1. Yang, J., Fletcher, J.E., O'Reilly, J., 2010. Multiterminal DC Wind Farm Collection Grid Internal Fault Analysis and Protection Design. Ieee Transactions on Power Delivery 25, 2308-2318.
Abstract:
The multiterminal dc wind farm is a promising topology with a voltage-source inverter (VSI) connection at the onshore grid. Voltage-source converters (VSCs) are robust to ac-side fault conditions. However, they are vulnerable to dc faults on the dc side of the converter. This paper analyzes dc faults, their transients, and the resulting protection issues. Overcurrent faults are analyzed in detail and provide an insight into protection system design. The radial wind farm topology with star or string connection is considered. The outcomes may be applicable for VSCs in the multi-VSC dc wind farm collection grid and VSC-based high-voltage direct current (HVDC) offshore transmission systems
2. Roy, D.S., Anil, A., Mohanta, D.K., Panda, A.K., 2010. Well-being Analysis of Safety Critical Software: A Case Study for Computer Relaying. Electric Power Components and Systems 38, 1299-1316.
Abstract:
Assessment of software reliability has emerged as an area of utmost importance in recent times with the proliferation of software-based systems. Conventional software reliability assessment is done by applying software models that incorporate the unfortunate drawback of requiring previous failure data to formulate the model based on statistical methodologies. But highly dependable software systems used for safety-critical applications, such as computer relays for power system transmission line protection, produce little failure data. This article presents a methodology using statistics of extremes to embark upon software success estimation. The estimate so obtained is an indicator analogous to the conventional reliability index. This estimated reliability is further employed for assessing software's health more effectively by means of well-being analysis. The most significant contribution of this article is to compute the software well-being indices for healthy, marginal, and risky states. A case study for software used in computer relaying of power system transmission line protection validates the efficacy of the proposed methodology, especially for safety-critical applications
3. Moravej, Z., Abdoos, A.A., Sanaye-Pasand, M., 2010. A New Approach Based on S-transform for Discrimination and Classification of Inrush Current from Internal Fault Currents Using Probabilistic Neural Network. Electric Power Components and Systems 38, 1194-1210.
Abstract:
This article presents a new approach for differential protection of power transformers. The proposed method uses S-transform and a probabilistic neural network to discriminate internal faults from inrush current. S-transform is utilized to extract some useful features of non-stationary signal analysis, giving the information of transient currents both in time and frequency domains. The features extracted using S-transform are applied to train probabilistic neural network classifiers. This approach has been realized through two different stages. In the first stage, discrimination of inrush current and fault current has been done; in the second stage, different types of fault current will be recognized in four steps. The performance of this algorithm is demonstrated by simulation of different faults and switching conditions on a power transformer using PSCAD/EMTDC software (Manitoba HVDC Research Center, Winnipeg, Manitoba, Canada). The simulation results show that the combination of S-transform and a probabilistic neural network can effectively detect inrush current from fault currents and that it can also classify the fault currents with high accuracy and speed, even in a noisy environment
4. Mitolo, M., Sutherland, P.E., Natarajan, R., 2010. Effects of High Fault Currents on Ground Grid Design. Ieee Transactions on Industry Applications 46, 1118-1124.
Abstract:
Due to increased load demands and reduced incentives to build new transmission lines, energy companies are increasing power flows on the existing transmission assets, which will increase the fault current levels (for both three-phase and phase-to-ground faults) throughout the power system. New generation sources to be added at the transmission and distribution network will increase fault current intensities. It is crucial for the users of industrial facilities to be aware of increased ground-fault current magnitude at the service entrance and of the actual condition of the grid. The protection that ground grids provide against step and touch potentials is only good up to the expected level and duration of ground-fault currents, as originally communicated by the electric utility in the design phase. In addition, thermal and mechanical stresses to the customer's ground grid and ground grid connections can increase the grid's resistance to ground and, at the same time, fault potentials. In order to prevent these problems from occurring, a ground grid assessment, utilizing field and utility updated data, should be carried out on a regular basis. This paper will illustrate a European Committee for Electrotechnical Standardization (CENELEC) approach to ground grid design, aimed to maximize the electrical safety under ground fault. In addition, case studies will be included, showing how high fault currents have damaged ground grids and what repairs are possible
5. Suonan, J., Gao, S.P., Song, G.B., Jiao, Z.B., Kang, X.N., 2010. A Novel Fault-Location Method for HVDC Transmission Lines. Ieee Transactions on Power Delivery 25, 1203-1209.
Abstract:
This paper presents a method for locating faults on HVDC transmission lines using two terminal data. Different from those based on the traveling wave principle, the new fault-location algorithm can use any section of the postfault data to locate faults. The proposed method is developed based on the distributed parameter line model in which the voltage distribution over the line can be obtained from the voltage and current measurements at both terminals and point where fault occurs can be identified from the calculated voltage distribution. The fault-location algorithm is performed in time domain and thus a short data window is sufficient for it to achieve satisfactory accuracy in practice. The proposed algorithm is simulated using data of the frequency-dependent line model in EMTDC and data of an existing HVDC line as well. The simulations have shown that this method is valid and is capable of locating the faults occurring on HVDC transmission lines quickly and accurately
6. Ramtharan, G., Arulampalam, A., Ekanayake, J.B., Hughes, F.M., Jenkins, N., 2009. Fault ride through of fully rated converter wind turbines with AC and DC transmission systems. Iet Renewable Power Generation 3, 426-438.
Abstract:
Fault ride through of fully rated converter wind turbines in an offshore wind farm connected to onshore network via either high voltage AC (HVAC) or high voltage DC (HVDC) transmission is described. Control of the generators and the grid side converters is shown using vector control techniques. A de-loading scheme was used to protect the wind turbine DC link capacitors from over voltage. How de-loading of each generator aids the fault ride through of the wind farm connected through HVAC transmission is demonstrated. The voltage recovery of the AC network during the fault was enhanced by increasing the reactive power current of the wind turbine grid side converter. A practical fault ride through protection scheme for a wind farm connected through an HVDC link is to employ a chopper circuit on the HVDC link. Two alternatives to this approach are also discussed. The first involves de-loading the wind farm on detection of the fault, which requires communication of the fault condition to each wind turbine of the wind farm. The second scheme avoids this complex communication requirement by transferring the fault condition via control of the HVDC link to the offshore converter. The fault performances of the three schemes are simulated and the results were used to assess their respective capabilities
7. Liu, X., Osman, A.H., Malik, O.P., 2009. Hybrid Traveling Wave/Boundary Protection for Monopolar HVDC Line (vol 24, pg 569, 2009). Ieee Transactions on Power Delivery 24, 1750.
8. Liu, X.L., Osman, A.H., Malik, O.P., 2009. Hybrid Traveling Wave/Boundary Protection for Monopolar HVDC Line. Ieee Transactions on Power Delivery 24, 569-578.
Abstract:
A novel hybrid protection algorithm, based on traveling wave protection principle and boundary protection principle for a monopolar HVDC line is proposed. Stationary wavelet transform (SWT) is adopted in the traveling wave protection to process the do signal and then wavelet modulus maxima are used to further represent the useful traveling wave signal. The boundary protection principle based on SWT is used jointly with traveling wave protection to distinguish internal faults from external faults. The effect of border distortion, noise, high-ground fault resistance, close-up faults, transients caused by lightning strokes and different do line terminations are considered in the paper
9. Cao, J., Davidson, C., Moulson, S., 2007. Dynamic modelling of saturable reactor for HVDC applications. Iet Science Measurement & Technology 1, 138-144.
Abstract:
Experimental development of dynamic models for the saturable reactor for HVDC applications was made by taking account of the effects of the eddy-current, the air gap, and the nonlinear magnetisation of the cores of the 3% grain-oriented silicon steels used. The experimentally developed models were confirmed by comparing them to measurements with regard to step current, rate of change of the reactor current, and the current reversal as a result of the oscillations between the storage capacitance and the equivalent inductance of the saturable reactor. The magnetising inductances and the rules for approaching saturation of the cores were determined from actual static magnetisation curves, corrected according to the core geometry and the size of the air gaps used. The linear relationships between the mean magnetic polarisations and the eddy-current resistance factors, which correspond to the eddy-current resistance for a reactor with a 1-turn exciting coil and a unit core cross-sectional area-to-magnetic path length ratio, were established using a circuit representing the capacitance discharging in typical HVDC applications. The work presented simplifies the optimisation process, which aims to minimise the reactor cost and losses, but without compromising the safe protection of the semiconductors for HVDC applications
10. Tang, L.X., Ooi, B.T., 2007. Locating and isolating DC faults in multi-terminal DC systems. Ieee Transactions on Power Delivery 22, 1877-1884.
Abstract:
A VSC-MTDC (multi-terminal dc) system consists of Voltage-Source Converters (VSCs) connected to a dc network at their dc terminals. The MTDC is most vulnerable to a dc fault which paralyses all the VSCs until the dc fault is cleared. As dc circuit breakers are expensive, this paper proposes a solution based on extinguishing the dc fault current by opening all the ac-circuit breakers (ac-CBs) which the VSCs are already equipped with on the ac-sides. However, it is necessary to identify which dc line is the faulted line (in case it is a permanent fault) so that it can be isolated by fast dc switches (which are much more economical than the dc circuit breakers), prior to restoring the MTDC system by re-closing all the ac-CBs. This paper presents the handshaking method, which locates and isolates the faulted dc line and restores the MTDC without telecommunication
11. Faruque, M.O., Dinavahi, V., Santoso, S., Adapa, R., 2005. Review of electromagnetic transient models for non-VSC FACTS - IEEE working group on dynamic performance and modeling of HVDC and power electronics for transmission systems. Ieee Transactions on Power Delivery 20, 1065-1079.
Abstract:
This paper documents electromagnetic transient simulation models for conventional flexible AC transmission systems (FACTS) that do not employ voltage-sourced converter (VSC) technology. The FACTS controllers included in this document are classified into four categories: (1) shunt controllers (2) series controllers (3) combined shunt and series controllers (4) auxiliary controllers. Modeling techniques of these controllers are reviewed and the key aspects of each model are summarized. A comprehensive list of references is also included in this paper to provide further detailed information to the readers
12. Bolduc, L., Granger, M., Pare, G., Saintonge, J., Brophy, L., 2005. Development of a DC current-blocking device for transformer neutrals. Ieee Transactions on Power Delivery 20, 163-168.
Abstract:
In the early 1990s, Hydro-Quebec undertook a joint project with GE to develop and commission a dc current-blocking series capacitor for the transmission lines forming part of its main power system in the area surrounding the grounding electrode of the Radisson HVdc substation. The aim of this project was to minimize the harmful effects of dc current flowing through the main network during the ground-return operating mode of the Radisson-Sandy Pond multiterminal HVdc link. With a view to having available technology applicable anywhere in the network, TransEnergie and IREQ, two divisions of Hydro-Quebec, later took part in the development of a dc current-blocking device that could be installed in transformer neutrals. This work was undertaken not only with immediate needs in mind but also to solve specific problems that could appear sporadically at different network locations. Tests on a prototype of the new blocking device were performed in the High Power Laboratory at IREQ, followed by tests on the preproduction unit, in accordance with the specified requirements. The neutral dc current-blocking device (NI BD) was then installed at a regional substation for a one-year operating period to verify its immunity under normal network events and switching conditions. During this period, no disruption to the smooth operation of the substation or protection of the ac system occurred. The NCBD operated correctly and suffered no fault or unsolicited operation
13. Snider, L.A., Su, H.T., Chan, K.W., Van Que, D., 2003. Development of a broadband real-time fully-digital simulator for the study and control of large power systems. Mathematics and Computers in Simulation 63, 137-149.
Abstract:
While transient stability (TST) programs can represent very large systems, they are unable to model power electronic devices in detail since they use relatively large time steps and balanced representation of the network. Electromagnetic transients (EMT) simulators, on the other hand, can model relatively small systems in detail using small time steps. By interfacing both simulation tools, it will be possible to develop a broadband simulator capable of modeling large systems, but including detailed representation where required. The simulator would provide for studies ranging from fast transient to transient, dynamic, and voltage stability, with applications including closed-loop protection and control studies, as well as on-line dynamic security assessment (DSA). In this paper, we present the latest development work related to the realization of a broadband fully-digital simulator, which would be capable of meeting the challenge obtaining real-time solutions of very large networks using sufficiently small integration time steps such that power electronic devices (FACTS or HVDC) could be modeled at the device level with sufficient time resolution. (C) 2003 Published by Elsevier B.V. on behalf of IMACS
14. Hammons, T.J., 2003. Power cables in the twenty-first century. Electric Power Components and Systems 31, 967-994.
Abstract:
This paper presents a variety of Viewpoints from engineers within the power cable industry as to how current trends in the cable industry will influence future cable designs, particularly With polymeric insulation, lapped dielectrics, and improved diagnostic techniques. The use of high-temperature superconductors and designer polymers as well as the possible availability of conducting polymeric materials is also considered. The paper first reviews how the design of distribution cables has differed historically around the world, the major differences being allied to the systems. Designs largely have been divided into two main categories: those countries following U.K. and European practices, and those having adopted the U.S. system design. However, these differences, such as the use of three-phase cables in the U.K. as opposed to single-phase cables in the U.S., are not so obvious nowadays. Installation practices are becoming rather more standardized, such as the use of ducts, directional drilling, etc. The predominant primary insulation is cross-linked polyethylene (including tree-retardant XLPE), which is used all around the world. Some constructional differences such as the "dry" and "wet" designs persist. The paper then discusses cables from the mid-twentieth century projected into the twenty-first century. Highlighted are the opportunities that will present themselves in the twenty-first century: fluid-filled cables, XLPE cables, intelligent cables, and designer polymers that optimize performance and economic advantages of buried cables. It then focuses on economic trends, power generation trends, lower-cost underground systems, overhead line/underground cables, and materials and environmental trends including use of high-temperature conductors to up-rate overhead circuits. The trend will be toward greater security and utilization using on-line diagnostics, greater circuit diversity due to distributed generation and lower cost cable systems, and extensive use of polymeric materials having low environmental impact. A futuristic view of energy cables in the year 2050 is presented. Discussed are the elements of the "info-energy cable, " the advantages of the cable technology, and the advantages for the network configuration. A realistic view of tendencies in cable systems technology over the next decade is outlined. Also discussed is choice of cable for subsea power links: choice of cable design that exists for subsea power links, the merits of the various designs, installation of submarine cables, protection of submarine cables, new challenges in HVdc submarine cable systems, and future developments. The manufacture and installation of long continuous lengths of subsea power cable is discussed with reference to some key installations. The paper goes on to examine the Kontex HVdc link between Denmark and Germany. The cable link has been in commercial operation since 1996, and with a total length of 172 km and a transmission capacity of 600 MW at 400 kV is still unique worldwide. Details of the link together with its installation and commissioning are explained. Gas-insulated transmission lines are also discussed together with whether they are ready for real-world transmission systems
15. Hammons, T.J., 2002. Power generation in Asia to the year 2030: Environmental effect and strategy. Electric Power Components and Systems 30, 277-300.
Abstract:
This paper discusses reduction in specific CO2 emissions, industry efforts to promote use of natural gas, expanded nuclear generation, and research and development (R&D) works on improving efficiency of fossil plants. It also discusses feasibility of HVdc interconnected power systems for environmental protection, development of hydropower, and specific possible developments in Siberia and Rus;sia to the year 2030. The paper first discusses the main features of Asia's power sector. It examines how Asia will account for half of global generation expansion, where most of this expansion will be dominated by coal-firing power stations. It examines power in Japan: measures for environmental issues and related R&D. A reduction in specific CO2 emissions (kg-C/kWh) exceeding 30% has been achieved over the past 20 years as a result of expanded use of nuclear power generation and industry efforts to promote the use of liquefied natural gas. Discussed is Japan's target for CO2 reduction in the year 2010 of 6% below the level of 1990. The paper goes on to focus on prospects for development of power generation in East Russia. Current state of generating capacity of East Russia, prerequisites for prospective power development, and prospects for development are examined. Finally, future electric power development in China is reviewed. A feasibility study for interconnection of the eastern area of the Eurasian continent for around the year 2020 is then discussed
16. Tanabe, S., Kobayashi, S., Sampei, M., 2000. Study on overvoltage protection in HVDC LTT valve. Ieee Transactions on Power Delivery 15, 545-550.
Abstract:
The light-triggered thyristor (LTT), which can be directly fired by light, does not need gate electronics on the high-voltage side and is thus anear-ideal semiconductor device for a HVDC valve,In providing an overvoltage protection for LTT without losing its advantage of simple circuits associated with the thyristor, the overvoltage protection system adopted to the conventional electrically triggered thyristor is not necessarily appropriate. We have shown that high-speed protective gate pulses generated from the valve base electronics together with the valve arrester are sufficient for the LTT valve overvoltage protection. The adequacy of this protection strategy is demonstrated by factory type tests and also excel lent service experiences
17. Takasaki, M., Gibo, N., Takenaka, K., Hayashi, T., Konishi, H., Tanaka, S., Ito, H., 2000. Control and protection scheme of HVDC system with self-commutated converter in system fault conditions. Electrical Engineering in Japan 132, 6-18.
Abstract:
For extending self-commutated converter application to future trunk power systems, it is important to develop a stable operation scheme as well as to realize substantial cost reduction through coordinated system and control design. Suppression controls of converter overcurrent and de overvoltage in various system fault conditions are essential in order to ensure stable operation and cost reduction of HVDC systems with voltage source type self-commutated converters. Converter control and protection schemes which include such suppression controls have been developed, employing CRIEPI's ac/dc Power System Simulator test and EMTP analysis. This paper first discusses the cause of converter overcurrent at ac system faults, considering the effect of PWM pulse number and converter control speed. Continued operation has been achieved by adding a new overcurrent suppression scheme to the converter control. In the case of a de line grounding fault, the selection of the grounding circuit constant and the adoption of a high-speed converter control practically ensure the reduction of de overvoltage while suppressing converter overcurrent. The converter block and restart sequence after a de fault, which is coordinated with de circuit breaker operation, enables stable recovery of HVDC transmission as fast as the usual line-commutated HVDC system. (C) 2000 Scripts Technica
18. Olsen, S.K., Tonnesen, O., Ostergaard, J., 1999. Power applications for superconducting cables in Denmark. Ieee Transactions on Applied Superconductivity 9, 1285-1288.
Abstract:
In Denmark a growing concern for environmental protection has lead to wishes that the number of overhead lines is reduced as much as possible and that the energy supply should be shifted to renewable energy sources, e.g. windmills. Superconducting cables represent an interesting alternative to conventional cables, as they have other characteristics than conventional cables and will be able to transmit two or more times the current. Superconducting cables are especially interesting as a target for replacing overhead lines. Superconducting cables in the overall network are of interest in cases such as transmission of energy into cities and through areas of special beauty. The planned large groups of off-shore windmills-in Denmark generating up to 400 MVA or more will be an obvious case for the application of superconducting AC or DC cables. These opportunities can be combined with other new technologies such as high voltage DC (HVDC) based on isolated gate bipolar transistors (IGBTs). The network needed in a system with a substantial wind power generation has to be quite stiff in order to handle energy fluctuations. Such a network may be possible, e.g. using superconducting cables
19. Hu, Y., McLaren, P.G., Gole, A.M., Fedirchuk, D.J., Castro, A., 1999. Self-excitation operating constraint for generators connected to DC lines. Ieee Transactions on Power Systems 14, 1003-1009.
Abstract:
In a generating station linked to a main system through an HVDC transmission system, a load rejection of the HVDC line may cause generators in the station to become self-excited, resulting in a severe system overvoltage. It may also cause damage to generator exciters if negative current is not allowed to flow in the exciter. This paper derives the self-excitation operating constraint for generators operating in such a system. Results show that a self-excitation operating constraint greatly reduces the operating zone of a generator in such a station. However, this operating constraint can be effectively improved by self-excitation protection systems to remove surplus AC filter capacitive VARs
20. Ruff, M., Schulze, H.J., Kellner, U., 1999. Progress in the development of an 8-kV light-triggered thyristor with integrated protection functions. Ieee Transactions on Electron Devices 46, 1768-1774.
Abstract:
Light-triggered 8-kV thyristors with an integrated breakover diode were fabricated. The adjustment of the breakdown voltage of the breakover diode (BOD) is realized by a well-defined curvature of the junction between the D-base and the n-base, A multiple amplifying gate structure, together with an integrated turn-on curl ent limiting resistor, guarantees a safe turn-on behavior in the case of overvoltage triggering as well as during light triggering. These thyristors have successfully been put into service at the Celilo Converter Station of the Pacific Northwest-Southwest HVDC Intertie by Bonneville Power Administration in Portland/Oregon/USA. There, a mercury are valve was replaced by a valve containing these light triggered thyristors with integrated overvoltage protection. In a further development, the amplifying gate structure was optimized in order to simplify the fabrication process and to maintain the high light sensitivity while obtaining a higher dV/dt and a higher dI/dt capability, This was realized by shrinking the optical gate, by carefully adjusting the triggering sensitivity of the amplifying gates and by widening of the turn-on current limiting thyristor, With these measures, Initial investigations regarding the integration of a forward recovery protection were also performed
21. Vittal, V., Kliemann, W., Ni, Y.X., Chapman, D.G., Silk, A.D., Sobajic, D.J., 1998. Determination of generator groupings for an islanding scheme in the Manitoba Hydro system using the method of normal forms. Ieee Transactions on Power Systems 13, 1345-1351.
Abstract:
This paper deals with the application of the method of normal forms [1-5] in the analysis of a specific aspect of system dynamic behavior in the Manitoba Hydro system. Following a major loss of transmission capacity on the Manitoba Hydro HVDC system (Nelson River system), and the subsequent operation of protection systems, there is a major deficit of generation in the remaining system, comprising Manitoba and Saskatchewan. The method of normal forms is applied to determine the natural groupings which are formed by the machines in Manitoba Hydro due to nonlinear interaction. This grouping then provides a basis for developing a systematic procedure to island the remaining system
22. Gole, A.M., Nayak, O.B., Sidhu, T.S., Sachdev, M.S., 1996. A graphical electromagnetic simulation laboratory for power systems engineering programs. Ieee Transactions on Power Systems 11, 599-606.
Abstract: The recent availability of Electromagnetic Transient Programs with graphical front ends now makes it possible to put together models for circuits and systems in a manner similar to the connection of components in a laboratory. In the past, the non-graphical EMT Programs required considerable expertise in their use and thus distracted the students into the details of simulation. The introduction of a graphical simulation based laboratory into Undergraduate and Graduate Engineering Programs is presented, based on the PSCAD/EMTDC program, The philosophy behind the design of suitable example cases is presented within the framework of an Undergraduate Power Electronics Course, an HVdc Transmission Course and a course on Power System Protection
23. Haddad, A., Naylor, P., Tong, Y.K., Marley, W.A., Metwally, I.A., German, D.M., Waters, R.T., 1995. Direct Voltage and Trapped Charge Effects on the Protective Characteristic of Zno Surge Arresters. Iee Proceedings-Science Measurement and Technology 142, 442-448.
Abstract:
In AC power systems, under normal service conditions, surge arresters on isolated lines and cables can experience a direct voltage stress arising from trapped charges. If this is followed on reconnecting by switching surges of reverse polarity, it can impose severe response requirements on the arresters. High-amplitude voltage reversal can also arise from restriking transients in circuit breakers. Direct voltage working stress with superimposed surges is also clearly present in HVDC systems. Despite this expected combination of direct voltage with superimposed surges, no analogous tests are specified in the relevant standards. New laboratory tests have been performed on ZnO surge arrester elements and arresters, where impulse voltages have been applied with and without the presence of pre-existing direct voltage or simulated trapped charge. These tests have been analysed to ascertain the effect of prestressing on the current growth and protective characteristic of the arrester. In the laboratory source, the line/cable system has been represented by an equivalent capacitance which has been previously charged from a direct voltage. A single-stage capacitor bank is triggered to provide a lightning impulse test current. For a given level of peak discharge current, a higher level of residual voltage is found to appear across an arrester when the polarity of the applied impulse opposes that of the trapped charge voltage. This effect is especially marked in the peak residual voltage under this combination. Initial results suggest that the effect increases with decreasing protection voltage level
24. Takeda, H., Ayakawa, H., Tsumenaga, M., Sanpei, M., 1995. New Protection Method for Hvdc Lines Including Cables. Ieee Transactions on Power Delivery 10, 2035-2039.
Abstract:
For the third project of the Hokkaido-Honshu HVDC Link in Japan, called the HVDC Link III project (rated at 250 kVdc-1200 A-300 MW), we developed an HVDC transmission line protection method based on a new working principle that allows high-speed and highly sensitive detection of faults, enhancing reliability in the supply of electric power. In general, increasing the sensitivity of relays will lead to an increased likelihood of undesired operation whereas lowering the sensitivity will impair the responsiveness of the relays. Our proposed method meets these apparently incompatible requirements very well. Basically classified as a differential scheme, the HVDC transmission line protection method compensates for a charging and discharging current that flows through the line-to-ground capacitance at times of voltage variations caused by a line fault or by the operation of do power systems. The developed protection method is also characterized in that it uses current changes induced by voltage variations to restrain the operation of a relay. This configuration has made the proposed method far superior in responsiveness and sensitivity to the conventional protection method. A simulation using an EMTP (Electro-Magnetic Transients Program) was conducted on this method. Developed relay equipment embodying the new protection method was subjected to various verification tests, where this equipment was connected to a power system simulator, before being delivered to the BVDC Link III facility
25. Sekine, Y., Takahashi, K., Hayashi, T., 1995. Application of Power Electronics Technologies to the 21St-Century Bulk Power Transmission in Japan. International Journal of Electrical Power & Energy Systems 17, 181-193
.
Abstract:
The electric power industry in Japan is now carrying out a nation-wide research and development programme for the effective application of power electronics technologies to the bulk transmission network and interconnected power systems for the 21st century. The programme will continue for eight years funded by ten power utilities and subsidy fi om the national government. The research and development programme specifically consists of the following three study projects: AC high-voltage/large-current transmission (feasibility study on enhancement measures for AC transmission capability, and verification test of their effectiveness using a power system simulator); multiterminal HVDC transmission (feasibility study on multiterminal HVDC transmission, and development and verification test of a prototype control/protection device), high performance AC/DC converter (development of a partial model for a 300 MW self-commutated converter, and field test of the developed partial model)
26. Maharsi, Y., Do, V.Q., Sood, V.K., Casoria, S., Belanger, J., 1995. Hvdc Control-System Based on Parallel Digital Signal Processors. Ieee Transactions on Power Systems 10, 995-1002.
Abstract:
A numerical HVDC control system operating In real time has been developed for a simulator to be used for operator training. The control system, implemented with digital signal processors (DSPs), consists of typical HVDC control functions such as the synchronizing unit, the regulation unit, the protection unit, the firing unit, the tap changer and the reactive power regulation unit. Results from, the steady-state and the transient performance validation tests carried out on the IREQ power system simulator are provided
27. Zhao, Z., Iravani, M.R., 1994. Application of Gto Voltage-Source Inverter in A Hybrid Hvdc Link. Ieee Transactions on Power Delivery 9, 369-375.
Abstract:
This paper investigates the application of a GTO voltage source inverter in a two-terminal HVdc link, which is fed at the sending end by a line-commutated rectifier. This type of HVdc link may be applied when power transfer is predominantly unidirectional, especially to a weak ac system. The investigations are based on analytical studies and digital time-domain simulations with the Electro-Magnetic Transient program for DC systems (EMTDC). Control method and protection requirements are studied, together with dynamic behavior of the system following disturbances, e.g. de fault, ac fault, start-up etc. The studies are aimed at exhibiting the technical feasibility of the proposed HVdc scheme. Need for further studies is pointed out when necessary
28. Zhao, Z., Iravani, M.R., 1994. Application of Gto Voltage-Source Inverter for Tapping Hvdc Power. Iee Proceedings-Generation Transmission and Distribution 141, 19-26.
Abstract:
The application of a 12-pulse-GTO voltage-source inverter (VSI) for tapping a small amount of HVDC power (10-15%) is investigated. The control strategy for a parallel multiterminal DC system is briefly reviewed. A comparison of VSI and line-commutated inverter characteristics indicates that GTO VSI offers some technical advantages for tapping applications. To confirm this, detailed digital time-domain simulations based on the Electromagnetic Transients Program for DC Systems are conducted. The simulated responses of the HVDC system embedding the GTO VSI tap under various planned and unplanned disturbances, evidence the technical feasibility of a small parallel tap of GTO VSI. In addition, control strategy and protection requirements are identified for the proposed HVDC tap
29. Whitehouse, R.S., 1993. Protecting A Hvdc Link Against Accidental Isolation from Its Receiving Ac System. Ieee Transactions on Power Delivery 8, 1586-1590.
Abstract:
When an HVdc scheme is isolated from its receiving ac system, the inverter may continue to operate, generating its own ac bus voltages; this is defined here as islanding. If islanding is allowed to continue unrestricted, then main circuit components may in some conditions be damaged and it is therefore necessary to provide a suitable protection system. This paper outlines the protection scheme developed for the McNeill Back-to-Back HVdc link in Alberta, Canada, to prevent damage due to islanding while still permitting the link to automatically restart on reclosure of the isolating breaker Oscillograms showing the protection in operation on both the GEC ALSTHOM HVdc simulator and during tests carried out as part of the commissioning of the McNeill HVdc link are included [1]
30. Zhang, W.Y., Asplund, G., Aberg, A., Lemay, J., Jonsson, U., Loof, O., 1993. Active Dc Filter for Hvdc System - A Test Installation in the Konti-Skan Dc Link at Lindome Converter Station. Ieee Transactions on Power Delivery 8, 1599-1606.
Abstract:
The purpose of introducing active dc filters is to meet the more and more stringent requirement from power utilities on limiting telephone interference caused by harmonic currents from HVdc transmission lines, without unnecessarily increasing the cost of HVdc stations, An active dc filter installed in the Konti-Skan HVdc link is described. The active dc filter is connected at the bottom of an existing passive dc filter at the Lindome station. The active dc filter includes optic harmonic current measuring unit, control system, protection and supervision system, PWM power amplifier, high-frequency transformer, surge arrester, and coupling apparatuses. The active dc filter has small physical size and occupies small ground area. The performance of the active dc filter for eliminating the disturbing harmonics is excellent. To achieve comparable results by passive filters would require something like ten times more high voltage equipment
31. Thallam, R.S., 1991. Bibliography on Overvoltage Protection and Insulation Coordination of Hvdc Converter Stations, 1979-1989. Ieee Transactions on Power Delivery 6, 743-753.
Abstract:
This bibliography is a listing of references on the subject of overvoltage protection and insulation coordination of HVdc converter stations, for the years 1979 through 1989. References are sorted by year of publication, and alphabetically based on first author's name within each year. Each reference includes the title, author, abstract and publication information
32. Manohar, P., Chandrasekharaiah, H.S., 1991. Application of Zno Varistor Protection to Capacitors of Artificially Commutated Inverter in Mtdc System. Ieee Transactions on Power Systems 6, 356-363.
Abstract:
The dynamic analysis of a mesh type multiterminal HVDC (MTDC) transmission system including an artificially commutated inverter (ACI) with varistor protected series capacitors is carried out using digital simulation technique. The study shows that the varistor protection is feasible and improves the performance of normal rated inverters which connect weak ac systems. It reduces the magnitude of dynamic overvoltage and the peak direct current at the ACI during abnormal conditions resulting in a significantly improved dynamic performance of
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