Control method and system for improving power network stability
AssigneeLuxembourg Institute of Science and Technology (List)
InventorsPedro RODRIGUEZ CORTES, Nicholas Gregory BALTAS
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Abstract
A control method and system is provided for power converters that are electrically interconnected through a power grid. The control mechanism uses a digital model of a mechanical shaft for emulating the electrical coupling between each pair of power converters. Power transfers computed using this multi-shaft model are applied at the corresponding power converters, which results in stable and disturbance-resilient power signals throughout the power network.
Claims14
A control method for improving supply stability in a power network that electrically connects a first power converter to at least one second power converter through a power grid, the method comprising the steps of:
- i) providing, for each pair of power converters composed of the first power converter and one of the second power converters, a digital shaft model of a mechanical shaft in a memory element, wherein said digital shaft model comprises a damping factor, an inertia and a stiffness of a mechanical shaft and emulates the electrical coupling between said pair of power converters through said power grid;
- ii) obtaining, at a control unit, a pair of input signals from each of said pairs of power converters, wherein the input signals of a pair are indicative of rotating speeds applied to the ends of the corresponding digital shaft model;
- iii) determining an active power deviation at the control unit, based on power transfers that are computed for each pair of power converters by applying a rotation equation to the corresponding digital shaft model using the corresponding pair of input signals;
- and
- iv) at the control unit, communicating a reference signal to the first power converter, which allows the first power converter to feed the active power deviation into the power grid or to absorb the active power deviation from the power grid, depending on the positivity of the active power deviation.
A control unit comprising:
- a memory element in which digital shaft models are stored, each digital shaft model comprising a damping factor, an inertia and a stiffness of a mechanical shaft configured to emulate the electrical coupling between pairs of power converters electrically connected through a power grid, wherein each pair of power converters is composed of the same first power converter and one second power converter;
- receiving means configured to receive a pair of input signals from each of said pairs of power converters, wherein the input signals of a pair are indicative of rotating speeds applied to the ends of the corresponding digital shaft model;
- computing means configured to
- determine an active power deviation, based on power transfers that are computed for each pair of power converters by applying a rotation equation to the corresponding digital shaft model using a corresponding obtained pair of input signals;
- generate a reference signal, which allows the first power converter to feed the determined active power deviation into the power grid or to absorb the determined active power deviation from the power grid, depending on the positivity of the determined active power deviation;
- transmission means configured to communicate said reference signal to the first power converter.
Dependencies are inferred from the claim text.