High Voltage Direct Current Technology Research Articles

High voltage direct current (HVDC) transmission: Future expectations for Pakistan

An HVDC transmission system for bulk power transfer over longer distance offers numerous advantages over an alternating current (AC) transmission system, such as direct integration of networks operating at different frequencies, comparatively low line losses on account of constant current and absence of reactance. This paper presents details about HVDC power transmission systems and power converter technologies. Issues concerning integration of electrical power generated by alternate sources (i.e., wind, onshore and offshore) into the national grid of Pakistan using HVDC technology are also discussed. Research studies revealed that the energy crisis of countries like Pakistan can be mitigated to a larger extent with the use of HVDC transmission systems.

Methodology for mapping operational zones of VSC-HVDC transmission system on offshore ports

This research proposes a methodology for mapping operational zones of transmission systems based on voltage source converter high voltage direct current technology (VSC-HVDC) linking offshore ports to onshore power grid. Various operational conditions are investigated using the simulation software PSCAD in order to evaluate the feasibility of application of VSC-HVDC technology on offshore ports whereas supporting three economic activities: transshipment, subsea mining and power generation. The electrical power source considered in this research is based on nuclear energy or driven by fossil fuel. Varying the settings of the HVDC control strategy as well as the power balance within the offshore port and running several simulations on the power system, the power and voltage profiles in the generation, distribution and transmission of the system can be evaluated in details. Based on the methodology, stability boundaries in the HVDC system can be defined and mapped for reliable operation of the system during unusual and critical scenarios.

Using a VSC Based HVDC Application to Energize Offshore Platforms from Onshore – a Life-cycle Economic Appraisal

Abstract The consequential growth in offshore electrical power demand associated with increased oil and gas production, new offshore developments and advanced technologies for enhanced oil recovery is driving the decision to explore alternative means of power supply as opposed to solely considering localized gas turbine generators, the last being the conventional approach over the decades. As part of the overall strategic decision making process, which would include consideration of a numerous other technical issues, this paper presents a Reliability Constrained Integrated Energy Economics Model (RC-IEEM) as a tool to allow for the economic comparison between two strategic electrification options namely (i) continue with offshore localized power generation using large-scale gas turbines (GTs), or (ii) propose a new approach for power supply from onshore using a voltage source converter (VSC) based high voltage direct current (HVDC) technology. Results reported in this paper show usefulness of the proposed tool and the benefits of connecting to onshore using HVDC technology, offering lower life-cycle cost with higher reliability and lower environmental impacts. The assumptions and conclusions reached in this paper are generic and are not project specific but are typical for the offshore oil and gas industry.

A new approach for optimal reactive power flow of MTDC systems using the ABC algorithm

This paper presents a new approach to optimize reactive power flow of multiterminal high voltage direct current (HVDC) systems. Successful application of two-terminal DC systems worldwide makes the use of multiterminal direct current (MTDC) systems more attractive. Due to the economic and technical advantages of HVDC technology, MTDC systems have been used extensively in recent years. In this study, the artificial bee colony (ABC) algorithm is used for solution of the optimal reactive power flow problem of MTDC systems. In opposition to the current-balancing method used in the literature, this study represents a new approach for DC system power flow calculations. The proposed approach is tested on a sample IEEE MTDC test system. The results by the proposed approach are compared with those reported in the literature. Thus, the applicability and the efficiency of this approach used together with the ABC algorithm are shown.

The Future Expansion of HVDC Power Transmission in Brazil: A Scenario-Based Economic Evaluation

We discuss the expected future needs of the Brazilian electric grid operators for High Voltage Direct Current (HVDC) transmission lines against the background of a changing electricity sector in Brazil. On account of the spatial mismatch between the additional generation potential and the expected future electricity demand, a need for investments in long-distance transmission capacity is postulated. Due to the low losses incurred, HVDC technology is particularly suitable for this. For the analysis, we use different expansion scenarios for the year 2035 that are mainly based on hydropower or alternative renewable energy sources (primarily wind and solar power). Linear optimization is used to determine the optimal HVDC transmission lines to connect regions. The results show that large investments in HVDC transmission are needed, especially in the case of hydropower expansion, and that transmission capacity is a critical factor in the process of expanding the renewable energy generation capacity in Brazil.

A Directional Protection Scheme for HVDC Transmission Lines Based on Reactive Energy

High-voltage direct-current (HVDC) transmission-line protection is becoming increasingly desirable with the expanding worldwide popularity of HVDC technologies in recent years. This paper proposes a transmission-line backup protection scheme based on the integral of reactive power for HVDC systems. The directional characteristics of reactive power flow are theoretically analyzed for internal and external faults, and these characteristics are used to construct a directional protection scheme. The Hilbert transform is adopted to calculate the reactive power, which ensures a continuous output of calculation results and improves the reliability of the protection. A bipolar 12-pulse HVDC test system based on the CIGRE benchmark is modeled using PSCAD/EMTDC, and extensive simulations of various fault situations are conducted to test the effectiveness of the proposed scheme. The simulation results show that the proposed protection scheme correctly identifies internal and external faults and performs well with different fault distances and fault resistances. Furthermore, the proposed protection is insensitive to the sampling frequency, making it practical for future applications.

Technical Issues Associated with the Connection of Nuclear Power Plants to the National Electricity Transmission System via High-Voltage Direct Current Technology

This article highlights some of the key technical issues associated with the connection of large modern nuclear power plants (NPPs) to the national electricity transmission system via high-voltage direct current (HVDC) technology. The importance of the electricity system for such a connection is described. The need for reliable and secure supplies from the electricity grid to power the safety systems of the NPP is also discussed. Simulations carried out on the power system computer-aided design have highlighted the susceptibility of HVDC current source converter technology to commutation failure under a three-phase fault condition at the inverter when connected to a weak ac system. The work has also demonstrated the fault ride through the capability of the voltage source converter technology for the same scenario.

Power electronics in smart grid power transmission systems: a review

Increasing development of high-voltage high-power semiconductor technology continues to have a great impact on the progress of advanced power electronic apparatus used to optimised operations and efficient management of smart grids. Development of smart grid transmission power system is based on reliability of the flexible alternating current transmission system (FACTS) technologies and the high-voltage direct-current (HVDC) power transmission. The flexible alternating current transmission system anchored in power electronics, proposes an opportunity to improve controllability, stability, and power transfer capability of AC transmission systems. In this review paper, several technical publications related to FACTS installations have been highlighted and performance comparison of different FACTS controllers has been discussed. An overview of the recent advances in the area of voltage source converter (VSC) HVDC technology used in smart grid is provided. Selected key multilevel converter topologies are presented. Control and modelling methods are discussed. A hybrid FACT and VSC-based HVDC installations used in smart grid is specified.

Investigation of multimodule buck–boost inverter‐based HVDC transmission system

In high voltage direct current (HVDC) systems, the semiconductor devices have to be connected in series to obtain the required high-voltage ratings. This study proposes a new HVDC configuration, namely, multimodule buck–boost inverter for HVDC transmission applications which avoids series connection of large number of semiconductor switches. In addition, it provides a blocking capability against DC side faults. The proposed configuration consists of several simple buck–boost converters which are assembled together to meet the requirements of high-voltage high-power applications. This paper studies the dynamic performance of the proposed system under different operating conditions, and the results were satisfactory. The main advantages of the proposed configuration are: (i) pure sinusoidal output which minimises/eliminates the requirements for supplementary AC filters and offers an inherent suppression to the common mode voltages, (ii) very low dv/dt stresses and (iii) complete blocking capability of AC side contributions during DC side faults. This study discusses the system architecture, passive components selections, voltage and current ratings of its semiconductor devices and the required controllers. A comparison between the proposed configuration and other existing HVDC technologies is also presented in this study.

HVDC DC CT 선형성 최적화 및 시스템 적용에 대한 연구

These days, the advantages of DC power system are consistently stand out in korea that was a small power loss and high stability. Needs of DC power transmission technology is focused In the midst of a smart grid and environment friendly generation technology boom that is needed for next generation technology. Researches and businesses for HVDC(High Voltage Direct Current) system has been began. But, Needs of HVDC equipment and system commissioning technology are not on the rise until now. In particular, South Korea’s HVDC technology is after the foot runner of advanced country and company. In addition, There is no experience for equipment verification and commissioning technology. And Experts of HVDC are rare. Who has been fully understood hardware and system as a whole, and identified all the equipment’s characteristic. Recently, Academia and industry are recognized a needs of HVDC technology. But it does not received a recognition of technical value. In this paper, introduce issues when we apply the IEEE’s verification method for HVDC system, especially DC current measurement system, DC CT(Direct Current Transformer), among the HVDC equipments. And Proposes remedial methods on the issue in order to recognize the necessity that was HVDC equipments’s verification and commissioning technology research should be focused on.

Investigations of the Energy-Saving Technology of a Cloud Computing Data Center

This paper shows the energy consumption distribution of current data center, presents some effective energy-saving measures to reduce the energy consumption of a cloud computing data center. Raise an effective way to optimize the air distribution of the data center such as sealing the cold passageway. Through the use of ADU can solve the local overheating inside the equipment cabinet. The use of the modularization UPS, the high-voltage direct current technology and harmonic suppression can improve the efficiency of the power supply system.

Research on DC Voltage Control Strategies for Typical Four-Terminal HVDC System

The continuous development of alternative energy has put forward higher requirement for electricity transmission. To cope with its fluctuation characteristics, high voltage direct current (HVDC) technology has received more attention. Voltage Source Converter (VSC) based Multi-Terminal High Voltage Direct Current (MTDC) represents the future trend of HVDC technology. This paper mainly focuses on the control strategies of a four-terminal VSC based MTDC power transmission system. The operation characteristic of the system was studied, and the proposed two control strategies, master-slave control strategy and DC voltage droop control strategy, were verified through simulations. The latter control strategy was proved to be performing well under various conditions, including converter station disconnection and faults at AC side of the converter.

Analysis of Power Sharing and Voltage Deviations in Droop-Controlled DC Grids

This paper analyzes the influence of the converter droop settings and the dc grid network topology on the power sharing in a dc grid based on voltage source converter high voltage direct current technology. The paper presents an analytical tool to study the effect of the droop control settings on the steady-state voltage deviations and power sharing after a converter outage, thereby accounting for dc grid behavior. Furthermore, an optimization algorithm is developed, taking into account two conflicting optimization criteria. The simulation results show that, when selecting appropriate values for the converter gains, a tradeoff has to be made between the power sharing and the maximum allowable dc voltage deviation after an outage.

HVDC Circuit Breakers: A Review Identifying Future Research Needs

The continuously increasing demand for electric power and the economic access to remote renewable energy sources such as off-shore wind power or solar thermal generation in deserts have revived the interest in high-voltage direct current (HVDC) multiterminal systems (networks). A lot of work was done in this area, especially in the 1980s, but only two three-terminal systems were realized. Since then, HVDC technology has advanced considerably and, despite numerous technical challenges, the realization of large-scale HVDC networks is now seriously discussed and considered. For the acceptance and reliability of these networks, the availability of HVDC circuit breakers (CBs) will be critical, making them one of the key enabling technologies. Numerous ideas for HVDC breaker schemes have been published and patented, but no acceptable solution has been found to interrupt HVDC short-circuit currents. This paper aims to summarize the literature, especially that of the last two decades, on technology areas that are relevant to HVDC breakers. By comparing the mainly 20+ years old, state-of-the art HVDC CBs to the new HVDC technology, existing discrepancies become evident. Areas where additional research and development are needed are identified and proposed.

HVDC, the Next Generation of Transmission: Highlights with Focus on Extruded Cable Systems

AbstractOur world carries an increasing burden of increasing CO2 emissions. Rather than rationing the use of electric power, we should all together organize ourselves toward a positive solution that benefits growth and a sustainable society. The high voltage direct current (HVDC) technology is a cornerstone that makes it possible to transport sustainable energy to the regions of consumptions that are often far away from the location of generation. Today's commercially available highest HVDC transmission voltage is 800 kV. This system makes use of classic converter stations. The newer HVDC Light technology, Voltage source converters (VSCs) and extruded cable systems, that are commercially available, are characterized today by a highest voltage of 320 kV and 1000–1200 MW of transmission power. This paper describes the need for higher HVDC transmission powers, the general technology of the VSC stations, and an in‐depth description of HVDC technology with a focus on extruded cable systems. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The History of High Voltage Direct Current Transmission

Transmission of electricity by high voltage direct current (HVDC) has provided the electric power industry with a powerful tool to move large quantities of electricity over great distances and also to expand the capacity to transmit electricity by undersea cables. The first commercial HVDC scheme connected the island of Gotland to the Swedish mainland in 1954. During the subsequent 55 years, great advances in HVDC technology and the economic opportunities for HVDC have been achieved. Because of the rapid development of HVDC technology many of the early schemes have already been upgraded, modernised or decommissioned. Very little equipment from the early schemes has survived to illustrate the engineering heritage of HVDC. Conservation of the equipment remaining from the early projects is now an urgent priority, while the conservation of more recent projects, when they are retired, is a future challenge.

Design Concepts for High-Voltage Variable-Capacitance DC Generators

The transmission requirements of the next generation of offshore wind farms, such as the Round Two U.K. offshore development proposals, may rely on high-voltage direct current (HVDC) technology for at least a part of their power collection and transmission requirements. HVDC technology is particularly suited for the transmission of high powers through large lengths of submarine cables; however, its application is limited by the high cost of offshore ac-dc converter stations. This paper therefore investigates the feasibility of the direct generation of HVDC power using a novel generator topology, as an alternative solution to the generation-transmission requirements of large offshore wind farms. A variable-capacitance generator uses electrostatic fields to generate an HVDC output with a minimum of power conditioning and is based on a previous work that suggests system power densities comparable with the conventional generator-transformer-rectifier systems to be achievable.