The ever increasing progress of high-voltage high-power fully controlled semiconductor technology continues to have a significant impact on the development of advanced power electronic apparatus used to support optimized operations and efficient management of electrical grids, which, in many cases, are fully or partially deregulated networks. Developments advance both the HVDC power transmission and the flexible ac transmission system technologies. In this paper, an overview of the recent advances in the area of voltage-source converter (VSC) HVdc technology is provided. Selected key multilevel converter topologies are presented. Control and modeling methods are discussed. A list of VSC-based HVdc installations worldwide is included. It is confirmed that the continuous development of power electronics presents cost-effective opportunities for the utilities to exploit, and HVdc remains a key technology. In particular, VSC-HVdc can address not only conventional network issues such as bulk power transmission, asynchronous network interconnections, back-to-back ac system linking, and voltage/stability support to mention a few, but also niche markets such as the integration of large-scale renewable energy sources with the grid and most recently large onshore/offshore wind farms.

VSC-Based HVDC Power Transmission Systems: An Overview

(1990). ENERGY FUNCTION ANALYSIS FOR POWER SYSTEM STABILITY. Electric Machines & Power Systems: Vol. 18, No. 2, pp. 209-210.

Energy function analysis for power system stability

1. Introduction. 1.1 Background. 1.2 Electrical Transmission Networks. 1.3 Conventional Control Mechanisms. 1.4 Flexible ac Transmission Systems (FACTS). 1.5 Emerging Transmission Networks. 2. Reactor--Power Control in Electrical Power Transmission Systems. 2.1 Reacrive Power. 2.2 Uncompensated Transmission Lines. 2.3 Passive Compensation. 2.4 Summary. 3. Principles of Conventional Reactive--Power Compensators. 3.1 Introduction. 3.2 Synchronous Condensers. 3.3 The Saturated Reactor (SR). 3.4 The Thyristor--Controlled Reactor (TCR). 3.5 The Thyristor--Controlled Transformer (TCT). 3.6 The Fixed Capacitor--Thyristor--Controlled Reactor (FC--TCR). 3.7 The Mechanically Switched Capacitor--Thristor--Controlled Reactor (MSC--TCR). 3.8 The Thyristor--Switched capacitor and Reactor. 3.9 The Thyristor--Switched capacitor--Thyristor--Controlled Reactor (TSC--TCR). 3.10 A Comparison of Different SVCs. 3.11 Summary. 4. SVC Control Components and Models. 4.1 Introduction 4.2 Measurement Systems. 4.3 The Voltage Regulator. 4.4 Gate--Pulse Generation. 4.5 The Synchronizing System. 4.6 Additional Control and Protection Functions. 4.7 Modeling of SVC for Power--System Studies. 4.8 Summary. 5. Conceepts of SVC Voltage Control. 5.1 Introduction 5.2 Voltage Control. 5.3 Effect of Network Resonances on the Controller Response. 5.4 The 2nd Harmonic Interaction Between the SVC and ac Network. 5.5 Application of the SVC to Series--Compensated ac Systems. 5.6 3rd Harmonic Distortion. 5.7 Voltage--Controlled Design Studies. 5.8 Summary. 6. Applications. 6.1 Introduction. 6.2 Increase in Steady--State Power--Transfer Capacity. 6.3 Enhancement of Transient Stability. 6.4 Augmentation of Power--System Damping. 6.5 SVC Mitigation of Subsychronous Resonance (SSR). 6.6 Prevention of Voltage Instability. 6.7 Improvement of HVDC Link Performance. 6.8 Summary. 7. The Thyristor--Controlled SeriesCapacitor (TCSC). 7.1 Series Compensation. 7.2 The TCSC Controller. 7.3 Operation of the TCSC. 7.4 The TSSC. 7.5 Analysis of the TCSC. 7.6 Capability Characteristics. 7.7 Harmonic Performance. 7.8 Losses. 7.9 Response of the TCSC. 7.10 Modeling of the TCSC. 7.11 Summary. 8. TCSC Applications. 8.1 Introduction. 8.2 Open--Loop Control. 8.3 Closed--Loop Control. 8.4 Improvement of the System--Stability Limit. 8.5 Enhancement of System Damping. 8.6 Subsynchronous Resonanace (SSR) Mitigation. 8.7 Voltage--Collapse Prevention. 8.8 TCSC Installations. 8.9 Summary. 9. Coordination of FACTS Controllers. 9.1 Introduction 9.2 Controller Interactions. 9.3 SVC--SVC Interaction. 9.4 SVC--HVDC Interaction. 9.5 SVC--TCSC Interaction. 9.6 TCSC--TCSC Interaction. 9.7 Performance Criteria for Damping--Controller Design. 9.8 Coordination of Multiple Controllers Using Linear--Control Techniques. 9.9 Coordination of Multiple Controllers using Nonlinear--Control Techniques. 9.10 Summary. 10. Emerging FACTS Controllers. 10.1 Introduction. 10.2 The STATCOM. 10.3 THE SSSC. 10.4 The UPFC. 10.5 Comparative Evaluation of Different FACTS Controllers. 10.6 Future Direction of FACTS Technology. 10.7 Summary. Appendix A. Design of an SVC Voltage Regulator. A.1 Study System. A.2 Method of System Gain. A.3 Elgen Value Analysis. A.4 Simulator Studies. A.5 A Comparison of Physical Simulator results With Analytical and Digital Simulator Results Using Linearized Models. Appendix B. Transient--Stability Enhancement in a Midpoint SVC--Compensated SMIB System. Appendix C. Approximate Multimodal decomposition Method for the Design of FACTS Controllers. C.1 Introduction. C.2 Modal Analysis of the ith Swing Mode, C.3 Implications of Different Transfer Functions. C.4 Design of the Damping Controller. Appendix D. FACTS Terms and Definitions. Index.

Thyristor-Based Facts Controllers for Electrical Transmission Systems

In this paper, the principle of modularity is used to derive the different multilevel voltage and current source converter topologies. The paper is primarily focused on high-power applications and specifically on high-voltage dc systems. The derived converter cells are treated as building blocks and are contributing to the modularity of the system. By combining the different building blocks, i.e., the converter cells, a variety of voltage and current source modular multilevel converter topologies are derived and thoroughly discussed. Furthermore, by applying the modularity principle at the system level, various types of high-power converters are introduced. The modularity of the multilevel converters is studied in depth, and the challenges as well as the opportunities for high-power applications are illustrated.

Modular Multilevel Converters for HVDC Applications: Review on Converter Cells and Functionalities

This paper describes a new power system stabilizer (PSS) design for damping power system oscillations focusing on interarea modes. The input to the PSS consists of two signals. The first signal is mainly to damp the local mode in the area where PSS is located using the generator rotor speed as an input signal. The second is an additional global signal for damping interarea modes. Two global signals are suggested; the tie-line active power and speed difference signals. The choice of PSS location, input signals and tuning is based on modal analysis and frequency response information. These two signals can also be used to enhance damping of interarea modes using SVC located in the middle of the transmission circuit connecting the two oscillating groups. The effectiveness and robustness of the new design are tested on a 19-generator system having characteristics and structure similar to the Western North American grid.

Damping controller design for power system oscillations using global signals

This paper presents a coordinated control of a STATCOM and a Power System Stabilizer (PSS) for damping the low frequency electromechanical oscillations in a single machine infinite bus (SMIB) system. A model is developed which is subsequently linearized to form a state space model. The STATCOM control is based on modulation index and the phase angle control through pulse width modulation (PWM) technique. The controller parameters both for STATCOM and PSS are optimized using particle swarm optimization (PSO) algorithm using an eigenvalue based objective function. The optimized gains are then used in non-linear simulations developed in MATLAB to demonstrate the effectiveness of different control methodologies.

Coordinated control of STATCOM and PSS for damping generator electromechanical oscillations

This paper describes indigenous design, development, and commissioning of Remote Terminal Units (RTUs) for computer-aided monitoring and control of 10MVA power distribution network of Indian Institute of Technology Kanpur in India. RTUs play a significant role in data monitoring and control of the power distribution network from a remote location. Remote monitoring and control of the distribution system is also called Distribution Automation (DA). The developed and commissioned RTUs are based on an architecture that eliminates the requirement of DC transducer stage. This significantly reduces the cost and size of the RTU and the effort required during installation and commissioning of the RTU. The developed RTUs support the industry standard open protocol "Distributed Network Protocol (DNP3.0)" for data communication.

Remote terminal units for distribution automation: development and commissioning experience

Large-scale integration of wind farms in transmission networks has led to several challenges; one of which is the need for increased transmission capacity to transport bulk amounts of wind power Series compensation is an established means of enhancing the power transfer capability of existing transmission lines and is being increasingly considered for integrating large wind power plants However, series-compensated transmission lines may cause subsynchronous resonance (SSR) in turbine-generators, which can lead to electrical instability at subsynchronous frequencies and potential turbine-generator shaft failures This chapter presents a thorough mathematical analysis of SSR in a double-cage induction generator (IG) based wind farm connected to a series-compensated transmission line and its mitigation The prediction of SSR is done for a wide range of wind farm sizes and series compensation levels through eigenvalue studies and equivalent circuit analysis Two types of STATCOM controllers are proposed and tested with an aggregated wind farm model In the proposed controller-I the DC voltage remains uncontrolled and only the angular difference between the STATCOM terminal and the Point of Common Coupling (PCC) bus voltage is controlled In controller-II, the DC link capacitor voltage is controlled by the phase angle difference between the STATCOM terminal and PCC bus voltage Both the modulation index and angle are controlled in this controller Studies are conducted for three different induction generators used in commercial wind farms Fault studies are also conducted at different locations

STATCOM Application for Mitigation of Subsynchronous Resonance in Wind Farms Connected to Series-Compensated Transmission Lines

This paper presents a Bibliography of Flexible AC Transmission Systems (FACTS) for the year 2001.

Bibliography of FACTS: 2001 - Part II IEEE Working Group Report

This paper gives a summary of one of the presentations proposed under the Panel Session on “FACTS Fundamentals” sponsored by the DC and FACTS Subcommittee. This paper presents a brief description and operating principles of the different Flexible AC Transmission System (FACTS) Controllers.

http://www.ieee-pes.org/presentations/td2014/td2014p-000665.pdf

Rajiv K. Varma

Papers

Coordinated control of STATCOM and PSS for damping generator electromechanical oscillations

Remote terminal units for distribution automation: development and commissioning experience

STATCOM Application for Mitigation of Subsynchronous Resonance in Wind Farms Connected to Series-Compensated Transmission Lines

Bibliography of FACTS: 2001 - Part II IEEE Working Group Report

Elements of FACTS Controllers