A grid interface for distributed energy resources with integrated energy storage using a high frequency AC link

A multiport converter with a high frequency (hf) ac bus is proposed for use as a distributed energy resource (DER) to grid interface with an integrated energy storage system (ESS). The combination of DER and ESS allows the DER to provide load following, load leveling, power quality compensation, voltage and frequency control, and spinning reserve, as well as savings on deferred installation of new transmission lines and centralized power plants, reduced loads on existing transmission lines, increased grid security and reliability, and the potential to adjust power delivery to take advantage of the energy market. The use of the hf-ac bus allows the boost and dc-hf ac conversion functions to be combined into a single converter and reduces the size of the transformer and passives. The proposed design allows independent control of each of the DER and ESS inputs, allowing for modular design and ease of expansion for the system. The digest explores several of the challenges of the design and presents theoretical and simulated waveforms for one of the operating conditions. Seven possible operating conditions are identified, and the applicability of each operating condition is determined when the system is used for power generation, load leveling, and spinning reserve.