Power Flow Control Solutions for a Modern Grid Using SMART Power Flow Controllers. Kalyan K. Sen

to 1BPSBulk Power SystemBTB‐SSSCBack‐To‐Back SSSCBTB‐STATCOMBack‐To‐Back STATCOMBYPBRKBypass breakerCCapacitancecos(φ)Power factorcpCompensating points of the Sen TransformerCSCConvertible Static Compensatorcr, cs′, cseInterceptdDuty cycleDCDirect CurrentDCLSDC Link SwitchEShunt‐ or series‐connected voltageEHVExtra High VoltageESElectronic SwitchFFarad (unit of capacitance)FACTSFlexible Alternating Current Transmission SystemsFCFixed CapacitorGaNGallium NitrideGHGGreen‐House GasGPFCGeneralized Power Flow ControllerGSTGeneralized Sen TransformerGTOGate‐Turn OffHHenry (unit of inductance)HVHigh VoltageHzHertz (unit of frequency)iInstantaneous current, such as line current (i), exciting current (iex), sending‐end current (is), source current (isrc), and so onILine current magnitudeILine currentIBRInverter‐Based ResourceIECInternational Electrotechnical CommissionIEEEInstitute of Electrical and Electronics EngineersIexExciter current through the primary winding of the Sen TransformerIPFCInterline Power Flow ControllerInNatural line current magnitudeIRImpedance RegulatorIsCurrent at the sending end of the lineIsrcSource currentITCRCurrent through Thyristor‐Controlled ReactorkNumber of TCSC sectionskHzKilo Hertz (unit of frequency)kRFactor, representing the ratio of line resistance, R, when line current is I and the line resistance, Rn, when line current is In.LInductanceLTCLoad Tap ChangerLVLow VoltageMCMagnetic Circuitmr, ms′, mseSlopemsMillisecondMSTMultiline Sen TransformerMvarMega VAR (unit of reactive power)n(subscript) NaturalNCNormally‐ClosedNERCNorth American Electric Reliability CorporationNONormally‐OpenpThree‐phase instantaneous active powerPActive powerPARPhase Angle RegulatorPlinenPower loss in the natural or uncompensated linePlinkActive power on the common linkPrActive power at the receiving end of the linePrhHighest active power at the receiving end of the linePrlLowest active power at the receiving end of the linePrnNatural active power at the receiving end of the linePsActive power at the sending end of the linePseExchanged active power by a Series UnitPshExchanged active power by a Shunt UnitPsnNatural active power at the sending end of the linePsrcActive power at the sourcePs′Active power at the modified sending end of the linePFCPower Flow ControllerPOCPoint of Connection to the utilityPSTPhase‐Shifting TransformerpuPer unitqThree‐phase instantaneous quadrature powerQQuality factorQReactive powerQBQuadrature BoosterQlinenReactive power absorbed by the natural or uncompensated lineQlinkReactive power on the common linkQrReactive power at the receiving end of the lineQrhHighest reactive power at the receiving end of the lineQrlLowest reactive power at the receiving end of the lineQrnNatural reactive power at the receiving end of the lineQsReactive power at the sending end of the lineQseExchanged reactive power by a Series UnitQshExchanged reactive power by a Shunt UnitQsnNatural reactive power at the sending end of the lineQsrcReactive power at the sourceQs′Reactive power at the modified sending end of the linerkVoltage error at a possible kth operating point in the Sen TransformerRLine resistanceR′Resistance of a section of a lineReffEffective line resistanceROMRough‐Order MagnitudeRMSRoot Mean SquareRRReactance RegulatorRseSeries‐compensating resistanceRshShunt‐compensating resistancesSecondSApparent powerSiCSilicon CarbideSMARTSpecific, Measurable, Attainable, Relevant, and Time‐boundSPFCSMART Power Flow ControllerSrApparent power at the receiving end of the lineSsApparent power at the sending end of the line se(subscript) Series‐exchanged, i.e. cse, mse, Pse, Rse, Xse , Qse, ZseSseExchanged apparent power by a Series Unit sh(subscript) Shunt‐exchanged, i.e. Psh, Rsh, Xsh , Qsh, ZshSshExchanged apparent power by a Shunt UnitSSSCStatic Synchronous Series CompensatorSs′Apparent power at the modified sending end of the lineSTSen TransformerSTATCOMSTATic synchronous COMpensatorSVCStatic Var CompensatorSynConSynchronous CondensertTimeTCRThyristor‐Controlled ReactorTHDTotal Harmonic DistortionTNATransients Network AnalyzerTSCThyristor‐Switched CapacitorTSRThyristor‐Switched ReactorTTCTransmission Transfer CapabilityUHVUltra High VoltageUPFCUnified Power Flow ControllerUPSUninterruptible Power SupplyvInstantaneous voltageVPhase voltage magnitudeVPhasor voltageVVolt (unit of voltage)vavolt‐ampere (unit of instantaneous apparent power)VAVolt‐Ampere (unit of apparent power)VARVolt‐Ampere Reactive (unit of reactive power)VRVoltage RegulatorVRTVoltage‐Regulating TransformerVSCVoltage‐Sourced ConverterVdVoltage across the compensating resistanceVdqVoltage across the compensating impedanceVqVoltage across the compensating reactanceVrVoltage at the receiving end of the lineVsVoltage at the sending end of the lineVs′Voltage at the modified sending end of the lineVs′hHighest voltage at the modified sending end of the lineVs′lLowest voltage at the modified sending end of the lineVs′sSeries‐compensating voltageVRVoltage across the line resistanceVRnNatural voltage across the line resistanceVR,XVoltage across the line impedance

VRn,XnNatural voltage across the line impedance

VXVoltage across the line reactanceVXnNatural voltage across the line reactanceWWatt (unit of active power)WECCWestern Electricity Coordinating CouncilXLine reactance (total)X′CCapacitive reactance of a section of a lineXeffEffective line reactanceX′LInductive reactance of a section of a lineXseSeries‐compensating reactanceXshShunt‐compensating reactanceZseSeries‐compensating impedanceZshShunt‐compensating impedance

      Preface

      Both authors have been involved in exploring various power flow controllers since the early 1990s. Kalyan Sen developed power electronics inverter‐based Flexible Alternating Current Transmission Systems (FACTS) models while working at Westinghouse where pioneering development of FACTS products took place. Note that a forced‐commutated inverter with a DC link capacitor is also referred to as a Voltage‐Sourced Converter (VSC). Being an active contributor through patents, publications, design, and commissioning of much‐advertised FACTS controllers since its inception in the 1990s, Kalyan has a first‐hand knowledge of specific applications where the inverter‐based controllers are the desirable solutions and where these solutions are not suitable at all. He has written an award‐winning technical committee paper on the modeling of Unified Power Flow Controller (UPFC) in the IEEE Transactions on Power Delivery. Mey Ling Sen explored an alternate approach to the VSC‐based FACTS Controllers that is cost effective while meeting functional requirements for most utility applications. This effort led to the concept of the Sen Transformer (ST). The ST is fundamentally different from the conventional transformer, in a sense that it uses three primary windings and nine secondary windings to create a compensating voltage that modifies the line voltage to be a specific magnitude and phase angle, whereas the conventional transformer only modifies the magnitude of the line voltage. As a result, by using an ST, the active and reactive power flows in the line can be regulated independently to maximize the revenue‐generating active power flow and minimize the reactive power flow while maintaining the stability of the line voltage.

      Since 2002, Kalyan has traveled around the world as an IEEE Distinguished Lecturer and lectured in more than 150 places in 15 countries. When he gives a presentation on power flow controllers, his approach is to start from the basics and lead up to the advanced concept of VSC‐based FACTS Controllers and ST. His emphasis is based on real‐world experience in modeling, simulation, design, and commissioning. He was requested in many places to compile his lecture material in the form of a book, which resulted in the publication of Introduction to FACTS Controllers: Theory, Modeling, and Applications in 2009. At the inception of the FACTS development in the 1990s, the main concerns were the high installation and operating costs of the FACTS Controllers. Over the decades, the list of drawbacks has expanded to include component obsolescence, costly maintenance, lack of trained‐labor, impracticability of relocation and lack of interoperability. A desired feature of a Power Flow Controller (PFC) is that it is easily relocatable to wherever it is needed the most, since the need for power flow control may change with time due to new generation, load, and so on. Interoperability