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Über dieses Buch

This book looks at the control of voltage source converter based high voltage direct current (VSC-HVDC). The objective is to understand the control structure of the VSC-HVDC system and establish the tuning criteria for the proportional-integral (PI) control of the converter controllers. Coverage includes modeling of the VSC-based HVDC transmission system using MATLAB and Simulink simulation package; implementation of control strategies for the VSC-based HVDC transmission system; and analysis of the developed system behavior under different conditions (normal and fault conditions). The book provides researchers, students, and engineers working in electrical power system transmission and power electronics and control in power transmission with a good understanding of the VSC-based HVDC transmission system concept and its behavior.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
The use of voltage source converter-based high-voltage direct current (VSC-HVDC) systems is considered to be a major step in facilitating long-distance power transfer and integrating remotely located renewable energy sources to major consumption centers. First introduced in 1997, with the commissioning of a 3 MW technology demonstrator in Sweden [1], VSC technology has improved drastically over the years in terms of power and voltage rating, harmonic performance, and losses [2, 3].
Nagwa F. Ibrahim, Sobhy S. Dessouky

Chapter 2. High-Voltage Direct Current Transmission

Abstract
The HVDC transmission is advantageous for power delivery over long distances and asynchronous interconnections by using overhead lines or underground cables. One of the most important aspects of HVDC systems is its fast and stable controllability [6]. Until recently, the classic HVDC transmission based on thyristors was used for power conversion from AC to DC and vice versa. The appearance of voltage source converter (VSC) makes use of more advanced semiconductor technology instead of thyristors. The VSC-based HVDC installations have several advantages compared to classic HVDC transmission such as independent control of active and reactive power and separate power systems interconnection. VSC-HVDC is also used to reverse the power flow direction without changing the polarity of DC voltage (in multiterminal DC systems), and there are no requirements of fast communication between the two converter stations [7].
Nagwa F. Ibrahim, Sobhy S. Dessouky

Chapter 3. VSC-HVDC Control System

Abstract
In the case of VSC-based HVDC transmission systems, the transfer of power is controlled in the same way as in the case of a classic HVDC transmission. The inverter side controls the active power, while the rectifier side controls the DC voltage [33, 56]. With classic HVDC, the reactive power cannot be controlled independently of the active power. VSC-HVDC makes it possible to control the reactive power and the active power independently. The reactive power flow can be controlled separately in each converter by the AC voltage that is requested or set manually without changing the DC voltage. The active power flow can be controlled by DC voltage on the DC side or the variation of frequency of AC side or set manually. Thus, the active power flow, the reactive power flow, the AC voltage, the DC voltage, and the frequency can be controlled when using VSC-HVDC. Figure 3.1 represents the control structure of the VSC-HVDC transmission system.
Nagwa F. Ibrahim, Sobhy S. Dessouky

Chapter 4. VSC-HVDC Under AC and DC Fault Conditions

Abstract
This chapter will examine high-voltage direct current (HVDC) system responses to DC and AC faults from a theoretical perspective. The analysis will consider the HVDC topology two-level voltage source converter (VSC). The test system is shown in Fig. 4.1, where the location of faults is also illustrated. The investigation is concerned with system responses for faults located at the converter DC or AC bus, which is the worst-case fault location, and it is representative for faults further away from the converter. It is presumed that faults will not happen closer to the converter, because this area is located in the valve hall and faults are unlikely. If faults happen closer to the converter, then the fault current will be too fast and strong for the normal protection methods, and insulated gate bipolar transistors (IGBTs) will be tripped by the internal switch-level protection.
Nagwa F. Ibrahim, Sobhy S. Dessouky

Chapter 5. VSC-HVDC Simulation Results

Abstract
The system considered in this book is given in Fig. 5.1. The HVDC system consists of two VSCs connected via a DC link. The control of converter VSC-1 is done by using DC voltage control, whereas the control of converter VSC-2 is done by active power control. In this chapter, the steady-state and transient behavior of control schemes in normal and fault conditions a VSC-based HVDC connected to a grid is studied. The mutual effect between the VSC-HVDC performance and its control scheme dynamics is investigated. It is that the control scheme that uses is vector control and hysteresis current control. The different methods of calculating the reference current to control VSC behavior under different disturbance conditions are investigated. Different types of faults and protection scheme of VSC are also investigated.
Nagwa F. Ibrahim, Sobhy S. Dessouky

Chapter 6. Experimental Investigation for HVDC System

Abstract
In recent years, the wide array of digital devices is available for developing drive system. Unlike the analog controllers, the digital controllers allow implementation of sophisticated operating algorithms, offering significant technical advantages, thanks to their ability of fast processing of vast data, high operational flexibility, and ease of integration into automated industrial systems. In recent years, the digital signal processors (DSPs1104) have been enjoying increased interest and implementation in control of electrical systems. The advantages of the DSP1104 are flexibility, insensitivity to aging effects and for thermal drifts, ease of implementation and upgrade, and, on the other hand, it is available at low prices. As an integrated part of this work, an attempt is made to verify the control scheme experimentally. This chapter describes the details of all the hardware that are used to verify the effectiveness of the proposed scheme.
Nagwa F. Ibrahim, Sobhy S. Dessouky

Chapter 7. Conclusions and Future Work

Abstract
The mathematical model of VSC-HVDC system is discussed in this book. Various abnormal conditions are simulated through the “MATLAB/Simulink” at both the grid terminals and the DC transmission line where it is connected to between two converters. Different control strategies are proposed for the VSC-based HVDC system. The behavior of different faults is studied under the different disturbances. The relay is used to protect the converter from grid current feeding during DC fault. In atrial to control the VSC-based HVDC system, active and reactive control under AC fault method is employed in this work to properly design the VSC control schemes. The following are the major outcomes of the study:
Nagwa F. Ibrahim, Sobhy S. Dessouky

Backmatter

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