Dynamic frequency control scheme for microgrids using energy storage
Aspects of the present disclosure describe methods and systems for improved control strategies for Dynamic Frequency Control (DFC) of Energy Storage (ES) devices which may be used to determine an amount of intertial support required from ES to provide frequency regulation based on type of disturbance and frequency control system of a microgrid. A case study showing the control strategy for DFC scheme is presented.
1. In a microgrid energy system comprising a one or more generation branches and one or more storage branches, each generation branch including an electrical generator and a local controller, each storage branch including an electrical storage unit and a local controller, the microgrid energy system having a central controller in communication with each of the plurality of local controllers, a computer implemented method for improved dynamic frequency control of the energy system said method comprising:
determining, by the central controller, basic information of the microgrid operation including configuration of each of the generators, parameters of each local controller and electrical topology;
determining, by the central controller, system resilience requirement including an accepted frequency deviation and maximum tolerable power disturbance;
updating, by the central controller, during operation of the energy system system parameters at a predetermined frequency;
developing, by the central controller, a reduced order model (ROM) of the system;
determining, by the central controller, a value of a virtual inertia of a branch from a state space model of the system derived from the ROM; and
providing, by the central controller, the virtual inertia value to the local controller of the branch for which the virtual inertia value was determined;
such that the one or more storage branches emulate the behavior of traditional synchronous generators thereby providing inertial support to the microgrid.
2. The method of claim 1 wherein the value of the virtual inertia is determined such that a maximum deviation of the frequency under a maximum tolerable power disturbance is smaller than an accepted frequency derivation.
3. The method of claim 2 wherein at least one of the plurality of generation branches is a renewable energy branch.