A Distributed Static Series Compensator System 2007 (2)

642 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 22, NO. 1, JANUARY 2007

A Distributed Static Series Compensator Systemfor Realizing Active Power Flow Control on

Existing Power LinesDeepak M. Divan, Fellow, IEEE, William E. Brumsickle, Senior Member, IEEE, Robert S. Schneider, Member, IEEE,

Bill Kranz, Randal W. Gascoigne, Dale T. Bradshaw, Member, IEEE, Michael R. Ingram, Senior Member, IEEE,and Ian S. Grant, Fellow, IEEE

Abstract—Flexible AC transmission systems (FACTS) devicescan control power flow in the transmission system to improve assetutilization, relieve congestion, and limit loop flows. High costs andreliability concerns have restricted their use in these applications.The concept of distributed FACTS (D-FACTS) is introduced as away to remove these barriers. A new device, the distributed staticseries compensator (DSSC), attaches directly to existing HV orEHV conductors and so does not require HV insulation. It can bemanufactured at low cost from conventional industrial-grade com-ponents. The DSSC modules are distributed, a few per conductormile, to achieve the desired power flow control functionality byeffectively changing the line reactance. Experimental results froma prototype module are presented, along with examples of thebenefits deriving from a system of DSSC devices.

Index Terms—Distributed FACTS, flexible AC transmission sys-tems (FACTS), interconnected power systems, power system eco-nomics, power system planning, power transmission congestion,power transmission control, power transmission lines.

I. INTRODUCTION

THE U.S. transmission system was developed to serve avertically integrated regulated utility structure. Substan-

tial changes and capital investment are required to modify it forderegulated market needs. Thus it presents a major infrastruc-tural obstacle for the continuing growth of the U.S.$ 224 billionU.S. electricity market [1]. Electricity demand has increased25% over the last decade and continues to increase. Overall, ad-equate generation capacity now exists, or is planned, to meetprojected needs in the U.S. At the same time, annual investmentin transmission facilities has declined over the last decade [1].

Manuscript received December 3, 2004. This work was supported in part bythe Tennessee Valley Authority and in part by Soft Switching Technologies Cor-poration. Paper no. TPWRD-00573-2004.

D. M. Divan was with Soft Switching Technologies, Middleton, WI 53562USA. He is now with the Georgia Institute of Technology, Atlanta, GA 30332USA (e-mail: [email protected]).

W. E. Brumsickle, R. S. Schneider, and B. Kranz are with Soft SwitchingTechnologies, Middleton, WI 56562 USA (e-mail: [email protected]).

R. Gascoigne was with Soft Switching Technologies, Middleton, WI 53562,USA. He is now a Consultant in Madison, WI 53711 USA.

D. T. Bradshaw was with the Tennessee Valley Authority, Chattanooga,TN 37402, USA. He is now with Electrivation, Chattanooga, TN 37416 USA(e-mail: [email protected]).

M. R. Ingram and I. S. Grant are with the Tennessee Valley Authority, Chat-tanooga, TN 37402 USA (e-mail: [email protected]; [email protected]).

Color versions of Figs. 2–11 are available online at http://ieeexplore.ieee.org.Digital Object Identifier 10.1109/TPWRD.2006.887103

As a result of load growth, deregulation, and limited investmentin new facilities, transmission congestion has rapidly increased.Over 50 transmission corridors in the U.S. are routinely con-gested, causing high economic impact. According to the NewYork Independent System Operator (NYISO), T&D system con-gestion costs over U.S.$ 1 billion per year [2].

Unfortunately, ac power flow follows Ohm’s Law, not con-tract law. Uncontrolled ‘loop flow’ causes congestion and reli-ability problems, and reduces the ability to fulfill energy con-tracts. Loop flows also impact the ability to fully utilize certaintransmission lines, even as other lines suffer congestion, furtherlimiting available transfer capacity under normal and contin-gency conditions.

New transmission lines could relieve congestion, but areexpensive to build (U.S.$ 0.5–2 million/mile typically, but costscan exceed U.S.$ 10 M/mile) and require several years forapproval and construction. One solution to the problem of man-aging power flow on transmission lines has been through theuse of Flexible AC Transmission Systems (FACTS). FACTSdevices allow control of power flows on ac power systemsthrough the use of large power converters (10–300 MW) [3].While several FACTS installations are operating worldwide,wide scale deployment has not occurred. FACTS typically costsU.S.$ 120–U.S.$ 150 per kVAr, compared to U.S.$ 15–U.S.$20/kVAr for static capacitors.

This paper introduces the concept of a distributed static seriescompensator (DSSC) that uses multiple low-power single-phaseinverters that attach to the transmission conductor and dynam-ically control the impedance of the transmission line, allowingcontrol of active power flow on the line [4]. The DSSC invertersare self-powered by induction from the line itself, float electri-cally on the transmission conductors, and are controlled usingwireless or power line communication techniques. Implementa-tion of system level control uses a large number of DSSC mod-ules controlled as a group to realize active control of power flow.The DSSC can be used to either increase or decrease the ef-fective line impedance, allowing current to be “pushed” awayfrom or “pulled” into a transmission line. The DSSC conceptovercomes some of the most serious limitations of FACTS de-vices, and points the way to a new approach for achieving powerflow control–the use of Distributed FACTS or D-FACTS de-vices. This paper details the principles of operation of the DSSC,shows operating results from a prototype device, and presents ananalysis of its possible impact on typical power systems.

0885-8977/$20.00 © 2007 IEEE

DIVAN et al.: DSSC SYSTEM FOR REALIZING ACTIVE POWER FLOW CONTROL 643

TABLE ITYPES OF FACTS DEVICE

II. FEATURES AND LIMITATIONS OF FACTS DEVICES

FACTS devices are typically high-power high-voltage powerconverters, operating at 138–500 kV and 10–300 MVA, that areused to control power flow in the transmission and distributionnetwork. Three basic types of FACTS devices can be identifiedas shown in Table I [5].

Shunt devices such as the static VAR compensator (SVC)and static synchronous compensator (STATCOM), have beenmost widely applied, and are typically used for reactive VARcompensation and voltage support. Series devices such as thethyristor controlled series capacitor (TCSC) and the static syn-chronous series compensator (SSSC) can be used for controllingactive power flow on transmission lines. Series-shunt devicessuch as the universal power flow controller (UPFC) can be usedfor accomplishing both functions with maximum flexibility, andhigher cost.

For controlling power flow on transmission lines, the serieselements clearly have the highest potential and impact. The realand reactive power flow, and , along a transmission lineconnecting two voltage buses is governed by the two voltagemagnitudes and and the voltage phase angle difference,

, as

and

(1)

where is the impedance of the line, assumed to be purelyinductive. A series compensator is typically used to increaseor decrease the effective reactive impedance of the line,thus allowing control of real power flow between the two buses.The impedance change can be effected by series injection ofa passive capacitive or inductive element in the line. Alterna-tively, a static inverter can be used to realize a controllable ac-tive loss-less element such as a negative or positive inductor or asynchronous fundamental voltage that is orthogonal to the linecurrent [6], [7]. In the latter case, the power flow depends on theinjected quadrature voltage as

(2)

Fig. 1. Variation of transmission line power flow by impedance injection. (a)Passive impedance injection, as p.u. ofX (TCSC). (b) Quadrature voltage in-jection to achieve active impedance injection (SSSC, DSSC).

and the bracketed term is unity if . Fig. 1 shows,for equal bus voltage magnitudes, the variation of power flowalong a transmission line that can be achieved by injecting apassive impedance or an active impedance [7].

Significant barriers remain to the widespread commercial de-ployment of FACTS. Ratings of FACTS devices are often in the100 MW range, with system voltages of 138 to 500 kV. Further,series injection devices such as TCSC and SSSC, require plat-forms or custom transformers for isolation, and need to handlefault voltages and currents. This approach to system implemen-tation has resulted in large and complex converter installationsand barriers that have, so far, limited the commercial success ofFACTS technology. These include:

• high-cost resulting from device complexity and componentrequirements;

• single point of failure can cause the entire system to shutdown;

• maintenance and on-site repair requirements for a complexcustom-engineered system adds significantly to system op-erating cost and increases mean time to repair (MTTR);

• lumped nature of system and initial over-rating of devicesto accommodate future growth provides poor return on in-vestment (ROI);

• custom engineered nature of system results in long designand build cycles, resulting in high system cost that will noteasily scale down with volume.


Fig. 2. DSSC concept showing clamp-on capability.

III. DISTRIBUTED STATIC SERIES COMPENSATOR (DSSC)

A controlled transmission system can be made up of alarge number, e.g., hundreds or thousands of DSSC modules,each module containing a small rated (1–20 kW) single phaseinverter, a communications link and a single turn transformer(STT) that is mechanically clamped on to—and suspendedfrom—the transmission line conductor (or insulator). TheSTT uses the transmission conductor as a secondary winding,directly injecting the desired voltage into the cable itself. Theinverter is self-powered by induction from the line, and canbe controlled to inject a voltage that is orthogonal to the linecurrent directly into the conductor. The module can either besuspended from the conductor or configured as a replacementfor the conductor support clamp on an insulator. Further,since it does not require supporting phase-ground insulation,the module can easily be applied at any transmission voltagelevel. Fig. 2 shows an electro-mechanical concept diagramfor a typical DSSC module, while Fig. 3 shows the powercircuit schematic. The mechanical form of the module mayeither clip-on to the conductor, as shown in Fig. 2, or may beincorporated into the insulator suspension clamp, avoiding anyconcern about weight and conductor vibration damage.

When the transmission line is not powered up, the STT is by-passed by a normally closed relay contact (R1) that opens oncecontrol power is available. A current transformer is used to gen-erate control power, allowing the DSSC module to operate aslong as the line current is greater than a minimum level, say 150A. The line appears to the inverter as an inductive current source.The single phase inverter uses four IGBT devices along with anoutput LC filter and a dc bus capacitance. The inverter outputvoltage is controlled using pulse width modulation techniques,and has two components. The first is in quadrature with the linecurrent, and represents the desired impedance to be injected.The second is in phase with the line current, and allows compen-sation of power losses in the inverter, and regulation of the dc

Fig. 3. DSSC circuit schematic.

bus of the inverter. System commands for gradual changes arereceived from a central control center using a wireless or powerline communication (PLC) technique [8]. In the event of rapidtransients or faults the DSSC modules can be programmed tooperate autonomously. With the DSSC attached and operatingat the conductor potential, conductor temperature measurementcapability is easily added and actual temperature readings canbe communicated to the central system controller.

The STT is a key component of the DSSC module. It is de-signed such that the module can be clamped onto an existingtransmission line. The STT is designed with a high turns ratio,say . This implies that under a normal line current of say1500 A, the inverter would only handle 20 amperes. Designingthe inverter for 500 volts rms output would then allow the DSSCmodule to inject 7 V rms leading or lagging, corresponding to

kVAr in series with the line under normal operating condi-tions. It is anticipated that such a module could be designed toweigh less than 45 kg (100 lb), making the module suitable fordirect clamp-on mounting on the transmission conductor.

The STT also allows the inverter to possibly continue oper-ating under fault conditions. For instance, at a fault current of50 000 A, the inverter current is still only 667 A, well within thecapability of commercially used IGBT devices. This raises theinteresting possibility that unlike TCSCs, the DSSC could reg-ulate line impedance under normal conditions, switching intoa maximum inductance injection mode within microseconds toprevent an increase in the fault current levels.

The inverter ratings clearly demonstrate that the semiconduc-tors and components used are commercially available in veryhigh volumes for the motor drives, UPS, and automotive indus-tries, thus validating the potential for realizing low cost.

IV. OPERATION OF DSSC IN POWER SYSTEMS

A controlled transmission line implemented with multipleDSSC modules can realize significant benefits at a system level.At the highest level, it can:

• enhance asset utilization;• reduce system congestion;• increase available transfer capacity (ATC) of the system;


Fig. 4. Meshed network system DSSC implementation.

• enhance system reliability and capacity under contingen-cies;

• enhance system stability.and can do so with lower capital and operating cost than mostconventional single-point “lumped” solutions, such as FACTSdevices.

An overall meshed network system implementation is shownschematically in Fig. 4. DSSC modules can be deployed on se-lect lines, or on all lines. Overall operation of the modules is co-ordinated using a single (or redundant) communication channel(RF or PLC), with a built-in fail-safe operating mode in caseof fast transients (such as system faults) or communication linkfailure. A typical system level command could be for the DSSCmodules to emulate a desired impedance or voltage as a functionof line current. For instance, the line impedance could automat-ically increase above a current set point, causing current to bepreferentially steered to other lines that are lightly loaded.

Operation of the DSSC modules can be coordinated from thesystem control center to realize a variety of optimization func-tions or operating conditions including:

• system optimization, e.g., loss or VAr minimization;• maintaining lines out of congestion or below thermal limit;• reconfiguring current flows to compensate for tripped lines;• operating lines above steady-state thermal limit under con-

tingency conditions;• forcing power to flow along contract paths;• controlling power flow through flow-gates;• decreasing susceptibility to sub-synchronous resonance;• marginal reduction of fault currents;• providing damping of system oscillations.The DSSC modules are insensitive to the cable voltage rating,

and are targeted for 138 kV to 500 kV systems. The maximumlevel of impedance control for specific lines is projected at upto – % of the actual line impedance under rated currentconditions. At lower current levels, the range of impedance con-trol can be correspondingly increased. For instance, at half thenominal current, the impedance control range can be doubled.The distributed nature of the proposed system also provides finegranularity in the system rating, along with the ability to expandthe system with demand. System planners can thus plan on in-creasing the ATC of a line by 2% every year for 10 years to meet

TABLE IICALCULATION OF NUMBER OF DSSC MODULES TO CHANGE

LINE IMPEDANCE BY 1%

Fig. 5. DSSC control of power flow over parallel lines connecting voltagebuses: uncompensated (top) and with DSSC compensation (bottom).

projected growth needs, without having to invest all the capitalat project start.

Table II shows the characteristics of typical lines at 138 to765 kV, and examines the applicability of DSSC technology torealistic applications. Transmission lines are considered to betypical and representative.

Taking the 138 kV line as an example, it is seen that the reac-tive voltage drop is 608 V/mile at rated current (correspondingto 0.79 ohms/mile). A 1% change in the impedance thus requiresan injection of 6.08 V/mile, corresponding to a combined DSSCrating of 14 kVA/mile based on three phase injection. A varia-tion of % in line impedance would thus need 280 kVA or 28of the 10 kVA DSSC modules/mile or approximately 9 modulesper conductor per mile.

A. Examples

Fig. 5 shows a simple example of how the DSSC can be con-trolled so as to relieve transmission congestion. Two lines ofunequal lengths are used to transfer power from bus 1 to bus2. The assumed line parameters are listed in Table III. Setting

yields line currents of A, andA, and power transferred along the lines is MW and

MW, for a total power transfer of 268 MW betweenthe buses.

Assuming a DSSC in each line, increasing by 20% anddecreasing by 20% allows use of a larger phase angle

, which results in A giving MW, andA and MW, for a total power transfer of

319 MW between the buses. These results are summarized inTable IV. The power transferred through line 2 has increasedby almost 50%, while line 1 has been controlled to well withinits thermal limit. Approximately 10.9 MVA of control action,


TABLE IIILINE PARAMETERS FOR EXAMPLE OF FIG. 5

TABLE IVPOWER TRANSFER BETWEEN TWO BUSES

achieved with 1092 DSSC modules spread over 50 miles oftransmission lines—7.3 modules per mile per conductor, re-sulted in 51 MW of additional power flow between buses. Thisnumber would be even more advantageous at higher systemvoltages. This simple example confirms the ability of the DSSCto control loop flows, to manage congestion, and to increase thepower handling capacity of transmission lines.

V. LUMPED VERSUS DISTRIBUTED SOLUTIONS

The distributed nature of the DSSC system provides severalbenefits. A significant benefit accrues from the ability to stagecapital investments over a longer time, and being able to matchthe investment with the actual need or demand. For instance,system planners exploring the addition of a FACTS system suchas an SSSC or a phase shifting transformer to increase line ATCwould typically plan on a 30 year system operating life, and haveto design the system to handle the growth in demand expectedover that period. Since only a portion of the system capacitywould be usefully deployed in the first year, this suggests thatthe return on capital employed (ROCE), a key financial metricfor most organizations, would be low. By way of contrast, asystem implemented with DSSC could be expanded every yearin tandem with actual load growth, and would maximize the uti-lization of capital. A simple example is used to show the differ-ence.

The 30 mile transmission line shown in Fig. 5 is assumed tooperate with an average line current of 340 A (45% of thermallimit), growing at 2.5% per year to 713 A (95% of thermal limit)in 30 years. Lumped and distributed series compensators (orphase shifting transformer) are to be compared as solutions tocontrol power flow on the line. Ratings for the two solutionsare: 1) Lumped: a 19.13 MVA SSSC installed beginning of year1; 2) Distributed: 0.64 MVA of DSSCs installed annually for30 years. Deployment of either solution allows power flow toincrease from 81.2 MW in year one to 170.3 MW by year 30.

TABLE VCOST COMPARISON FOR LUMPED VERSUS DISTRIBUTED SOLUTIONS

IN A 138 KV/750 A LINE (U.S. DOLLARS)

Significant differences are seen to occur in capital cost and op-erating cost (energy losses) for the two solutions. Table V sum-marizes the overall impact on cost of ownership.

Assumptions—for the purposes of the example summarizedin Table V—include U.S.$ 100/kVA first cost for either solution,a 6% annual cost of capital over 30 years, 2.5% per annum loadgrowth, nominal energy losses of 2.5% (under full voltage andcurrent conditions) and an energy cost of U.S.$ 25/MWh. Withtoday’s FACTS capital costs at U.S.$ 120–U.S.$ 150/kVA, andDSSC costs expected to be well below U.S.$ 100/kVA, the ad-vantages of the distributed system appear even more compelling.

Another important issue relates to the inaccuracy of the esti-mated growth rates that are the basis of the economic decision. Ifthe achieved rate of demand growth is lower than the projected2.5%, the distributed solution can be deployed only as required,with minimal impact on the overall cost recovery and return oninvestment. On the other hand, for lumped solutions, a slower rateof growth would dramatically reduce the return on investment.

VI. OPERATIONAL AND ECONOMIC BENEFITS

From an operational perspective, the following characteristicsmay be realized for DSSC systems:

• ability to increase or decrease steady state line currentunder system controller command, or autonomously;

• ability to monitor actual conductor temperature and man-ually or automatically limit currents as a function of con-ductor temperature;

• high system reliability due to massive redundancy, singleunit failure has negligible impact on system performance;

• zero footprint solution;• robust and rugged under typical fault conditions;• can be used with conventional or advanced conductors;• mass produced modules can be stocked on the shelf, and

repaired in the factory—does not require skilled staff onsite;

• easy and rapid installation (may be possible on live line).These operational benefits, in turn, lead to significant economicbenefits. These include:

• simple scalable tool for congestion management—increaseATC and revenues;

• improves contingency management capability—reduceTLR calls and meet contingency operating requirementswithout building new lines;

• minimize loop flows and wheeling losses—improved assetutilization and lower operating cost;

• reduce trapped capital in assets sized for future projectedgrowth—improves return on capital employed (ROCE);


Fig. 6. DSSC prototype with suspension clamps.

TABLE VIPROTOTYPE DSSC MODULE SPECIFICATIONS

• improves flexibility of locating new generation and allowspower flow along the contract path—enables bulk energytrading and reduces overall energy costs;

• incrementally increase line capacity and defer new lineconstruction—minimize environmental impact, right ofway, and NIMBY issues

VII. EXPERIMENTAL VERIFICATION

A prototype module was designed, built, and tested to vali-date the DSSC concept. The DSSC module, shown in Fig. 6, iscompletely enclosed and designed for suspension from a trans-mission line. It operates in a self-exciting mode, drawing a smallreal power component from the line for control power and in-ternal losses. This prototype was not designed for extended op-eration suspended on HV transmission systems, nor for mini-mization of corona effects.

Fig. 7. DSSC start-up waveforms at 1500 Arms.

Fig. 8. DSSC steady-state waveforms at 1500 Arms and maximum positiveinjection. Note: voltage amplitude is scaled by a factor of 100.

Key module specifications are summarized in Table VI.The power losses in the DSSC module were measured using aVoltech model PM 3000A power analyzer.

A. Module Testing Results

Laboratory testing was done at 480 Vrms with a 3000 kVAtransformer (5.75% impedance) source and resistive loads.Fig. 7 shows operating waveforms as the module starts upat 1500 Arms. The inverter voltage is in phase with the linecurrent as real power is extracted from the line to charge theinverter DC bus capacitors. Fig. 8 shows steady-state operatingwaveforms; note that the injected voltage is orthogonal to theline current, and represents a positive inductance injection.

In case of overload current levels, e.g., with transmissionfaults, the DSSC protects itself by quickly shorting the trans-former primary winding, first using the inverter IGBTs, thenwith a normally closed mechanical relay. Unlike solutions suchas the TCSC, the DSSC modules do not contribute to the systemfault current, and actually operate to reduce it. The protectionfeatures were demonstrated under simulated 15 000 Armscurrent surge conditions by temporarily switching 1 500 A intoa ten-turn coil that was placed in parallel with the single-turnline conductor carrying 350 Arms initially. Fig. 9 shows theresulting voltage and combined effective current waveforms atfull negative insertion output. The DSSC inverter voltage canbe seen to quickly collapse to zero during the current surge.


Fig. 9. DSSC operation under 7-cycle 15k Arms fault current. Note: voltageamplitude is scaled by a factor of 10.

Fig. 10. Simulated parallel transmission lines lab setup. Values are per unit ona 480 V, 333 kW base. Line 1 is on top, Line 2 on the bottom.

The unit automatically restarted at its previous command pointafter the fault current condition cleared.

B. Current Steering in Parallel Transmission Lines

A laboratory simulation of parallel transmission lines be-tween a voltage bus and a load bus was configured as shown inFig. 10. Identical inductors were placed in series with each oftwo 500 kcmil cables to provide a representative per unit lineimpedance. The DSSC is represented as a variable inductance.

in Fig. 10, injected quadrature voltage to effectivelychange the line currents while keeping the DSSC current abovethe operational minimum of 330 Arms. The resulting rms cur-rent profiles, as the DSSC output is varied, are shown in Fig. 11.The effects of “pushing current away” and “pulling current into”the controlled line are evident. By design, this prototype unitoperates with line currents down to 330 A. DSSC designs oper-ational to 100 A or less are possible.

C. Extension to Transmission System Usage

The module test data allow us to calculate the impact of de-ploying the DSSC modules in a power system, such as that de-picted in Fig. 5. Assuming 10 modules per conductor mile, onesees that the energy losses when the system is in bypass modetotal 800 watts/mile at 1 000 A. The insertion inductance inbypass mode is 8 H/mile or 0.003 ohms, as compared witha typical transmission conductor impedance of approximately0.8 ohms/mile, representing a 0.37% change in line impedance.When the system is operating at full output, the total DSSCsystem losses are estimated at 14.7 kW/mile (for three phases)to achieve a 5.1% increase in current and MVA, compared with239 MVA of power flowing through the transmission system atthe rated operating point (138 kV/1000 A). It is anticipated that

Fig. 11. Current steering effect of DSSC quadrature voltage injection as in-jected voltage is varied from maximum negative injection at time zero, to max-imum positive injection at time 10 s, to zero injection at time 25 s.

these losses can be considerably reduced in a final productionversion of the DSSC, through optimization of component mate-rials.

VIII. CONCLUSION

This paper has presented the novel concept of a DSSC thatuses multiple low-power single-phase inverters that clip-onto the transmission conductor to dynamically control theimpedance of the transmission line allowing control of activepower flow on the line. The DSSC inverters are self-poweredby induction from the line itself, float electrically on the trans-mission conductors, and are controlled using wireless or powerline communication techniques. Implementation of systemlevel control uses a large number of DSSC modules that aredeployed and controlled as a group to realize active controlof power flow. The DSSC can be used to either increase ordecrease the line impedance, allowing current to be ‘pushed’away from or “pulled” into a transmission line in a networkedsystem. The DSSC concept overcomes some of the most se-rious limitations of FACTS devices, and points the way to anew approach for achieving power flow control—the use ofDistributed FACTS or D-FACTS devices. This paper details theprinciples of operation of the DSSC, shows operating resultsfrom a prototype device, and presents a preliminary analysis ofits possible impact on typical power systems. Although manyaspects of implementation have yet to be explored, this paperhas demonstrated the fundamental concept is sound and theeconomics are compelling.

ACKNOWLEDGMENT

The authors acknowledge the contributions of Rick Mills inhis work on the DSSC prototype packaging.

REFERENCES

[1] S. Abraham, National Transmission Grid Study U.S. Dept. Energy,May 2002 [Online]. Available: http://www.eh.doe.gov/ntgs/.

[2] W. J. Museler, President and CEO of the New York Indepen-dent System Operator (NYISO) May 22, 2003. New York City[Online]. Available: http://www.nyiso.com/topics/articles/news_ re-leases/2003/pa3_presentation.pdf.


[3] N. Hingorani, “Flexible AC transmission,” IEEE Spectr., vol. 30, no.4, pp. 40–45, Apr. 1993.

[4] D. M. Divan, W. Brumsickle, and R. Schneider, “Distributed floatingseries active impedance for power transmission systems,” U.S. Patent7 105 952, Sep. 2006.

[5] D. J. Gotham and G. T. Heydt, “Power flow control and power flowstudies for systems with FACTS devices,” IEEE Trans. Power Syst.,vol. 13, no. 1, pp. 60–65, Feb. 1998.

[6] D. M. Divan, “Non-dissipative switched networks for high power appli-cations,” Inst. Elect. Eng. Electron. Lett., pp. 277–279, Mar. 20, 1984.

[7] L. Gyugyi, C. D. Schauder, and K. K. Sen, “Static synchronous se-ries compensator: A solid-state approach to the series compensationof transmission lines,” IEEE Trans. Power Del., vol. 12, no. 1, pp.406–417, Jan. 1997.

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Deepak M. Divan (S’78–M’78–SM’91–F’98) is Professor in the School ofElectrical and Computer Engineering and Director of the IPIC Consortium atthe Georgia Institute of Technology (Georgia Tech), Atlanta. He is Chairmanand Chief Technology Officer for Innovolt, Atlanta. From 1995 to 2004, he wasChairman and CEO/CTO of Soft Switching Technologies, a company in the in-dustrial power quality market. His research interests are in the application ofpower electronics for power quality, power reliability, and utility and industrialapplications. He has more than 200 papers and 28 issued and 4 pending patents.

Dr. Divan was the recipient of the 2006 IEEE William E. Newell Award forcontributions in power electronics. He is a Member at Large of the IEEE PowerElectronics Society and is PESC Steering Committee Chair for the society. He isTechnical Chair for the 1991 PESC Conference and Chairman and TransactionsEditor for the IAS-IPCC committee.

William E. Brumsickle (A’89–S’92–M’98–SM’05) received the B.S. degreein physics from the University of Washington, Seattle, in 1982, and the M.S.and Ph.D. degrees in electrical engineering (power and energy systems) fromthe University of Wisconsin-Madison in 1995 and 1998, respectively.

He was an Applications Engineer for static power conversion productsat Enerpro, Inc., Goleta, CA, from 1985 to 1992. From 1992 to 1998, heparticipated in Wisconsin Electric Machines and Power Electronics Consor-tium (WEMPEC) research projects in soft switching converters, active filters,power-electronics building blocks (PEBB), large-scale uninterruptible powersupplies (UPS), and traction drive applications of high-voltage insuated-gatebipolar transistors (IGBTs). In 1998, he joined Soft Switching Technologies,Middleton, WI, where he is Director of Engineering. His research interestsinclude power-electronics conversion for utility and industrial applications,soft switching inverter design and control, and the physics, monitoring, andmitigation of power-quality disturbances.

Robert S. Schneider (M’90) received the B.S. degree in physics from the Uni-versity of Wisconsin–Eau Claire in 1982 and the M.S. degree in electrical en-gineering from the University of Wisconsin–Madison in 1986, where he is cur-rently pursuing a second M.S. degree in controls.

Currently, he is a Lead Engineer, Power Electronics, with Soft SwitchingTechnologies (SST), Middleton, WI. He was the Project Leader and PrincipleHardware Designer for the first generation of the DySC line of products thatspanned a range of 1.5 kVA through 1.33 MVA. He has more than 18 yearsof industrial experience in designing and field testing power-electronic con-verters and systems, including implementation of photovoltaic, battery storage,motor drive, servo motor, mini-hydroelectric, distributed generation, and power-quality systems. He has been involved in automatic voltage regulators, single-to-three-phase motor drives, and the introduction of demand flow manufacturingtechnology for DySC products. He is a Co-inventor of three of SST’s patentedproduct technologies. He is a licensed Professional Engineer in the State of Wis-consin.

Bill Kranz received the B.S. degree in electrical engineering from the Univer-sity of Wisconsin–Madison in 1999.

Currently, he is a Lead Engineer, Embedded Controls, with Soft SwitchingTechnologies Corp., Middleton, WI. His research interests include real-timesoftware and analog controls for industrial and utility power protection systems,power quality, and voltage monitoring equipment, and fue–cell-based inverters.

Randal W. Gascoigne received the B.S.E.E. degree from the University of Wis-consin–Madison in 1982.

He was with the University of Wisconsin–Madison, engineering custom in-strumentation and controls for a wide variety of applications. From 1987 to1995, he was a Lab Manager with the staff of the Wisconsin Electric Machinesand Power Electronics Consortium (WEMPEC). From 1995 to 2004, he was aSenior Engineer for Soft Switching Technologies (SST), Middleton, WI, wherehe continued to apply his expertise in circuit design, component selection/speci-fication, and packaging/system design. He also designs and builds electrical fishbarrier controllers for the Wisconsin Department of Natural Resources, and en-joys applying electronics to provide unique solutions to problems in other fieldsof endeavor.

Dale T. Bradshaw (M’98) is President of Electrivation, Chattanooga, TN. Heis External Program Coordinator for National Rural Electric Cooperative As-sociation’s (NRECA) Cooperative Research Network’s (CRN) TransmissionReliability and Security Advisory Group; Emerging Technology Team Leaderfor the U.S. DOE NETL’s Modern Grid Initiative and University of California,San Diego’s Smart Grid; Consultant to the California Institute for Energy andEnvironment (CIEE) Transmission Research Program; Consultant to Naviganton the assessment of DOE’s High Temperature Superconductivity Program;Project Manager for an NRECA Project to identify options for mitigating trans-mission congestion; Director of Marketing for V&R Energy’s Physical Oper-ating Margin (POM) suite of transmission system analysis software; TechnicalAdvisor to DOE’s Office of Electric Transmission and Distribution (OETD);Business Development Consultant for Intelicis; Consultant for a major U.S. fly-wheel manufacturer; CTO for Advanced Coal Technologies LLC; and a GLGLeader consulting with Gerson Lehrman Groups Council of Advisors. He waswith the Tennessee Valley Authority and was Senior Manager of Power DeliveryTechnology from 1996 until 2004, where he developed projects that improvedtransmission grid operations with operational planning, transmission asset uti-lization with the transmission planning group, and transmission performancewith transmission operations. He and his staff developed, demonstrated, and/orimplemented transmission planning optimization software, improved conductorsplice repair, improved transmission oil analysis, improved transmission oil ad-ditives, dynamic line rating systems, reduced cost capacitor design, and lowercost dynamic reactive compensation systems.

Michael R. Ingram (M’91–SM’96) received the B.E.E. degree (Hons.) fromAuburn University, Auburn University, AL, and the M.S. degree in engineeringmanagement from the University of Tennessee, Chattanooga.

Currently, he is the Senior Manager of Transmission Technologies with theTennessee Valley Authority (TVA), Chattanooga, TN. He is responsible for theresearch, development, and demonstration of new technologies which improveelectrical quality and reliability, increase power flow, and reduce operating ex-pense of the TVA transmission system and interconnected distribution network.He provides advice to TVA executives on new technology solutions affectingthe T&D networks and sets strategy for research and development in areas ofenergy storage, power quality, power/transmission markets, flexible ac trans-mission systems (FACTS), and superconductivity. He has been with TVA for17 years, working in technical project management, protection and control en-gineering, and substation design. He has authored or coauthored more than 30technical papers and articles within his area.

Mr. Ingram was the Chairman or Committee Member of several users andworking groups of IEEE, EPRI, and CIGRE. He was named Outstanding YoungEngineer of the Year (2001) by The IEEE Power Engineering Society. He wasnamed Engineer of the Year in 2001 and 2006 by the TVA. Additionally, he wasa 2001 and 2006 top-ten finalist for Federal Engineer of the Year. Other profes-sional awards include IEEE Millennium Medal; Outstanding Power Engineerof the Year, 1997; and Chattanooga-Area Young Engineer of the Year, 1996.

Ian S. Grant (F’87) received the B.E. degree from the University of NewZealand, Auckland, in 1962 and the M.E. degree from the University of NewSouth Wales, Sydney, Australia, in 1967.

After graduation, he joined the Electricity Commission of NSW, Sydney,Austalia, followed by General Electric Co. High Voltage Laboratory, Pittsfield,MA; Power Technologies, Inc., Schenectady, NY; Evonyx, Inc., Hawthorn, NY;and the Tennessee Valley Authority (TVA), Chattanooga, TN. Currently, he isPlanning Coordinator with TVA’s Transmission Reliability Operation. He is theauthor or coauthor of more than 45 papers and books on transmission design,lightning and transient studies, and insulation coordination.

Documents

A Distributed Static Series Compensator System 2007 (2)