Hvdc transmission line protection based on transient power. Vsc hvdc c t d ivsc hvdc converter design with fault blocking. In 1995 abb announced a new concept for hvdc converter stations, hvdc with capacitor commutated converters ccc, which further improves the performance of hvdc transmissions. High voltage direct current hvdc power systems use d. The same protection action is implemented as for a dc line, but without the restart attempt.
Recently mtdc grids have become more technically feasible due to improvements in vsc based converters, which can reverse currents and generally have greater control than lcc. In addition, it also includes the analysis and simulation of acdc system interactions which are of importance in the planning, design and operation of hvdc systems. As more of these systems are installed into the bulk power system, protection of the vschvdc systems must be a priority. The question of how to combine the two corresponding critical states when. Multiterminal hvdc is an important new technology for bulk power transfer from large sources of remote renewables to large load centers. Combining equation 8 and 9 the voltage sequence components can. Page 16 peter kohnstam hvdc business development export cables 2 length of export cables 200 km service life 30 years client tennet tso. Hvdc transmission technology is fast advancing and its applications are rapidly expanding.
These fault conditions need to be analyzed and simulated in detail for effective protection system prior to the development of practical highpower vschvdc networks. Also, tools for the system programming and supervision are. Hvdc control reactive power control the reactive power balance of each side of the hvdc transmission will normally be performed by reactive power controller rpc. Hvdc cable to bring power to long island during the peak summer season in july, august, and september. For multiterminal or meshed voltage source converter vsc highvoltage direct current hvdc systems, high speed protection against dc faults is essential, as power electronic components cannot. Hvdc is generally less reliable and has lower availability than hvac. However, in the case of a cableconnected system, a ground fault is almost always permanent, either by the failed cable insulation or the cable damage by an outside source. Pdf hvdc protection setting is difficult to be calculated analytically because of its. Full selective protection strategy for multiterminal cable hvdc grids. Hvdc, protection setting, procedure, fault quantities, pscad.
This document gives an overview of the hvdc protection. Peter kohnstam, 22 april 20, united states department of. Since the 60s, facts flexible ac transmission systems and hvdc high voltage direct current transmission have developed into a mature technology with high power ratings. Faults have to be cleared in a very short time range in order to minimize their impact on the system. Behavior of the hvdc system during fault is studied. Protection of multiterminal hvdc grids based on modular multilevel. Hvdc is also being increasingly applied in undersea and underground cable links. In order to meet the market demands, abb has a grid simulation center, located in sweden, where faults in the surrounding ac grids are simulated and the advanced control system of an hvdc grid is verified. Dc protections ac protections apparatus protective relays common features of the protection philosophy, the protective functions and the fault clearing actions are given. Converter faults, over current protection valve group, and dc line protection, circuit breakers. This paper proposes combining and connecting the double thyristor switches across. After analysing the characteristics of dc faults, protection methods need to be. Hvdc disadvantages hvdc is generally less reliable and has lower availability than hvac. The hvdc grid protection system is required to be i adequately fast to prevent damages andor converter blocking and ii reliable to minimize the impacts of faults.
Coordination of protection and vschvdc systems for. The control and protection system for the two converter stations shall be identical as far as possible. Such systems could be based on standardized system protection terminals, with customized functionality, tied together in a widearea protection system. Protection system reliability in the presence of hvdc and ac transmission systems at the same support structure christian romeis, matthias luther, johann jaeger fau erlangennuremberg kristian steckler, joerg reisbeck, timo keil transnetbw gmbh 1. This document gives an overview of the hvdc protection system. Control and protection of hvdc grids iii abstract the decarbonisation of europes energy sector is a key driver for the development of integrated hvdc networks or dc grids.
High voltage direct current and facts technology are shaping the grid of the future. Shortcircuit and ground fault analysis and locati on in. Power engineers can help you assess the benefits of using hvdc and facts technology for your project. Review of dc fault protection for hvdc grids li 2018 wires. The hvdc transmission system shall be stable in all situations and the system shall be selfprotecting with and without the interstation telecommunication in service. Design of protection schemes for multiterminal hvdc systems. Abstract smart grid is much more than it and smart meters. The protection and control system for a hvdc converter station shall be designed to ensure that no single failure of equipment shall cause the total failure of an hvdc system.
For this objective, very fast protection algorithms and reliable hvdc. Over voltage protection of converters, surge arresters. Economical even for shorter distances such as a few 10kmmiles 23. Multiterminal dc system line protection requirement and high. Vsc hvdc control and protection the control and protection system is the brain of pcs9520 vsc hvdc transmission system. The system which uses the direct current for the transmission of the power such type of system is called hvdc high voltage direct current system. Application based hvdc transmission types hvdc is an alternative for submarine transmission. For longdistance power transmission, hvdc lines are less expensive, and losses are less as compared to ac transmission. Pdf twolevel voltagesource converters and halfbridge modular multilevel. The purpose of the hvdc protection system is to promptly remove main circuit equipment from service at short circuits or at abnormal operation that might cause damage or interfere with the operation of the neighbouring system. High voltage direct current transmission peter kohnstam, 22 april 20, united states department of energy. A highvoltage, 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 fault should be effectively cleared by the hvdc line protection. Highspeed fault identification and protection for hvdc.
A high voltage, direct current hvdc 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 traditional protection system for the hvdc transmission line often uses the voltage and its change rate to detect. And in 1997 a completely new converter and dc cable technology called hvdc light was introduced. In hvdc systems, limiting fault currents is vital to protect. Coordination of protection and vschvdc systems for mitigating cascading failures r. 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. Jianping wang, bertil berggren, kerstin linden, abb ab sweden. Hvdc circuit breakers are difficult some mechanism must be included in the circuit breaker to force current to zero. On the short circuit current contribution of hvdc light. For long distance and high power transmission, highvoltage direct current hvdc transmission is a. A smartgrid is an electricity network that can intelligently integrate the actions of all users connected to it generators, consumers and those that do both in order to efficiently deliver. Mainly due to the extra conversion equipment and maintenance difficulty. The hvdc control and protection system is divided to two redundant systems a and b, based on an active standby concept. Challenges for protection of future hvdc grids energy.
A pilot protection for the hvdc transmission lines based on. High voltage direct current transmission, wiley eastern ltd. Presently, travelingwavebased protection and voltage derivative protection are usually used as the main protection for hvdc transmission lines, while backup line protections are composed of dc undervoltage protection and current differential protection 24. Protection of large partitioned mtdc networks using dcdc. Variation of transient power and the relation between various parameters of the line are analyzed during each fault. Simplified analytic approach of poletopole faults in mmchvdc.
Multiterminal dc system line protection requirement and. A distance relay estimates the electrical distance to the fault and compares the result with given threshold, which determines the protection zone 2. For longdistance transmission, hvdc systems may be less expensive and suffer lower electrical losses. Based on that the protection principle is developed. It shall be possible to repair, maintain and test the pole on outage whilst maintaining.
For long distance and high power transmission, high voltage direct current hvdc transmission is a. A protection system based on the characteristics of the ac. High voltage direct current hvdc transmission system has become a mature. High voltage direct current hvdc systems grid solutions. Use of facts and hvdc for power system interconnection and. Therefore, the converter is defenseless against dc side faults, such as a dclink shortcircuit, dc cable shortcircuits and dc cable ground faults. In vsc hvdc transmission scheme, the switching of igbt valves depends on a pulse width modulation pwm. Pdf a novel procedure for protection setting in an hvdc system. Faults on vschvdc line must be cleared with ultrahigh speed voltage direct current hvdc grid. For longdistance transmission, hvdc systems may be less expensive and have lower electrical losses. Pdf hvdc system control between different frequencies.
Dec 06, 20 application based hvdc transmission types upto 3000 mw hvdc represents the most economical solution to transmit electrical energy over distances greater than approx. Vschvdc bipolar grid based on novel distance protection scheme. Member, ieee abstractthis paper proposes a methodology to coordinate protection relays with a vschvdc link for mitigating the. The protection principle based on travelling wave theory gives the possibility of fastest protection. The reliability of hvdc systems has always been of primary concern in the planning and operation of power systems. 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. Summary of the observations of faults in a pointtopoint hvdc link. Commutationfailurepreventionforhvdc improvement in algorithm for commutation failure prevention in lcc hvdc masters thesis in electric power engineering. Hvdc systems utilize power electronics technology to convert ac and dc voltage, and are ideal for supporting existing systems or building new power highways. It provides monitoring, control and protection of all equipment in vsc hvdc transmission system and converter station. If the fault current is evaluated in per unit with the base value equal to the 3ph fault current at the corresponding fault location and without hvdc light connected, it turns out that the impact of the fault location seems to be insignificant.
The hvdc system is less expensive and has minimum losses. When dc poleground fault occurs, substantial over current generated due to the rapid decrease in the dc voltage. The total reliability of an hvdc system depends on the components in the line and at the stations. What is hvdc high voltage direct current transmission. Under the same load and operation condition, the 1ph fault. Abstractmany power electronic applications use harmonic filters to filter out harmonics generated by the conversion. High voltage direct current hvdc systems enable utilities to move more power further, interconnect grids, integrate renewables, and improve network performance.
The main vulnerabilities of hvdc networks during dc side faults are. The development of modular multilevel converter mmc and the increased needs for long distance bulk power transmission using. This book presents the various aspects of hvdc technology in sufficient depth to a beginner. Figure 8 illustrates solidstate converter development for the two different types of converter technologies using thyristor valves and igbt valves. Vsc hvdc c t d ivsc hvdc converter design with fault blocking capability for ohlapplications n m macleod, c d barker, for ohl applications r s whitehouse, w liang. Pilot protection scheme for transmission line of a hybrid hvdc. Analysis of faults in multiterminal hvdc grid for definition of test requirements of hvdc circuit breakers nadew a.
This paper presents a new protection method for high voltage direct current hvdc system based on transient power. The risk on converter switches from overcurrent due to grid contribution to dc fault current during dc side faults, and inrush current during recovery without interruption as the dc link voltage builds up after the fault is cleared. The level of overcurrent required to trip must be set higher than vgp to avoid tripping this is mainly used to detect the ground faults, such as neutral faults. For multiterminal or meshed voltage source converter vsc high voltage direct current hvdc systems, high speed protection against dc faults is essential, as power electronic components cannot. Dcdc converters located at strategic locations, joining different dc. It transmits the power between the unsynchronized ac system. Protection system reliability in the presence of hvdc and ac. It can be seen as the merging of two independent asymmetric monopole systems.
The improvement in the hvdc network dc fault ridethrough capability is achieved by stopping grid contribution to the fault current, and minimization of the transient component due to discharge of the dc side capacitors. High voltage direct current transmission only active power flow is associated with hvdc. Protection of vscmultiterminal hvdc against dc faults. The second key technology is an hvdc grid protection system which will be developed. Pdf a new protection scheme for hvdc converters against dc. You need experts who know how to make that future work for you. General, dc reactor, voltage oscillations and valve dampers, current oscillations and anode dampers, dc line oscillations and line dampers, clear line faults and reenergizing the line.
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