A Multi-Processor Control System Architecture for a Cascaded StatCom with Energy Storage

This paper presents a multi-processor control system for a general purpose five-level cascaded inverter for real time power system applications. Practical design considerations for the digital controller architecture as well as the power converter are discussed and a 3 kVA laboratory prototype is presented. As a case study, a StatCom with battery energy storage was implemented on this multi-processor controlled inverter system. To eliminate the troublesome PI parameter tuning and the limitation of small signal models, which exist in conventional control for StatComs, a new and simple control method based on large signal model was designed to realize four-quadrant power injections into a grid. Experimental results are provided to support the proposed concept

A Novel Real-time Approach to Unified Power Flow Controller Validation

This paper presents the development of a real-time hardware/software laboratory to interface a soft real-time power system simulator with multiple unified power flow controllers (UPFC) via hardware-in-the-loop (HIL) to study their dynamic responses and validate control and placement approaches. This paper describes a unique laboratory facility that enables large-scale, soft real-time power system simulation coupled with the true physical behavior of a UPFC as opposed to the controller response captured by many other real-time simulators. The HIL line includes a synchronous machine, a UPFC, and a programmable load to reproduce the physical dynamics of the UPFC sub-network

A Comparison of FACTS Integrated with Battery Energy Storage Systems

The integration of energy storage into FACTS devices lead to increased controller flexibility by providing decentralized active power capabilities. Combined FACTS/ESS can improve power flow control, oscillation damping and voltage control. This paper presents a comparison between the dynamic performance of a StatCom, a StatCom/BESS, an SSSC, an SSSC/BESS and a UPFC. Experimental verification is also presented

Control of STATCOM with Energy Storage Device

In this paper, the control method of a STATCOM with an energy storage device is discussed. To determine the switching level control, UPWM (unique pulse width modulation) and SPWM (sinusoidal pulse width modulation) methods are compared. A linearized model of a STATCOM with a battery is set up to derive monitoring level control strategies. All the control methods are verified by the PSCAD/EMTDC software package

A Comparison of Diode-Clamped and Cascaded Multilevel Converters for a STATCOM with Energy Storage

The progression of distributed generation within a bulk power system will lead to the need for greater control of transmission-line power flows. Static synchronous compensators (STATCOMs) provide a power-electronics-based means of embedded control of transmission-line voltage and power flows. The integration of energy storage with a STATCOM can extend traditional STATCOM capabilities to four-quadrant power flow control and transient stability improvement. This paper discusses energy storage systems (ESSs) integrated with conventional and multilevel bidirectional power converters for a hybrid STATCOM/ESS. Conventional, diode-clamped, and cascaded multilevel converter-based STATCOM/ESSs are developed, and their performances for a variety of power system applications are compared using battery energy storage. The advantages and disadvantages of each topology are presented. Both simulation and experimental results are provided to validate the conclusions

Integration of a StatCom and Battery Energy Storage

The integration of an energy storage system, such as battery energy storage (BESS), into a FACTS device can provide dynamic decentralized active power capabilities and much needed flexibility for mitigating transmission level power flow problems. This paper introduces an integrated StatCom/BESS for the improvement of dynamic and transient stability and transmission capability; compare the performance of the different FACTS/BESS combinations, and provide experimental verification of the proposed controls on a scaled StatCom/BESS syste

A Novel Approach to Interarea Oscillation Damping by Unified Power Flow Controllers Utilizing Ultracapacitors

This paper discusses a novel approach for damping interarea oscillations in a bulk power network using multiple unified power flow controllers (UPFCs) utilizing ultracapacitors, also known more generally as electrochemical capacitors (ECs). In this paper, a new control is introduced to mitigate interarea oscillations by directly controlling the UPFCs\u27 sending and receiving bus voltages that better utilizes the stored energy in the ECs. The results of this controller are compared with and without ECs. The proposed control provides better interarea oscillation mitigation when applied to multiple UPFCs in the 118-bus IEEE test system

A Reconfigurable FACTS System for University Laboratories

To fully understand the dynamic performance of the multiple flexible ac transmission systems (FACTS) devices, a hardware setup is needed to complement software simulation for university research laboratories. This paper presents the schematic and basic controls of a reconfigurable FACTS system that can be used to realize the major voltage-sourced-converter FACTS topologies: the StatCom, the static synchronous series compensator (SSSC), and the unified power-flow controller (UPFC). Furthermore, the state models and control algorithms for the FACTS devices are proposed. The digital signal processor (DSP)-based control system enables new control methods to be rapidly implemented. The comparison of the experimental and simulation results is also provided to verify the proposed controls. The paper culminates in a list of suggested experiments appropriate for an elective/graduate course in electric power systems

A Comparison of the Dynamic Performance of FACTS with Energy Storage to a Unified Power Flow Controller

The integration of an energy storage system into FACTS devices may lead to a more economical and/or flexible transmission controller. Various energy storage systems have received considerable attention in power utility applications due to their characteristics that range from rapid response, high power, high efficiency, and four-quadrant control. The enhanced performance of combined FACTS/ESS may have greater appeal to transmission service providers. Integrating an energy storage system into a FACTS device can provide dynamic decentralized active power capabilities and much needed flexibility for mitigating transmission level power flow problems. This paper presents a comprehensive comparison between the dynamic performances of a StatCom, a StatComBESS, an SSSC, an SSSC/ESS and a UPFC

Linear Single Phase Inverter Model for Battery Energy Storage System Evaluation and Controller Design

A method for deriving a set of linear transfer functions for a single phase grid tied system is presented, which can be used to determine how small signal perturbations and transients on the utility side are translated through the inverter to the dc link, as well as assist in controller design. These transfer functions can be used by a Battery Energy Storage System (BESS) designer to predict what harmonics the battery will see in the field, without the need for expensive simulation software. With this information, battery designers will be able to design a more robust battery specifically tailored for single phase inverter applications