Hvdc can be transmitted through cables both underground and underwater. The electric power industry is faced with difficulties in acquiring rightofways. For large power transmission over long distances, the hvdc proves to be economical and efficient over high voltage ac hvac transmission system. The reasons for selecting hvdc instead of ac for a specific project are often numerous and complex.
Hvdc light, based on vsc technology voltage sourced converter, is designed to. Below is the hvdc light model defined in a symdef file. Hvdc light rating increase to 1100 mw elements common to existing systems igbt chip igbt submodule igbt stakpak igbt module or stack control system cooling system dc capacitor increased dc current six submodules per stakpak rather than four increased dc voltage 150 kv to 320 kv valve stacks comprised of igbt modules with 26 positions arranged horizontally. Principlesof hvdc controls convertercontrol functions, dc voltagecontrol 1. A monopolar hvdc system with ground return consists of one or more sixpulse converter units in series or parallel at each end, a single conductor and return through the earth or sea, as shown in figure 2.
Influence of embedded hvdc transmission on ac network. It was superior in its ability to control the alternate current ac voltage, phase angle and currents compared with the classic hvdc technology. To date, six hvdc light transmission systems have been put into operation, of which two, gotland light. Hvdc transmission and reactive power compensation with voltage source converter vsc technology has certain attributes which can be beneficial to overall system performance.
Mainly due to the extra conversion equipment and maintenance difficulty. And in 1997 a completely new converter and dc cable technology called hvdc light was introduced. When the technology was introduced it was based on a twolevel. Other abb hvdc light high voltage direct current systems in operation. Analysis of hvdc and hvdc light technology 7 figure 1. Hvdc transmission utilizes a converter station at either end of the system. As its name implies, hvdc light is a high voltage, direct current transmission technology and is well suited to. The technology can use overhead lines or environmentally sound oilfree underground and underwater cables.
Apr 27, 2017 the new voltage sourced converter vsc technology was called hvdc light to resemble a more elegant, lighter and agile version of hvdc. Hvac 3phase lower transmission loss because of no reactive loss lower insulationclearance of conductor dc voltage is about 71% of the ac peak voltage. S time to connect 01 02 01 the gotland 1 valve hall from the 1950s. Neplan network with a user defined model of the hvdc link. Model predictive control of voltage source converter in a hvdc system mohammad amin and marta molinas dept. Existing connection under construction future plan. This wire would be at a high voltage 60,000 volts for the proposed system. The new technology, hvdc light, is well suited to meet the new markets and its demands and the reasons for this are explained. Hvdc light its time to connect new england clean power link. The shortcircuit power from the ac grid at the connection point in nas is less than 60 mva. An embedded hvdc system is a dc link with at least two ends being physically connected within a single synchronous ac network. High voltage direct current hvdc transmission, is a major user of power electronics technology. The project will finish in 2020 and all public material can be found on the project website. It is used to transmit electricity in lower power ranges from under 100 to 1,200 mw over short and medium long distances.
In figure 2 there are different types of cables used for different puposes and locations. During the north american blackout of 2003, it was an important power supply route keeping long island. Hvdc light can efficiently aid grid restoration after a blackout. The two terminologies, hvdc light and vsc hvdc, have been used interchangeably in this report. The operating range of the ideal converter theory from 0. Hvdc classic transmission current source converters line commutated thyristor valves requires approx. Power transmission reactive power control in both connected ac networks. Nu, with input from new england iso and ui, has outlined criteria that must be satisfied by the underground hvdc solution. As it is a relatively new technology when compared to the more mature classic hvdc, many studies are aimed at operation and stability of vschvdc interconnecting ac grids.
Hvdc light is a powerful tool for damping angle electromechanical. The cross sound cable project, a 40kilometer long, 330megawatt hvdc light underwater cable transmission between connecticut and long island near new york city. It is also faced with the challenge of integrating renewable power sources into an ac power system. Model predictive control of voltage source converter in a. As its name implies, hvdc light is a high voltage, direct current transmission technology and is well suited to meet the demands of competitive power market for. Compared to alternating current, the direct current system is less expensive and loses less energy. Because of the massive equipment needed to increase the dc voltage for transmission, early hvdc applications were limited to moving a lot of power over long distances. The hvdc plus from siemens, hvdc light from abb and hvdc maxsine from alstom are examples of the implementation of the mmc concept in applications for vsc hvdc transmission 1415.
For longdistance transmission, hvdc systems may be less expensive and. Hvdc transmits great amounts of electrical power over long distances. The new voltage sourced converter vsc technology was called hvdc light to resemble a more elegant, lighter and agile version of hvdc. The hvdc light converter station normally fol lows the ac voltage of the connected grid. In vschvdc transmission scheme, the switching of igbt valves depends on a pulse width modulation pwm. Worlds most powerful link commissioned capacity up 10 times. The voltage magnitude and frequency are determined by the control. Principles of hvdc controls control of dc voltage dc voltage is varied by means of a converter bridge in rectifier operation the power flow is from the ac system to the dc system the power flow is changed from the dc system to the ac system by reversing the dc voltage. Hvdc light system hvdc light is a transmission system in one abb turnkey delivery including cables, converters, transformers etcetera. Vschvdc control and protection the control and protection system is the brain of pcs9520 vschvdc transmission system. Abb has the capability to provide the complete chain of services from design to commissioning.
The hvdc light technology, developed by abb and based on voltage source. At this point the wind power production is connected for the hvdc light system to transmit the power to the north. High voltage direct current hvdc transmission finally proved to be technically feasible. Hvdc circuit breakers are difficult some mechanism must be included in the circuit breaker to force current to zero. Simulation of vsc based hvdc transmission system for the integration of windfarm into grid international journal of electrical and electronics engineering ijeee, issn print. It is a high voltage, direct current transmission technology i. Due to advantages provided by hvdc light, it is used in the following applications. Pdf voltage source converter vsc based hvdc transmission technology has been selected as the basis for several recent projects due to its. For longdistance transmission, hvdc systems may be less expensive and have lower electrical losses. Currently, two viable power electronic device options exist, leading to two families of hvdc converters. Dolwin2 900 mw hvdc light transmission english pdf brochure. One of the most important of all the cables is submarine cables, it supplies power to islands.
Lorand bede for their support and discussions during the complete master program. Hvdc disadvantages hvdc is generally less reliable and has lower availability than hvac. Hvdc transmission system basics, block diagram, working. Hvdc light technology with underground dccables has been implemented in a competitive, marketoriented network service. 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. The literature presented in this paper is particularly useful for researchers working in the field of hvdc and asynchronous power sharing over existing hvac networks. Since then the progression to higher voltage and power ratings for these converters has roughly paralleled that for thyristor valve converters in the 1970s. Note that voltage source converters vsc are used in abbs hvdc light technology. One of the important power electronics field application is high voltage dc hvdc transmission system. The project does not only perform the demonstrations of different hvdc breakers, it also gives recommendations of how to test hvdc breakers, and insight into typical requirements and expectations of hvdc breakers in a grid. High voltage direct current hvdc technology is a promising solution for delivering largescale renewable energy with a long transmission distance because of the reduced power losses and low.
The igbtbased siemens hvdc plus is build out of selfcommutated systems with indirect voltage link voltagesourced converters, vsc and operates with the newest type of the modular multilevelconverter mmc, which is used in the ultranet project, and has a transmission capacity up to 2000 mw at a. Hvdc technology first made its mark in the early undersea cable interconnections of gotland 1954 and sardinia 1967 and then in longdistance transmission with the pacific intertie 1970 and nelson river 1973 schemes using mercuryarc valves. A high voltage, direct current hvdc electric power transmission system also called a power superhighway or an electrical superhighway uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current ac systems. The hvdcplus from siemens, hvdclight from abb and hvdcmaxsine from alstom are examples of the implementation of the mmc concept in applications for vschvdc transmission 1415.
Inverter ud control no change in dc voltage, but change in dc current. In this post let us see how hvdc transmission system works. Hvdc light was launched in 1997 and is an adaptation of classic hvdc. It provides monitoring, control and protection of all equipment in vschvdc transmission system and converter station. As an example, the directlink hvdc light project, connecting new. Hvdc transmission based on current sourced converters has been in use for 50 years. The voltage support, frequency support and fast time response provided by hvdc light are much needed during such conditions. Hvdc light a new technology for a better environment english pdf article hvdc light a transmission vehicle with potential for ancillary services english pdf article hvdc light and development of voltage source converters english pdf article hvdc light, a tool for electric power transmission to distant loads english pdf. Hvdc transmission and integration ac grid 1 rightofway comparison of 6,000mw hvdc and ac circuits joe mooney is a department manager at power engineers, inc. This file will be compiled from matlab to a dll % definitions. Modeling and control of vschvdc links connected to. Hvdc and facts transmission technologies available today offer the planner increased flexibility in meeting transmission challenges.