In the transient process of cable line, if a fault occurs over the cable line, the current measured at both convert stations would have the same changing direction and the signs of the fault component current at both convert stations are the same to each other. Both types of dc transmission cschvdc and vschvdc are mature technologies. Frequencydomain analysis will be applied to examine the. Hvdc vsc technology allows overhead lines or land cable systems, i. Facts devices and hvdc transmissions have emerged as solutions to help power systems to increase the stability margins. A model of a threeterminal vschvdc system is presented in this thesis. Control of vsc based hvdc transmission system for o shore wind power plants semester. For longdistance power transmission, hvdc lines are less expensive, and losses are less as compared to ac transmission. It interconnects the networks that have different frequencies and characteristics. Hvdc transmission based on current sourced converters has been in use for 50 years. Fault location identification for a vschvdc system with a long hybrid transmission medium by hashim abbas m. A classic hvdc transmission typically has a power rating of several hundreds. Ac grid with embedded vsc hvdc for secure and efficient power delivery english pdf article vsc hvdc control and application in meshed ac networks english pdf article 800 kv hvdc alternative scenarios for long distance bulk power transmission english pdf article sapei hvdc converters english pdf article. Vsc hvdc 1 x 400 kv 1200 a 1620 mm 2 conductors hvac 2 x 400 kv 2 x 1200 mm 2 conductors energy losses transmission line km 500 5% 10% hvac.
Applications for highvoltage direct current transmission. This paper tries to follow and summary the important researches and development of vsc hvdc technology, especially in the vsc topology, modelling and control methods, and potential applications in the power system. This is the first hvdc transmission where lcc and vsc poles cooperate in a bipole. In contrast to linecommutated hvdc transmission, the polarity of the dc link voltage remains the same with the dc current being. Nonlinear control and stabilization of vschvdc transmission. Develop a report to the psrcc describing voltage source converter vsc hvdc systems and the impact on local ac sy stem protection. Impact of voltage source converter vsc based hvdc transmission on ac system protection. The application of vsc technology in hvdc transmission was introduced as hvdc light by abb in 1997 and the first system went into service in 1999.
Dc impedancemodelbased resonance analysis of a vsc. First voltage source converter for transmission in gotland, sweden,1999 hvdc installations in the world today since the first commercial installation in 1954 a huge amount of hvdc transmission systems have been installed around the world. Dc impedancemodelbased resonance analysis of a vschvdc system. Vsc application for hvdc systems of high power rating up to 200mw which are currently in discussion for several projects are mentioned. The embedded fullbridge type hybrid mmc suitable for overhead line vsc hvdc transmission system. Understanding of tuning techniques of converter controllers. Adoption of a voltage source converter vsc hvdc transmission to a long distance. There are also some further possibilities for the improvement of vsc hvdc. Components of hvdc high voltage direct current capacitor. Planning and control of expandable multiterminal vschvdc. The voltage source converter highvoltage direct current vschvdc project has the advantages of independent and rapid control over active and reactive power 1. Hvdc a key solution in the future transmission system abb group.
A hierarchical control system was implemented to successfully overcome these. Early hvdc systems, built until the 1930s, were effectively rotary converters and used electromechanical conversion with motorgenerator sets connected in series on the dc side and in parallel on the ac side. Vscbased hvdc transmission system detailed model matlab. Planning and control of expandable multiterminal vschvdc transmission systems. Vschvdc transmission systems are used for 400500 mw power transmission and cschvdc system for higher power transmissions.
In order to fully utilize the potential of the vschvdc system for weakacsystem connections, a novel control method, i. The transbay cable tbc is the worlds first inservice mmc vsc. Highvoltage direct current hvdc transmission has been in commercial operation since the 1950s. Mar 11, 2015 hvdc transmission is an efficient technology designed to deliver large amount of electricity over long distances with negligible losses. A technical report to the system protection subcommittee. Chapters on hvdc line and simulation tools were updated. Vsc hvdc is a new dc transmission system technology. A novel pilot protection principle for vschvdc cable. The worlds first 5terminal 200 kv vschvdc project was put into service on 4 july 2014. The voltage source converter high voltage direct current vschvdc project has the advantages of independent and rapid control over active and reactive power 1. The hvdc system which transfers energy between the ac buses at the same location is called backtoback system or an hvdc coupling system. Hvdc and facts transmission technologies available today offer the planner increased flexibility in meeting transmission challenges. Utilizing hvdc links for longdistance transmission and for interconnecting.
Bipole and monopole are being used and tripole is under investigation. In this paper, dc resonance issues will be investigated for a twoterminal vschvdc system. In this thesis, the modeling and control issues for vschvdc links connected to weak ac systems are investigated. Offshore wind power farms are usually located on the continental shelves, far. Chinas first vschvdc transmission for wind farm integration ceprisubsidiary of sgcc delivered the complete transmission system, including design, manufacturing, testing and commissioning. The embedded fullbridge type hybrid mmc suitable for overhead. Long distance transmission by overhead line or insulated submarine or underground cable or a combination of these. A similar arrangement was the hvdc interisland in new zealand after a capacity upgrade in 1992, in which the two original converters using mercuryarc valves were parallelswitched feeding the same pole and a new third thyristor converter installed with. The basic layout of 2level vschvdc system under the dc poleground fault on the dc transmission line shown in fig. Hvdc vsc hvdc light transmission operating experiences. The massive transmission of electricity in the form of dc over long distances by means of submarine cables or overhead transmission line is the high voltage direct current transmission. High voltage direct current hvdc power systems use d. Hvdc reference book update all 24 chapters in a few years. Effectively improve the wind farms low voltage ride through capability.
Design, control, and application of modular multilevel. This project connects chinas mainland to five isolated islands. The principal characteristic of vsc hvdc transmission is its ability to independently control the reactive and real power flow at each of the ac systems to which it is connected, at the point of common coupling pcc. High voltage dc transmission system electronics hub.
Multiterminalhvdc mhvdc can be built using vsc technology. A new approach for compaction of hvdc transmission lines. A description of the control system is provided in the vsc based hvdc link case study of the users manual. For analysis of the complete vschvdc system, this paper starts from developing an understanding of a vsc from the control point of view. A number of hvdc vsc transmission installations, both globally as well as here in australia, have now been in operation for quite a few years. The worlds first commercial hvdc transmission link, was built in 1954 between the swedish mainland and the island of gotland, with a rating of 20 mw, 200 a and 100 kv. Converters vsc technologies for range of schemes including overhead line point to.
The contribution of vsc hvdc to short circuit currents is investigated in 29. Both systems can be monopole, bipole and tripole types. High voltage direct current hvdc transmission finally proved to be technically feasible. Transmission system vsc valve vsc valve v1 vsc valve v2 ac. Al hassan bachelor of science in electrical engineering, university of pittsburgh, 2010 submitted to the graduate faculty of swanson school of engineering in partial fulfillment of the requirements for the degree of master of science. Hierarchical control in a 5terminal vschvdc project ee. P 2 the voltage sourced converter single phase steady dc vsc voltage. Modeling and control of vschvdc links connected to weak ac. A description of the control system is provided in the vscbased hvdc link case study of the users manual.
Introduction to hvdc vsc usaid sarienergy integration. Figure 1 shows, by region, the different hvdc transmissions around the world. Vschvdc is a new dc transmission system technology. The interarea decoupling and local area damping by the vsc hvdc are studied in 30.
Current source or line commutated hvdc systems have been used extensively on land in the past but for offshore wind farms voltage source hvdc is now considered to be more attractive for wind farms, an hvdc system is formed by a rectifier connected to the. It is based on the voltage source converter, where the valves are built by igbts and pwm is used to create the desired voltage waveform. Hvdc transmission requires a converter at each end of the line. High voltage direct current hvdc transmission system market. Converter topologies in vschvdc systemsan overview ijert. The project was a 50 mw underground cable, interconnecting the southern part of the island of gotland with the northern end 4. Control of vscbased hvdc transmission system for o shore wind power plants semester. High voltage direct current hvdctransmission systems. The system configuration of a vsc hvdc connection for an offshore wind farm is illustrated in fig. Design, control and application of modular multilevel converters for hvdc transmission systems is a comprehensive guide to semiconductor technologies applicable for mmc design, component sizing control, modulation, and application of the mmc technology for hvdc transmission. The underlying technology of vsc based hvdc systems, its characteristics and the working principle of vsc based hvdc system are also. Hvdc transmission is an efficient technology designed to deliver large amount of electricity over long distances with negligible losses. The principal characteristic of vschvdc transmission is its ability to independently control the reactive and real power flow at each of the ac systems to which it is connected, at the point of common coupling pcc.
Siemens introduced their version of vsc technology called hvdc plus power link universal system in 2007 and alstom grid has a vsc technology called maxsinetm. The project presented some significant technical challenges, especially with regards to the control and protection of the five terminals. Due to the controllable ac output voltage and frequency of vsc hvdc links, they. Typical vschvdc controls and a practical dc transmission line will be assumed. This paper presents a novel pilot protection principle for vsc hvdc cable lines based on fault component current. At tgs, we perform all steady state, short circuit, transient stability, ssr and emt studies that are needed to study an hvdc project. Modeling and control of vschvdc transmissions diva portal. Vschvdc can limit rotor acceleration by fast power runup or rundown control functions immediate power reversal if needed vschvdc can improve dynamic stability considerably by modulating p and keeping a tight control over voltage modulating q while maintaining scheduled p combining with widearea monitoring and control system wamswacs. Development and commissioning of the first vschvdc. The use of voltage source converter based high voltage direct current vschvdc sys tems is considered to be a major step in facilitating long distance power transfer and integrating remotely located renewable energy sources to major consumption centers. Introduction sustainable energy generation like hydro, wind, sun and waves are normally not located close to the consumption. Review of vsc hvdc connection for offshore wind power. Siemens introduced their version of vsc technology called hvdc plus power link universal system in 2007 and alstom grid has a.
Hvdc transmission is presently being considered for large offshore wind farms located far away from the land based grid. The essential components in a hvdc transmission system are 61224 pulse converters, converter transformer with suitable ratio and tap changing, filters at both dc and ac side, smoothening reactor in dc side, shunt capacitors and dc transmission lines. Progress in hvdc grid protection for moorthy subramanian, and linash kunjumuhammed. High voltage direct current systems ge grid solutions. However, cschvdc transmission is more appropriate for large power.
On the norwegian shelf, co2 taxation already today in effect makes. This fact makes transmission of the power as almost as essential as the generation. Hvdc transmission lcc and vsc hvdc projects are on the rise around the world, in particular, vsc hvdc projects are gaining significant popularity. Comparative study of hvac and hvdc transmission systems. Dc circuit is short within the same buildingstation. What is hvdc high voltage direct current transmission. Typical vsc hvdc controls and a practical dc transmission line will be assumed. The advantages of the vsc hvdc transmission technology make it more suitable than other transmission systems hvac, cschvdc for the grid connection of offshore wind farms. Hvdc transmission and reactive power compensation with voltage source converter vsc technology has certain. Vsc hvdc transmission supporting variable electricity generation.
There are two types of hvdc, the classic technology using thyristors for conversion, and vsc voltage source converters technology, by abb called hvdc light, which uses transistors igbts for conversion. The worlds first commercial hvdc link situated between the swedish mainland and the island gotland was delivered by abb in the year of 1954 with the capacity of 20mw, 100kv inrtoduction the longest hvdc. Topologies of multiterminal hvdcvsc transmission for. The backtoback system provides an asynchronous interconnection between the. In backtoback hvdc stations, the converters and rectifiers are installed in the same stations. The transbay cable connects pittsburg converter station to potrero converter station near san francisco via submarine cable. In this paper, dc resonance issues will be investigated for a twoterminal vsc hvdc system. Customized high voltage direct current hvdc solutions for utilities. New technologies of voltage source converter vsc for hvdc transmission system based on vsc, power and energy society general meeting conversion and delivery of electrical energy in the 21st century, 2008 ieee, 2024 july 2008, pittsburgh, pa. This type of transmission is preferred over hvac transmission for very long distance when considering the cost, losses and many other. Vsc technology segment anticipated to register high yoy growth over the forecast period. Modeling and control of vschvdc links connected to weak.