Power Quality and compensation

2005-2006

1) Project Title: Multifunctional Compensation Strategies for Distributed Active Compensator Systems
Investigator: Herb Ginn

Objectives: Active Compensators are given many different names depending on the application, however, they are all applied as active compensators by injecting current into the system at the cross section where they are connected. The term “Active Compensator” is used here because it either compensates for unwanted current components or the lack of desired current components. There are many control strategies for active compensators suggested in the literature. Despite the great number of different control strategies suggested for these compensators, nearly all use similar methods for generation of the current reference signal. These methods generally depend upon the use of filters to extract reference signals for the components that are to be compensated. In this way the compensator’s behavior is tailored by the selection of filter parameters and the selection of components to be filtered. This method of compensator control design is not flexible. Once the filter types and parameters have been set, the behavior of the compensator is fixed. Furthermore, very little research has been conducted in the area of systems of multiple compensators.

This objective of this research topic is to develop the control architecture of active compensators such that maximum flexibility of the compensators’ possible functions is achieved and to enable coordinated operation of distributed compensators. This will consist of several aspects, including research into appropriate control algorithms and their partitioning, modeling and simulation, and finally development of a test-bed consisting of interconnected compensators in order to validate the developed approach on a system level.

2) Project Title: Pulsed Load Compensation Strategies for Shunt Active Compensators
Investigators: Herb Ginn, David Gao

Objectives: The degree of active and reactive power variation due to pulsed loading may affect the quality and stability of the distribution system. Pulsed loads would not usually be connected directly to the distribution system, however, the energy storage units that supply them will be charged from the distribution system. Such energy storage systems may represent large power loads with supply current magnitudes that vary over a wide range affecting the supply voltage. The effects of pulsed loads should be compensated for, otherwise unacceptable voltage fluctuation and distortion may occur during pulsed loading.

The function of an active compensator may be expanded to include pulsed load compensation. The capacity of the energy storage and the energy storage medium incorporated into the compensator determine the available types of compensation that can be performed. Thus, an Active Compensator can be employed for harmonic suppression, reactive power compensation and pulsed load compensation depending on the amount of energy storage available to the compensator.

Unlike compensators used solely for harmonic distortion or reactive power compensation, the variation of load active power requires a substantial amount of energy storage. Although researchers are in agreement as to the need for energy storage, it has not been quantified. Therefore, it is anticipated that the most difficult type of compensation from the standpoint of the control system is that required by pulse type loads. Investigation of energy storage requirements for pulsed load applications and the inclusion of these requirements in the control architecture and partitioning are necessary. The main objective of the proposed research topic is the investigation of energy storage requirements for pulsed loads and the inclusion of these requirements in the control architecture and partitioning of active compensator systems.

2006-2007

1) Project Title: Distributed Multifunctional Shunt Current Controller System
Investigator: Herbert L. Ginn

Objective: Flexible management of energy flow throughout shipboard distribution systems by means of multi-functional power electronic converter systems is highly desirable. Here the focus is restricted to the Shunt Current Controller (ShCC) class of applications. The objective of this research is to refine the development of the control architecture of ShCCs such that maximum on-line flexibility of their possible functions is achieved and to enable coordinated operation of distributed systems of ShCCs.