1. 1 PEBB-based Power Electronic Systems to Support MVDC Studies Herbert L. Ginn III, Mississippi State University

2. 2 One research focus area at MSU has been flexible management of energy flow throughout distribution systems by means of multi-functional power electronic converter systems. Multifunctional Power Electronic Converters Efforts in this direction have included: Investigation and development of PEBB based multi-functional converters by development of appropriate application level control architectures Development of lower level control functions to cope with shipboard power system concerns such as distorted voltages, high frequency variability, and EMI. Consideration of parallel operation and system level control issues of multiple power electronic converters Test-bed for experimental validation PEBB-based converter Digital controller Parallel converters

3. 3 Systems of Multifunctional Power Electronic Converters A current research focus area at MSU and USC is development of control methods that enable the coordinated operation of distributed systems of multi-functional power electronic converters. Some near term efforts of USC and MSU building on these capabilities that can support MVDC include: Development of a HIL interface for the MSU PEBB controller Further develop the MSU PEBB controller software so that it can be used as a real-time target for C code realizations of control algorithms generated using VTB Pro Combine the VTB based dynamic re- programming of the power modules and hardware-in-the-loop interface for the MSU controller in order to provide a test-bed for MVDC technologies This work leverages the multi-functional converter research conducted during the past two years at MSU as well as the research on mobile agents conducted at USC. PEBB and Load Test-bed at MSU.

4. 4 MSU PEBB Controller Ethernet communications capability and dual processor design are features of the new MSU controller board The new controller interfaces with the AMSC PM-1000 at the hardware control level PLANNED ENHANCEMENTS: Addition of a HIL interface to the reference signal generator VTB based code generation for fast control prototyping

5. 5 Phase I:CAPS PHIL experimental setup with AMSC PEBBs 4.16 kV utility bus 0-4.16 / 8.2 kV experimental bus 0-1.15 kV experimental DC bus DC Voltage reference from RTDS DC Current feedback to RTDS 0-480 V experimental bus, 1.5 MVA Bidirectional DC/DC Bidirectional DC/AC AMSC PEBB Based DC Zone Simulation Based Commands The HIL enabled PEBBs will be used to form a DC zone at the 100kW level in the CAPS test bed

6. 6 Present Experimental Setup for Agent Validation Converter 1 Load Bank Mini-dc linkConverter 2

7. 7 Phase II: HIL Experimental Setup with Active Rectifiers

8. 8 Power Systems Group: 1.Develop methodology for optimal power management based on steady state power flow models of DC system and controllers 2. Develop a method to implement simultaneous inter area de-coupling and local area oscillation damping in MVDC systems 3.Develop DC system fault detection and protection schemes 1.Cable testing with DC waveforms Other Proposed MVDC Activities at MSU High Voltage Group:

9. 9 Brief Description of The Proposed Activities Optimal Power Management Objective: To develop methods for optimal power management in MVDC systems. Motivation: Voltage source converters (VSCs) offer advantage in MVDC applications, with ease of parallel operation on DC side. VSCs can operate in voltage regulation mode or in power dispatch mode. Optimal settings of converters ensure desired power management and also avoid excessive voltage build up under failure of one of the converters. Approach: Use of steady state power flow models of MVDC system Optimal power flow methodology for the power management.

10. 10 System Stability and Control Objective: Develop a method for simultaneous inter area decoupling and local area damping in MVDC system and evolve control strategies to avoid excessive or low voltage build up under disturbances. Motivation: VSCs have two control degrees of freedom. Supplementary controllers need to be designed for inter area decoupling and local area damping. In addition, the converter controls have to be properly designed to avoid any excessive or low voltage build up under disturbances Approach: Develop dynamic model of MVDC system. Carry out transient and small signal stability studies. Design of controllers to damp out oscillations.

11. 11 MVDC System Protection Objective: To develop fault detection and protection schemes. Motivation: Detection of fault in MVDC system is relatively difficult. COTS protective devices not available. Proper protection schemes need to be developed to make the MVDC system reliable, dependable, and secure. Approach: Employing advance level converters. System modeling and transient simulation. Optimal control strategy of converters for protection under fault.

12. 12 Background Work Already Carried Out 1. MVDC system modeling employing 12-pulse converter rectifiers with static resistive load 2. MVDC protection study (in terms of fault propagation and system level impact) a)Impact of different converter configurations b)Impact of different converter control modes c)Impact of change in controller and system parameters 3. Ring bus MVDC system stability 4. Power quality issues including harmonics.