A Smart and Flexible Microgrid with a Low-cost Scalable Open-source Controller
This project will develop a new type of microgrid with its corresponding controller. Like most other microgrids, the proposed microgrid will have solar PV based distributed generation and is capable of grid-connected and islanded operations; unlike them, which usually feature one single utility interface point and fixed boundaries, the proposed microgrid will incorporate the smart grid capabilities including multiple utility feeds, intelligent switches and ultra-high speed communication links. The microgrid controller will accommodate and utilize these smart grid features that already or will exist in many US utilities, for enhanced performance and reduced cost. The controller will be open source, based on the general-purpose hardware and software platform, offering a flexible, robust and secure development and implementation environment. The microgrid and its controller design will also be scalable for different geographic areas, load sizes, distributed generation source number and types, and even multiple microgrids within a utility area electric power system.
Conceptual microgrid system
The proposed microgrid is expected to improve the energy use efficiency by 20% and reduce the annual critical loads interruption time by 98% from 50 minutes to 1 minute. At the same time, the controller and its deployment cost can be cut by half. The community based microgrid and its controller will help the proliferation of the microgrid technology, which can lead to 1% reduction of the total CO2 emission by electricity generation in US if widely used.
There are two main phases for the project, the design phase and the testing phase. The design phase will focus on the MG design, implementation, and design methodology development, as well as the MG controller development. The testing phase will focus on testing the designed and developed MG and MG controller using multiple simulation and emulation platforms, as well as the controlled field testing. During the testing phase, technology to market activities will be conducted on commercialization of the developed open source low cost MG controller.
How WBG Can Help
The WBG based power electronics equipment will benefit microgrid operation performance. In addition to reduced loss and high power density, the high voltage rating of SiC devices can simplify converter topology by eliminating the necessity of multilevel structure or series connection of devices.
The high switching frequency capability of WBG devices enables microgrid components (e.g., converters of energy storage system, PV, wind turbine, etc.) to improve power quality, especially when nonlinear loads are served, without extra active power filter or passive filters. Moreover, the high switching frequency operation will also help damping the oscillation induced by step power change (e.g., sudden load swing) in a microgrid system through fast power deficit compensation.
Stability caused by connecting multiple converters is another potential issue in microgrid. Limited by relatively low control bandwidth, the Si based converters cannot behave like ideal voltage and/or current sources, which may lead to instability and bring disastrous damage to microgrid. Fortunately, by employing WBG devices, the control bandwidth can be greatly increased, thus enhancing system stability.
- Xiaojie Shi