Bailu Xiao

Development of hardware-in-the-loop microgrid testbed

A hardware-in-the-loop (HIL) microgrid testbed for the evaluation and assessment of microgrid operation and control system has been presented in this paper. The HIL testbed is composed of a real-time digital simulator (RTDS) for modeling of the microgrid, multiple NI CompactRIOs for device level control, a prototype microgrid energy management system (MicroEMS), and a relay protection system. The applied communication-assisted hybrid control system has been also discussed. Results of function testing of HIL controller, communication, and the relay protection system are presented to show the effectiveness of the proposed HIL microgrid testbed.

Advanced Energy Storage Management in Distribution Network

With increasing penetration of distributed generation (DG) in the distribution networks (DN), the secure and optimal operation of DN has become an important concern. In this paper, an iterative mixed integer quadratic constrained quadratic programming model to optimize the operation of a three phase unbalanced distribution system with high penetration of Photovoltaic (PV) panels, DG and energy storage (ES) is developed. The proposed model minimizes not only the operating cost, including fuel cost and purchasing cost, but also voltage deviations and power loss. The optimization model is based on the linearized sensitivity coefficients between state variables (e.g., node voltages) and control variables (e.g., real and reactive power injections of DG and ES). To avoid slow convergence when close to the optimum, a golden search method is introduced to control the step size and accelerate the convergence. The proposed algorithm is demonstrated on modified IEEE 13 nodes test feeders with multiple PV panels, DG and ES. Numerical simulation results validate the proposed algorithm. Various scenarios of system configuration are studied and some critical findings are concluded.

Community Microgrid Scheduling Considering Network Operational Constraints and Building Thermal Dynamics

This paper proposes a Mixed Integer Conic Programming (MICP) model for community microgrids considering the network operational constraints and building thermal dynamics. The proposed multi-objective optimization model optimizes not only the operating cost, including fuel cost, electricity purchasing/selling, storage degradation, voluntary load shedding and the cost associated with customer discomfort as a result of the room temperature deviation from the customer setting point, but also several performance indices, including voltage deviation, network power loss and power factor at the Point of Common Coupling (PCC). In particular, we integrate the detailed thermal dynamic model of buildings into the distribution optimal power flow (D-OPF) model for the optimal operation. Thus, the proposed model can directly schedule the heating, ventilation and air-conditioning (HVAC) systems of buildings intelligently so as to to reduce the electricity cost without compromising the comfort of customers. Results of numerical simulation validate the effectiveness of the proposed model and significant savings in electricity cost with network operational constraints satisfied.

A robust load shedding strategy for microgrid islanding transition

A microgrid is a group of interconnected loads and distributed energy resources. It can operate in either gridconnected mode to exchange energy with the main grid or run autonomously as an island in emergency mode. However, the transition of microgrid from grid-connected mode to islanded mode is usually associated with excessive load (or generation), which should be shed (or spilled). Under this condition, this paper proposes an robust load shedding strategy for microgrid islanding transition, which takes into account the uncertainties of renewable generation in the microgrid and guarantees the balance between load and generation after islanding. A robust optimization model is formulated to minimize the total operation cost, including fuel cost and penalty for load shedding. The proposed robust load shedding strategy works as a backup plan and updates at a prescribed interval. It assures a feasible operating point after islanding given the uncertainty of renewable generation. The proposed algorithm is demonstrated on a simulated microgrid consisting of a wind turbine, a PV panel, a battery, two distributed generators (DGs), a critical load and a interruptible load. Numerical simulation results validate the proposed algorithm.

Architecture and implementation of microgrid controller

A microgrid controller, the Complete System-level Efficient and Interoperable Solution for Microgrid Integrated Controls (CSEISMIC), is presented in this paper. The architecture and major components of the microgrid are introduced, followed by a discussion of the functions and implementation of the microgrid controller, including the Energy Management System (EMS) and Supervisory Control and Data Acquisition (SCADA). Testing results are provided to validate and demonstrate the effectiveness of the proposed microgrid controller.

Economic feasibility analysis and operational testing of a community energy storage system

A study of the impact of utility rates on the economic viability of Community Energy Storage (CES) is presented in this paper. Using the U.S. Utility Rate Database, the residential rate structures available at each available zip code in the continental United States were analyzed to see how viable CES is for that zip code. An operational CES hardware system was also tested to verify the results from economic analysis for the specific regions.

Software-defined intelligent grid research integration and development platform

A complication to control schemes is the fact that models can only represent the systems to the fidelity of the model. There is a need for hardware testing which can truly represent the dynamics of the system and the integration of the controls. A flexible and reconfigurable hardware low-power microgrid testbed platform is proposed in this paper for the verification of control schemes, protection and cyber-security. The design of multi-microgrid hardware configuration, shadow network architecture, and data collection and analytics are discussed.

Implementation of system level control and communications in a Hardware-in-the-Loop microgrid testbed

A Hardware-in-the-Loop (HIL) microgrid testbed for the evaluation and assessment of microgrid operation and control is presented in this paper. The HIL testbed is composed of a Real-Time Digital Simulator (RTDS) for modeling of the microgrid, multiple National Instruments (NI) CompactRIOs for Intelligent Electronic Device (IED) control, a prototype Energy Management System (EMS), and a Supervisory Control and Data Acquisition system (SCADA). The implementation of the system level control and communication is described, and testing results are presented to demonstrate the functionality of the proposed HIL microgrid testbed and microgrid controller.