Highly Efficient Solutions for Smart and Bulk Power Transmission of Green Energy. W. Breuer, D. Retzmann, K. Uecker. Siemens AG, Energy Sector

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1 Highly Efficient Solutions for Smart and Bulk Power Transmission of Green Energy W. Breuer, D. Retzmann, K. Uecker Siemens AG, Energy Sector 21 TH WORD ENERGY ONGRESS, Montreal, anada September 12-16, 2010 opyright Siemens AG All rights reserved. opyright Siemens AG All rights reserved. 1

2 Highly Efficient Solutions for Smart and Bulk Power Transmission of Green Energy W. Breuer, D. Retzmann*, K. Uecker Siemens AG, Energy Sector Erlangen, Germany ABSTRAT The electric power supply is essential for the survival of a society, like the blood in the body. ack of power brings about devastating consequences for daily life. However, deregulation and privatization are posing new challenges to the transmission systems. System elements are going to be loaded up to their thermal limits, and wide-area power trading with fast varying load patterns will contribute to an increasing congestion. In addition to this, the dramatic global climate developments call for changes in the way electricity is supplied. Environmental constraints, such as loss minimization and O 2 reduction, will play an increasingly important role. onsequently, we have to deal with an area of conflicts between reliability of supply, environmental sustainability as well as economic efficiency. The power grid of the future must be secure, cost-effective and environmentally compatible. The combination of these three tasks can be tackled with the help of ideas, intelligent solutions as well as innovative technologies. Innovative solutions with HVD (High-Voltage D) and FATS (Flexible A Transmission Systems) have the potential to cope with the new challenges. By means of Power Electronics, they provide features which are necessary to avoid technical problems in the power systems, they increase the transmission capacity and system stability very efficiently and help prevent cascading disturbances. KEY WORDS: Smart and Super Grid Technologies; HVD, FATS; Sustainability and Security of Power Supply; Increase in Transmission apacity; Solutions for Bulk Power Transmission; Reduction in Transmission osses; Enhanced Grid Access for Regenerative Energy Sources (RES) *dietmar.retzmann@siemens.com opyright Siemens AG All rights reserved. 2

3 1. INTRODUTION The availability of electric power is the crucial prerequisite for the survivability of a modern society and power grids are virtually its lifelines. Without power supply there are devastating consequences for daily life. However, deregulation and privatization are posing new challenges to the transmission systems. System elements are going to be loaded up to their thermal limits, and wide-area power trading with fast varying load patterns will contribute to an increasing congestion. In addition to this, the dramatic global climate developments call for changes in the way electricity is supplied. Environmental constraints, such as loss minimization and O 2 reduction, will play an increasingly important role. onsequently, we have to deal with an area of conflicts between reliability of supply, environmental sustainability as well as economic efficiency. The power grid of the future must be secure, costeffective and environmentally compatible. The combination of these three tasks can be tackled with the help of ideas, intelligent solutions as well as innovative technologies. The combination of these three tasks can be solved with the help of ideas, intelligent solutions as well as innovative technologies. Innovative solutions with HVD and FATS have the potential to cope with the new challenges. By means of Power Electronics, they provide features which are necessary to avoid technical problems in the power systems, they increase the transmission capacity and system stability very efficiently and help prevent cascading disturbances. The vision and enhancement strategy for the future electricity networks are, for example, depicted in the program for SmartGrids, which was developed within the European Technology Platform. Features of a future Smart Grid such as this can be outlined as follows [1]: Flexible: fulfilling customers needs whilst responding to the changes and challenges ahead Accessible: granting connection access to all network users, particularly for RES and high efficiency local generation with zero or low carbon emissions Reliable: assuring and improving security and quality of supply Economic: providing best value through innovation, efficient energy management and level playing field competition and regulation Smart Grids will help achieve a sustainable development. It is worthwhile mentioning that the Smart Grid vision is in the same way applicable to the system developments in other regions of the world. Smart Grids will help achieve a sustainable development. An increasingly liberalized market will encourage trading opportunities to be identified and developed. Smart Grids is a necessary response to the environmental, social and political demands placed on energy supply. inks will be strengthened across North and South America, East and West Europe, Africa and Asia, interconnecting countries where different but complementary renewable resources are to be found. For the interconnections, innovative solutions will be essential to avoid congestion and to improve stability. HVD provides the necessary features to avoid technical problems in the power systems. It also increases the transmission capacity and system stability very efficiently and helps prevent cascading disturbances. HVD can also be applied as a hybrid A-D solution in synchronous A systems either as a Back-to-Back for grid power flow control (elimination of congestion and loop flows) or as a long-distance point-to-point transmission. FATS technology encompasses systems for both parallel and series compensation. It rests upon the principle of reactive power elements, controlled by means of power electronics, which can increase the transmission capacity of long A lines or stabilize the voltage of selected grid nodes. Due to a high utilization degree of A power grids, the application of FATS technology will become an increasingly more interesting issue also in the case of meshed power systems, e.g. in Europe. HVD and FATS applications will consequently play an important role in the future development of power systems. This will result in efficient, low-loss A/D hybrid grids which will ensure better opyright Siemens AG All rights reserved. 3

4 controllability of the power flow and, in doing so, do their part in preventing domino effects in case of disturbances and blackouts. In what follows, the global trends in power markets and the prospects of system developments are depicted, and the outlook for Smart Grid technologies for environmental sustainability and system security is given. 2. SEURITY AND SUSTAINABIITY DUE TO POWER EETRONIS From the point of view of the design concept, the A grids are not configured as wide-area bulk power transmission systems. By way of example, the entral European Power Grid (E, former UTE) at a transmission voltage of 400 kv was originally based on the concept of a system which provides power generation near the loads and has additional links to support the adjacent grids in the case of disturbances or planned outages of individual generation units. In the course of deregulation and privatization of European power markets the idea of an All- European interconnected system came up, and in view of climate change, the issue of bulk power transmission of environmentally compatible energy completed the picture. However, prior to implementing this vision to the full extent, the grid concept must be adapted to these modified conditions. Now, the question is how renewable energies, wind power in particular, influence the grid in case of an outage. At 21:38, both ircuits of a 400 kv ine in the Northern German Grid were switched-off in order to allow a large Ship to pass the Ems River n-2! At around 22:10, the whole Europe was affected and UTE split into 3 Islands Source: UTE Final Report Fig. 1 - European Power System Disturbance on November 4, 2006 The prime example here is the massive outage experienced in the European grid on November 4, The events started in the evening around 9:30 pm, and were triggered by the deliberate disconnection of two 400 kv lines over the Ems river in order to let a large vessel pass. Due to this, a number of lines were overloaded which resulted in a domino effect typical of massive outages of this kind and ended up in the splitting of the UTE system (now E, entral Europe) into three areas at different frequencies. It was the over-frequency area which, in addition to the congestion provoked by the failed lines, suffered from an excessive electric power infeed from wind farms, which was exactly what an over-frequency area required the least at that time. This scenario is depicted in Figs It has highlighted the fact that ontinental Europe is already behaving to some extent as a single power system, but with a network not designed accordingly. Europe's power system (including its network infrastructure) has to be planned, built and operated for the consumers it will serve. opyright Siemens AG All rights reserved. 4

5 Identifying, planning and building this infrastructure in liberalized markets is an ongoing process that requires regular monitoring and coordination between market actors. Fig. 2 depicts separate parts of the E grid in load-dependent colors; the red color marks a significant overload resulting in high phase-angle differences, and the green one reflects a situation in which even more current can easily flow through. b) a) Source: 5. EES Slovenia & Information Session, 28 Nov Stuttgart, Germany Fig. 2 Voltage Phase-Angle Difference a) normal ondition & b) shortly before System Separation Fig. 3 The Solution: Transmission of Windmill Power by means of HVD from Area 2 to Area 1 and Area 3 opyright Siemens AG All rights reserved. 5

6 Should even far higher input from offshore wind farms into the northern German grid come into play in the future, as Fig. 3 suggests, the HVD technology could provide the best possibility to forward the power surplus from the low-load North directly to the Southern load centres of Germany or to the adjacent countries with higher power demand. This idea rests upon a well-known experience with hybrid grids in other countries, according to which the D point-to-point connection carries out an easy power transfer over large distances and the adjacent A grid is additionally supported by means of FATS. The most devoted users of this hybrid concept are India and hina, see Figs. 4 and 5. Further examples of projects (from Siemens) with integrated A/D systems in a number of countries are depicted in Fig. 4, right part. Fully integrated Adani HVD a private Investor goes ahead 960 km 2,500 MW km 2,500 MW Ballia-Bhiwadi Power Grid orporation of India td Further Examples of Projects with Integrated A/D Transmission: East-South Interconnector the D Energy Bridge 1,450 km ,500 MW ,000 MW Examples of Integrated A/D Systems ahora Bassa, Mozambique-South Africa, , 1920 MW, 533 kv, 1400 km Gezhouba-Shanghai, hina, 1989/1990, 1200 MW, 500 kv, 1040 km Tianshengqiao-Guangzhou, hina, 2000, 1800 MW, 500 kv, 960 km Guiguang I, hina, 2004, 3000 MW, 500 kv, 940 km Guiguang II, hina, 2007/2008, 3000 MW, 500 kv, 1230 km Neptune, New York, 2007, 660 MW, 500 kv, 105 km able Yunnan-Guangdong, 2009/2010, 5000 MW, 800 kv, 1420 km Trans Bay able, HVD PUS, San Francisco, 2010, 400 MW, 200 kv, 88 km able Xiangjiaba-Shanghai, 2010, 6400 MW, 800 kv, 2071 km Fig. 4 India: Three large HVDs at 500 kv of which Adani and Ballia-Bhiwadi are fully integrated into the A Grid Fig. 5 arge HVD Projects in Southern hina enable low-loss West-to-East Transmission opyright Siemens AG All rights reserved. 6

7 3. BENEFITS OF POWER EETRONIS FOR SYSTEM ENHANEMENT Power electronics is used in high-voltage systems for FATS as well as for HVD. HVD helps prevent bottlenecks and overloads in power grids by means of systematic power-flow control. The function of the HVD which is decisive for system security is that of an automatic firewall. This firewall function can prevent the spread of a disturbance, which occurs in the system, at all times; as soon as the disturbance has been cleared, power transmission can immediately be resumed. Moreover, the HVD technology allows for grid access of generation facilities on the basis of availabilitydependent regenerative energy sources, including large offshore wind farms, and, compared with the conventional A transmission, it boasts a significantly lower level of transmission losses on the way to the loads [2-4]. FATS technology was originally created to support weak A grids and to stabilize A transmission over very long distances. FATS technology encompasses systems for both parallel and series compensation. It rests upon the principle of reactive power elements, controlled by means of power electronics, which can reduce the transmission angle (increase in transmission capacity) of long A lines or stabilize the voltage of selected grid nodes to control load flow and to improve dynamic conditions. Moreover, FATS can help solve technical problems in the interconnected power systems. Examples of FATS controllers are: SV - Static VAR ompensator STATOM - Static Synchronous ompensator FS - Fixed Series ompensation TS/TPS - Thyristor ontrolled/protected Series ompensation S³ - Solid-State Series ompensator UPF - Unified Power Flow ontroller S - onvertible Static ompensator Rating of SVs can go up to 800 MVAr; the world s biggest FATS project with series compensation (TS/FS) is at Purnea and Gorakhpur in India at a total rating of 1.7 GVAr. In Fig. 6, the basic applications of HVD and FATS to solve system problems are explained. * Short-ircuit urrent imitation for connecting new Power Plants SV & HVD for Voltage ollapse Prevention oad Management by HVD The FATS & HVD Application Guide oad Displacement by Series ompensation * PTDF = Power Transfer Distribution Factor Fig. 6 Elimination of Bottlenecks in Transmission The Power Electronics Application The figure depicts separate lines in load-dependent colors; the red color marks a significant overload, and the green one reflects a situation in which even more current can easily flow through. For the sake opyright Siemens AG All rights reserved. 7

8 of a consistent load flow, the ideal solution would be to furnish the grid, which is entirely open for power trading, with yellow lines, which helps do away with the less loaded grey ones. It is needless to say that in the context of a complex, largely meshed grid without any additional measures to boost its efficiency, an optimal load-flow control such as this is not possible. Due to a high utilization degree of A power grids, the application of FATS technology will become an increasingly more interesting issue also in the case of large meshed power systems, e.g. in entral Europe. FATS and HVD applications will consequently play an important role in the future development of power systems. This will result in efficient, low-loss A/D hybrid grids which will ensure better controllability of the power flow and, in doing so, do their part in preventing domino effects in case of disturbances and blackouts. In Fig. 7, the configuration possibilities of HVD are depicted and Fig. 8 shows a comparison of the control features of HVD and FATS for interconnection of large systems. a) D supports A in Terms of Stability c) an be connected to long A ines b) c) a) Back-to-Back Solution b) HVD ong-distance Transmission c) Integration of HVD into the A System The Firewall for Blackout Prevention Fig. 7 HVD onfigurations a) G ~ oads ~ P FATS lassic FATS VS ~ oads G ~ G ~ oads b) G ~ = lassic or VS +/- P = oads G ~ a) FATS: Voltage / oad-flow ontrol (one Direction only) & POD b) HVD Back-to-Back or ong-distance Transmission: Voltage / Bidirectional Power-Flow ontrol, f-ontrol & POD Fig. 8 System Interconnections: ontrol Features of FATS and HVD opyright Siemens AG All rights reserved. 8

9 4. PROSPETS OF POWER SYSTEM DEVEOPMENTS Based on the previous evaluations, Figs. 9 and 10 show the stepwise interconnection of a number of grids by using A lines, D Back-to-Back systems, D long distance transmissions and FATS for strengthening the A lines. Micro Grid (autonomous) Smart Grid Super Grid G G S A A A G G A = ell Agent Storage S ell G + + = Generation Smart, controlled oads Virtual Power Plant A Power Transmission Division A G S D G A Bulk Power A/D Energy Highway Fig. 9: Prospects of Grid Developments System G System A System B System System D System E System F The Result: Step 3 Step 2 Step 1 arge arge System Interconnections, with with HVD and FATS HVD ong-distance D Transmission HVD B2B viaa ines High-Voltage A Transmission & FATS D is a Stability Booster and Firewall against Blackout A Super Grid Smart & Strong ountermeasures against large Blackouts Fig. 10: Hybrid System Interconnections Supergrid with HVD and FATS opyright Siemens AG All rights reserved. 9

10 These integrated hybrid A/D systems provide significant advantages in terms of technology, economics as well as system security. They reduce transmission costs and help bypass heavily loaded A systems. With these D and A Ultra High Power transmission technologies, the Smart Grid, consisting of a number of highly flexible Micro Grids will turn into a Super Grid with Bulk Power Energy Highways, fully suitable for a secure and sustainable access to huge renewable energy resources such as hydro, solar and wind, as indicated in Fig. 9. This approach is an important step in the direction of environmental sustainability of power supply: transmission technologies with HVD and FATS can effectively help reduce transmission losses and O 2 emissions. The state-of-the-art A and D technologies and solutions for Smart and Super Grids are depicted in the following sections. 5. TEHNOOGIES FOR SMART AND SUPER GRIDS The core or the workhorse of line-commutated HVD and FATS installations are high-power thyristors, triggered optically by means of laser technology or electrically depending on application. Thyristors can only switch on the current. The switching-off is carried out by the next current zero crossing itself. This is the reason why a thyristor converter is referred to as a line-commutated system. Should no line voltage be available on one side of an HVD system or in a FATS application, the system would no longer be functioning. An advantage of thyristor converters is their high loading capacity both during nominal and overload operation as well as in the event of contingency. onsequently, bulk-power systems at high transmission capacities of 5 to over 7 GW can be implemented with thyristors only. A further benefit consists in comparatively low station losses. The TPS technology mentioned before uses special-purpose thyristors capable of withstanding transient over-loading of up to approximately 110 ka. The strength, i.e. short-circuit power of the grid, is an important design criterion for the application of line-commutated HVD systems. If the grid is too weak, a thyristor-based HVD system must reduce its power or, under certain conditions, shut down completely in order to avoid system collapse resulting from repetitive commutation failures. In the case of weak grids, remedy is provided by FATS for grid support, i.e. a combination of the HVD and FATS as in the example of the SV Siems for the HVD project Baltic able [3]. Additionally, the problem can be tackled by means of self-commutated converters. Self-commutated converters make use of elements which can be switched off, mostly modular or press-pack high-power transistors, all of which, in their turn, consist of a number of separate elements, connected in parallel. In this way, a converter turns into an electronic generator. Self-commutated converters are normally furnished with a voltage-sourced D circuit. With its help a separate capacitor or a number of them keep the voltage constant (VS: Voltage-Sourced onverter), whereas a conventional thyristor-based HVD system keeps the source current constant (S: urrent-sourced onverter) by means of reactors. A detailed description of different VS solutions is given in [2], for example. A general advantage of the VS-based HVD systems consists in the fact that one of the power grids subject to coupling can be completely voltage-free or passive, for, with the help of the intact grid, the other one can be started again similar to a power plant. This black-start capability is particularly interesting for connecting large offshore wind farms off the coast of Germany. 5.1 Smart Grid Solutions with VS - Modular Multilevel onverters An innovative development known as the MM (Modular Multilevel onverter) technology is described in item [2], which is applied by Siemens as an HVD PUS for the HVD projects and as an SV PUS for FATS. This technology stands out due to its compact modular design and a new multilevel converter, which allows to generate an A system of a virtually ideal sinus waveform from D voltage in the voltage source by means of a great number of fine steps without any additional filters. The reactive power elements and filters of normally 50% of the active power, required in HVD lassic applications, can be done completely away with in this case, which helps reduce the footprint of an HVD station by approx. 40 %. VS technology is the preferred solution for Smart opyright Siemens AG All rights reserved. 10

11 Grid applications, whereas the lassic and Bulk Thyristor technology is the solution for Super Grids. An overview of the first MM HVD project with a 200 kv XPE D sea cable transmission is given in Fig. 11. The goal of this project was to eliminate bottlenecks in the overloaded alifornian grid: new power plants cannot be constructed in this densely populated area and there is no right-ofway for new lines or land cables. This is the reason why a D cable is laid through the bay, and the power flows through it by means of the HVD PUS technology in an environmentally compatible way. Transmission onstraints before TB 2010 = ~ = Transmission onstraints after TB Energy Exchange by Sea able No Increase in Short-ircuit Power P = 400 MW Q = +/ MVAr Elimination of Transmission Bottlenecks = ~ = Dynamic Voltage Support Fig. 11 The Trans Bay able project in the U.S., World s first VS HVD with MM Technology and +/- 200 kv XPE able Wind Farms: Veja Mate and Global Tech MW, located 125 km Offshore (Northwest of the Island of Borkum) The Siemens Wind Power Offshore Substation (WIPOS) is designed as a floating, selflifting Platform The Platform will be towed by Tugs to its Destination at Sea, where the Water is about 40 meters deep A large heavy-duty rane vessel is not needed to lift the Topside onto its Foundation The Modular Multilevel VS Technology (MM) reduces omplexity and therefore the Space required for Installation = ~ = 2013 Fig. 12 HVD PUS and WIPOS: BorWin 2, Germany World s biggest VS HVD with 800 MW opyright Siemens AG All rights reserved. 11

12 Siemens second HVD PUS project is the world s largest D Offshore installation BorWin 2 with a power transfer of 800 MW for Grid Access of wind energy (Fig. 12). The entire PUS system has a modular structure and can be flexibly configured, what simplifies its standardization, see Fig. 13. The converter modules are connected on the secondary side of a highvoltage coupling transformer (for simplification not shown in the figure) to build the HVD or the SV. Due to the MM configuration, there is almost no or, in the worst case, very small - need for A voltage filtering to achieve a clean voltage. The system configuration is very compact and normally occupies 50 % less space than a classic HVD or SV systems. Examples of projects with SV PUS and the configuration possibilities are shown in Fig. 14. onverter Arm PM 1 PM 1 PM 1 PM 2 PM 2 PM 2 Power Module with D apacitor PM n PM n PM n v v V d u d PM 1 PM 1 PM 1 PM 2 PM 2 PM 2 PM n PM n PM n Phase Unit ontrolled Voltage Sources ontrolled Voltage Sources Fig. 13 VS Technology with MM: SV PUS and HVD PUS (ref. to Text) onfiguration of Multilevel Voltage Sources for SV (left Side) and HVD (right Side) opyright Siemens AG All rights reserved. 12

13 SV PUS: 3 x PUS in parallel 132 kv / 13.9 kv a) SV PUS: 4 x PUS in parallel kv / 13.9 kv and ondon Array World s largest Offshore Wind Farm 630 MW & Upgrade up to 1 GW b) SV PUS: 2 x PUS M in parallel 220 kv / 11 kv Dynamic Voltage Support during and after A ine Faults (Voltage Dip ompensation) 2009 c) ontainerized Solutions: SV PUS S: +/- 25 MVAr SV PUS M: +/- 35 MVAr SV PUS : +/- 50 MVAr Open Rack Solution (Building): SV PUS : +/-100 MVAr SV PUS Hybrid (Option): MSR (Mechanically Switched Reactors) MS (Mechanically Switched apacitors) Up to 4 parallel -Units: +/- 200 MVAr Fig. 14 A wide Range of Application Possibilities: a) Grid Access of Green Energy with SV PUS - Greater Gabbard and ondon Array, UK b) Power Quality in A Systems Kikiwa Project, South Island, New Zealand c) From ontainerized to Open Rack and Hybrid Solutions opyright Siemens AG All rights reserved. 13

14 The state-of-the-art highly flexible MM technology for HVD PUS and SV PUS makes it possible to easily comply with all the known voltage quality requirements (Grid odes) for grid access of wind farms as well as for transmission systems. In addition to this, the MM PUS technology is used for traction supply with Static Frequency onverters (SF) and for industrial applications. The field of synergies and applications is therefore boundless. 5.2 Super Grid Solutions with FATS and HVD - lassic and Bulk The progressive worldwide urbanization, as well as the trend towards megacities with more than 10 million inhabitants, poses new challenges on the power transmission systems. In every country of the world the economic pulses coming from cities provide more than half of the gross domestic product of the respective country, according to UN-statistics. One of the most important factors for the economic dynamics of megacities is an effective infrastructure. It goes without saying that the basis for this infrastructure is constituted by a reliable and efficient power supply. An important development in the power supply of megacities is the outsourcing of power generation to close or more distant surrounding regions. That is, transmission networks and distribution systems are forced to interconnect increasingly longer distances. Furthermore, efficiency and reliability of supply play an important role in every planning, particularly in the face of increasing energy prices and almost incalculable safety risks during power blackouts. Such an example is shown in Fig. 15. In India, for the increasing power demands of the area of the Megacity New Delhi, the world s biggest FATS project with series compensation (TS/FS) was installed at Purnea and Gorakhpur with a total rating of 2 x 1.7 GVAr, ref. to the figure. This project provides clean and cheap hydro power from Bhutan over long distances. The systems at Purnea and Gorakhpur Substations use a combination of FS and TS. TS is used if fast control of the line impedance is required, for load-flow control and for damping of power oscillations and FS is an economic way to reduce the transmission angle over the line and to increase the transmission capacity. Fig. 15 Tala TS Project: Bulk Hydro Power from Bhutan to Delhi Area World s largest FATS for Series ompensation The most devoted user of the Bulk Power D transmission concept is hina. The UHV HVD systems at 800 kv require the most state-of-the-art converter technology. The separate components of this kind of installations boast impressive design and dimensions owing to the required insulation clearance distances. hina requires this HVD technology to construct a number of high-power D energy highways, superimposed to the A grid, in order to transmit electric power from huge hydro power plants in the center of the country to the load centers located as far as 2,000 to 3,000 km away with as little losses as possible. Fig. 16 depicts an example of the 3,000 MW HVD project Gui- Guang I in Southern hina. opyright Siemens AG All rights reserved. 14

15 Fig. 16 HVD projects in Southern hina enable low-oss West-to-East Transmission of Hydropower-based electrical Energy produced in the ountry s Interior to coastal oad enters (Example of ong-distance Transmission Gui-Guang I) The next generation HVD project is the UHV D Yunnan-Guangdong at a transfer capacity of 5 GW (see Figs.17-18). Siemens and the utility hina Southern Power Grid succeeded to put pole 1 of this world s first 800 kv HVD into operation in December 2009 and pole 2 in June ,418 km 5,000 MW +/- 800 kv D ommercial Operation: 2009 Pole Pole 2 Siemens the eader in Bulk Power UHV D Transmission Technology Yunnan-Guangdong Reduction in O 2 versus local Power Supply with Energy-Mix 32.9 m tons p.a. by using Hydro Energyand HVD for Transmission Fig. 17 Yunnan-Guangdong: World s first 800 kv UHV D in hina Southern Power Grid The Yunnan-Guangdong project helps save around 33 m tons O 2 in comparison with local power generation, which, in view of the current energy mix in hina, would be connected with a relatively high carbon amount, ref. to Fig. 17. Figs give views of the huge dimensions of the HVD stations and the equipment. opyright Siemens AG All rights reserved. 15

16 Fig. 18 Yunnan-Guangdong: Example of Sending Station huxiong; from 3D Model to Reality Fig. 20 shows pictures of the system inauguration of Pole 1 of this big project, which in fact is a kickoff for the D Super Grid Developments, worldwide. There are many benefits when using UHV D: at a voltage of +/- 800 kv, the line losses drop by approx. 60 % compared with the present standard of 500 kv D at the same power for 660 kv, the loss reduction is 43 %. When comparing transmission losses of A and D, it becomes apparent that the latter typically has 30 to 40 % less losses. The converter losses (i.e. those of both converter stations, incl. transformers, valve cooling and other equipment) amount to 1.3 to 1.5 % of the rated power only (depending on design). The second 800 kv HVD project Xiangjiaba-Shanghai of State Grid orporation of hina (ref. to Fig. 21a), which also involves Siemens as well as ABB and hinese partners, boasts significantly high yearly O 2 savings of over 40 m tons thanks to very high hydro power transmission capacity of 6.4 GW. This currently world s biggest UHV D started bipolar operation in June Siemens and its hinese partners delivered all HVD transformers and thyristor valves with new 6-inch thyristors for the sending station Fulong, one year ahead of schedule. These are the biggest HVD transformers and power converters ever built. Further UHV D projects at a transmission capacity of up to 9 GW are being planned in hina, see Fig. 21b). A total number of 35 Bulk Power HVD projects are planned for the time period 2010 to 2020, and the total transmission capacity will amount to 217 GW (as currently planned). A great number of these UHV D projects in hina is meant for power transmission from hydro power plants situated in the middle of the country to the distant load centers. opyright Siemens AG All rights reserved. 16

17 800 kv D 800 kv D 2 x 400 kv D 800 kv D Fig kv UHV D Yunnan-Guangdong: View of the Bipolar Valve Halls Two 400 kv Systems in series to build 800 kv (upper Part) Inside the 800 kv Valve Hall the onverter System (Middle Part) Bipolar D ine - uniting the single +/- ines coming out of the Station (ower Part) opyright Siemens AG All rights reserved. 17

18 2,500 MW 2,500 MW Fig. 20 Yunnan-Guangdong UHV D Inauguration on Dec. 28, 2009: elebration of Pole 1 successful ommissioning and Start of full Bipolar Operation in June 2010 a) Siemens received an Order for the Fulong onverter Station HVD Transformers & Thyristor Valves with new 6-inch Thyristors eshan Sichuan Power Grid hongqing Xiangjiaba-Shanghai Wuhan Shanghai Nanhui Xiangjiaba Xiluodu left Xiangjiaba Xiluodu Xiluodu right left Xiluodu right 970km Xiluodu-Zhuzhou Xiluodu-Zhexi hangsha Zhuzhou 1728km Zhexi 2,071 km 6,400 MW +/- 800 kv D ommercial Operation: 2010 b) Guangdong Reduction in O 2 versus local Power Supply with Energy-Mix 41 m tons p.a. by using Hydro Energy and HVD for Transmission 1. Yunnan Guangdong 800 kv, 5000 MW, 2009/10 2. Xiangjiaba Shanghai 800 kv, 6400 MW, Qinghai Tibet 500 kv, 1200 MW, Mongolia Tianjin 660 kv, 4000 MW, Russia iaoning 660 kv, 4000 MW, Nuozhadu Guangdong 800 kv, 5000 MW, Jingping Sunan 800 kv, 7200 MW, Xiluodu Guangdong 500 kv, 2 x 3200 MW, Humeng Tangshan 660 kv, 4000 MW, Ningdong Zhejiang 800 kv, 7200 MW, Xiluodu Zhejiang 800 kv, 7200 MW, Sichuan Hunan 660 kv, 4000 MW, Xiluodu Hunan 660 kv, 4000 MW, Humeng Shandong 800 kv, 7200 MW, Hami Henan 800 kv, 7200 MW, x B2B 3 x 500 kv 7 x 660 kv 19 x 800 kv 5 x 1000 kv Xinjiang Inrfar Mongolia Beijing iaoning Gansu Tianjin Hebei Shanxi Ningxia Shandong Qinghai Henan Shaanxi Anhuj Jiangsu Sichuan & 2 7 Shanghai Xizang hongqing Hubai 26 3 Zheijang Jiangxi Guizhou Fujian Yunnan Guangdong Taiwan 6 24 Hainan Bangkok Heilongjiang Jilin Hunan 21. Baoqing iaoning 660 kv, 4000 MW, Hami Shandong 800 kv, 7200 MW, Tibet hongqing 800 kv, 7200 MW, Jinghong Thailand 500 kv, 3000 MW, Ximeng Wuxi 800 kv, 7200 MW, Baihetan Hubei 800 kv, 7200 MW, Wudongde Fujian 1000 kv, 9000 MW, Northwest North B2B, 1500 MW, Mongolia Jing-Jin-Tang 800 kv, 7200 MW, Russia iaoning 800 kv, 7200 MW, Zhundong Jiangxi 1000 kv, 9000 MW, Tibet Zhejiang 1000 kv, 9000 MW, Baihetan Hunan 800 kv, 7200 MW, Yili Sichuan 1000 kv, 9000 MW, Kazakhstan hengdu 1000 kv, 9000 MW, 2020 Fig. 21 a) World s biggest and longest 800 kv D Transmission Project: Xiangjiaba-Shanghai b) Over 217 GW of additional HVD Transmission apacity are expected in hina between 2010 and 2020 opyright Siemens AG All rights reserved. 18

19 5.3 Super Grid Solutions with GI Gas Insulated ines GI initially was developed in 1974 and At that time, the cost level compared to an overhead line was in the range of 30 times more expensive. ater, in 1998 and 1999, a second generation of GI was developed where the power transmission capability was increased from 2,500 A to 4,000 A and at the same time the cost factor went significantly down in comparison with overhead lines and cables. Fig. 22 gives examples of a new directly buried Bulk Power GI installation in Germany, near the International Airport of the ity of Frankfurt. Site View: Status June 2009 Site View: Status October 2009 aying Process: Pushing the GI Element by Element and Phase by Phase 2010 GI vs. able 2 Systems 4 Systems Same osts ustomer: Amprion ocation: Airport Frankfurt Award of ontract: July 2008 Installation: first directly buried GI Transmission apacity: 2 x 1,800 MVA ength of GI: appr. 1 km Gas for Insulation: 80% N2, 20% SF6 Fig. 22 Bulk Power orridor with GI: 400 kv Installation at Kelsterbach, Germany 6. ONUSIONS AND OUTOOK The security of power supply in terms of reliability and blackout prevention has the utmost priority when planning and extending power grids. The availability of electric power is the crucial prerequisite for the survivability of a modern society and power grids are virtually its lifelines. The aspect of sustainability is gradually gaining in importance in view of such challenges as the global climate protection and economical use of power resources running short. It is, however, not a means to an end to do without electric power in order to reduce O 2 emissions. A more appropriate way is to integrate renewable energy resources to a greater extent in the future (energy mix) and, in addition to this, to increase the efficiency of conventional power generation as well as power transmission and distribution without loss of system security. The future power grids will have to withstand increasingly more stresses caused by large-scale energy trading and a growing share of fluctuating regenerative energy sources, such as wind and solar power. In order to keep generation, transmission and consumption in balance, the grids must become more flexible, i.e. they must be controlled in a better way. State-of-the-art power electronics with HVD and FATS technologies provides a wide range of applications with different solutions, which can be adapted to the respective grid in the best possible manner. D current transmission constitutes the best solution when it comes to loss reduction when transmitting power over long distances. The HVD technology also helps control the load flow in an optimal way. This is the reason why, along with system interconnections, the HVD systems become part of synchronous grids increasingly more often either in form of a B2B for load-flow control and grid support, or as a D energy highway to relieve heavily-loaded grids. FATS technology was originally developed to support systems with long A transmission lines. FATS installations are increasingly more often used in meshed grids to eliminate congestion and opyright Siemens AG All rights reserved. 19

20 bottlenecks. FATS will play its role for strengthening long distance A transmission and meshed grids as well. In conclusion of the previous sections and based on studies and practical experience, the features of the different solutions can be summarized as follows (Fig. 23): Solutions with Overhead ines Note: Power A 1 System 3, D Bipole +/- High-Voltage D Transmission: HVD lassic with 500 / 660 kv (EHV) up to 4 GW HVD Bulk with 800 kv (UHV) 5 GW to 7.2 GW A Transmission: 800 kv A (EHV) 3GVA 1,000 kv A (UHV) 6 to 8 GVA Option UHV D 1,000 kv: 9 GW The Winner is HVD! Solutions with D ables * * Distances over 80 km: A ables too complex 500 / 600 kv D 1 GW to 2GW(with Mass Impregnated ables; actual - prospective) Solutions with GI Gas Insulated ines 400 kv A (HV) 1.8 GVA / 2.3 GVA (directly buried / Tunnel or Outdoor) 500 kv A (EHV) 2.3 GVA / 2.9 GVA (directly buried / Tunnel or Outdoor) 550 kv A (EHV) Substation: Standard 3.8 GVA / Special 7.6 GVA ** 800 kv A (EHV) Tunnel: 5.6 GVA *** Fig. 23 omparison of A and D Bulk Power Transmission Solutions Fig. 23 includes an option for a 1,000 kv UHV D application, which is currently under discussion in hina. This option offers the lowest losses and highest transmission capacity, however, it is obvious that the extended insulation requirements for 1,000 kv will lead to an increase of the already huge mechanical dimensions of all equipment, including PTs, Ts, breakers, disconnectors, busbars, transformers and reactive power equipment. HVD High-Voltage D Transmission: It makes P flow Three HVD Options available: PUS (VS), lassic and Bulk With D, Overhead ine osses are typically % less than with A For able Transmission (over 80 km), HVD is the only Solution HVD can be integrated into the A Systems HVD supports A in Terms of Stability System Interconnection with HVD: D is a Firewall against ascading Disturbances Bidirectional ontrol of Power Flow quite easy Frequency, Voltage and POD ontrol available Staging of the inks with D quite easy No Increase in Short-ircuit Power D is a Stability Booster Fig. 24 Summary: Features and Benefits of HVD ** Reference: Bowmanville, anada, Siemens *** Reference: Huanghe axiwa Hydropower Station, hina, GIT (USA) opyright Siemens AG All rights reserved. 20

21 Regarding long distance Bulk Power transmission, HVD is the best solution, offering minimal losses. The features and benefits of HVD are summarized in Fig. 24. It goes without saying that a combination of FATS and classic line-commutated HVD technology is feasible as well. In the case of state-of-the-art VS-based HVD technologies, the FATS function of reactive power control is already integrated that is, additional FATS controllers are superfluous. However, Bulk Power transmission up to the GW range remains reserved to classic, line-commutated thyristor-based HVD systems. For Bulk Power Transmission over short distances, GI is a very attractive solution due to its high transmission capacity and small right-of-way requirements, in comparison with cables and overhead lines. This includes Bulk Power solutions for supply of both megacities and load centers. GI can also be used in long tunnels and on bridges there are no security and no EMI issues with this technology. The vision of a European Super Grid is gaining impetus since the foundation of the DESERTE Industrial Initiative in The basic idea is the combination of different kinds of renewable energies across Europe a very promising scenario, which has to be developed step-by-step, ref. to Fig. 25. Source: DESERTE Foundation An Initiative of the lub of Rome Siemens has a commitment in the Desertec Industrial Initiative (DII). The objective of this initiative is to develop over the mid-term a technical and economic concept for solar power from Africa. Work will also focus on the clarification of legal and political issues. Fig. 25 Super Grid in Europe: The DESERTE oncept 7. REFERENES [1] European Technology Platform SmartGrids Vision and Strategy for Europe s Electricity Networks of the Future; 2006, uxembourg, Belgium [2] D. Retzmann, Modular Multilevel onverter Technology & Principles and HVD / FATS using VS Applications & Prospects, igré-brazil B4 Tutorial on VS in Transmission Systems HVD & FATS, October 6-7, 2009, Rio de Janeiro, Brazil [3] W. Breuer, D. Povh, D. Retzmann,. Urbanke, M. Weinhold, Prospects of Smart Grid Technologies for a Sustainable and Secure Power Supply ; The 20TH World Energy ongress, November 11-15, 2007, Rome, Italy [4] M. laus; D. Retzmann, D. Sörangr, K. Uecker, Solutions for Smart and Super Grids with HVD and FATS, 17th onference on Electric Power Supply Industry EPSI 2008, October 27-31, Macau, SAR of hina opyright Siemens AG All rights reserved. 21

22 Permission for use The content of this paper is copyrighted by Siemens and is licensed to WE for publication and distribution only. Any inquiries regarding permission to use the content of this paper, in whole or in part, for any purpose must be addressed to Siemens directly. Disclaimer These documents contain forward-looking statements and information that is, statements related to future, not past, events. These statements may be identified either orally or in writing by words as expects, anticipates, intends, plans, believes, seeks, estimates, will or words of similar meaning. Such statements are based on our current expectations and certain assumptions, and are, therefore, subject to certain risks and uncertainties. A variety of factors, many of which are beyond Siemens control, affect its operations, performance, business strategy and results and could cause the actual results, performance or achievements of Siemens worldwide to be materially different from any future results, performance or achievements that may be expressed or implied by such forward-looking statements. For us, particular uncertainties arise, among others, from changes in general economic and business conditions, changes in currency exchange rates and interest rates, introduction of competing products or technologies by other companies, lack of acceptance of new products or services by customers targeted by Siemens worldwide, changes in business strategy and various other factors. More detailed information about certain of these factors is contained in Siemens filings with the SE, which are available on the Siemens website, and on the SE s website, Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in the relevant forwardlooking statement as anticipated, believed, estimated, expected, intended, planned or projected. Siemens does not intend or assume any obligation to update or revise these forward-looking statements in light of developments which differ from those anticipated. Trademarks mentioned in these documents are the property of Siemens AG, its affiliates or their respective owners. opyright Siemens AG All rights reserved. 22