, wherein the processor executes: a renewables capacity firming algorithm operable for conditioning intermittent power of a renewable energy station using real time and historical input data such that it is made more stable and non-intermittent, optionally utilizing one or more parameter values associated with comparable time periods taking into account one or more factors comprising cloud state; and a peak load shaving algorithm operable for ensuring that the energy storage system is capable of transmitting full power capacity at a predicted feeder peak load time determined by the processor from real time and historical input data; wherein the performance of the renewables capacity firming algorithm and the performance of the peak load shaving algorithm are optimized in parallel.

Abstract: A battery energy storage system control system, including: logic coupled to a photovoltaic station and an energy storage system and executing a photovoltaic station capacity firming algorithm operable for making a combined output of the photovoltaic station and the energy storage system substantially constant such that power swings on an associated feeder system are avoided; logic coupled to the photovoltaic station and the energy storage system and executing a voltage support algorithm operable for holding point of common coupling voltage and phase values substantially equal to substation voltage and phase values via power injection or removal; and logic coupled to the photovoltaic station and the energy storage system and executing an energy time shift algorithm operable for storing energy during periods of relatively low demand and providing energy during periods of relatively high demand.

Abstract: A variable speed, constant frequency (VSCF) system utilizes a doubly-fed machine (DFM) to maximize the output power of the system. The system includes a power converter that provides a frequency signal and a current signal to the DFM. The power converter is controlled by an adaptive controller. The controller signals the converter to vary its frequency signal and thereby the rotor speed of the DFM until a maximum power output is sensed. The controller also signals the converter to vary its current signal and thereby the portions of power carried by the respective windings until a maximum power output is sensed. The control can be augmented to not only maximize power and efficiency, but also provide for harmonic and reactive power compensation.