PSERC. HICSS-34 Tutorial 14 January 3, 2001 mgrid Operation and Control. Robert H. Lasseter University of Wisconsin

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1 HICSS-34 Tutorial 14 January 3, 2001 mgrid Operation and Control Robert H. Lasseter University of Wisconsin Giri Venkataramanan University of Wisconsin A. P. Sakis Meliopoulos Georgia Institute of Technology 2001 University of Wisconsin Board of Regents University of Wisconsin and Georgia Institute of Technology 1

2 HICSS-34 Tutorial 14 Micro-Grid Operation and Control Robert H. Lasseter University of Wisconsin A.P.Sakis Meliopoulos Georgia Institute of Technology Giri Venkataramanan University of Wisconsin R.H.Lasseter University-of-Wisconsin

3 Outline 1. Overview of Micro-sources (1/2 hr) 2. Problems and Issues related to Distribution Systems (1 hr) 3. Power Electronics (1hr) 4. Operation and Control of Micro-Grids Needs and Challenges (1/2Hr) R.H.Lasseter University-of-Wisconsin

4 Power Generation Applications 100s MWs Central Plant Power Generation Distributed Generation 1 MW T/D grid On site generation kws Peaking units: Cost deferrals: Voltage support: Back-up power Local power & heat Isolated site Local voltage support Cost reduction Load management Micro Grid R.H.Lasseter University-of-Wisconsin

5 Micro-Turbine Basics Hot Air Recuperator Turbine Generator Air Compressor Power electronics 3 Phase ~ 480V AC R.H.Lasseter University-of-Wisconsin

6 70kW Micro turbine Installed at $1000/kW (target is $350/kW) Efficiency 30% Air foil bearings expect in excess of 40,000 hours of reliable operation. Operation speed 90, ,000 RPMs R.H.Lasseter University-of-Wisconsin

7 Fuel cell System R.H.Lasseter University-of-Wisconsin

8 Automotive Influence on Fuel Cell Development Experimental F.C. car (Toyota) Prototype F.C. cars (G.M., D- C., Toyota) Production of F.C. vehicles Daimler-Chrysler $324 million investment Fuel cell buses commonplace Car Fuel Cells must be under $100/kW R.H.Lasseter University-of-Wisconsin

9 Ballard PEM Fuel Cell R.H.Lasseter University-of-Wisconsin

10 7 kw Plug Power System PEM Fuel Cell/water heater QuickTime and a Photo - JPEG decompressor are needed to see this picture. R.H.Lasseter University-of-Wisconsin

11 Distributed Generation Business Characterization U. S. Electricity Market $250 Billion Per Year Distributed Generation Expected to Capture 10-20% of Market in 10 years Players - Illustrative List Allied-Signal Micro-Turbines Siemens Fuel Cells Solar Turbine/Caterpillar Tractor Engines/turbines Capstone Turbine Micro-Turbines GE Fuel Cells/Turbines Others - Ballard, Allison, Williams, Plug Power, PowerCell R.H.Lasseter University-of-Wisconsin Commercial Units/Packaged Solutions Coming to Market

12 Generation Efficiencies 1 MW 70% 60% With CHP CHP Hybrid Fuel cell CCTG 50% Fuel Cell 40% 30% Micro Turbine 20% 10kW 100kW 1 MW R.H.Lasseter Reciprocating Engines Gas Turbine University-of-Wisconsin Old steam 10MW 100MW 1000MW

13 On Site Generation Microturbine PA Fuel Cells PEM Fuel Cells Hybrid FC/MT Roof top PV Recip Engine kw kw kw kw kw MW Efficiencies 30/80% 40/78% 40/78% <70% 38/80% Power Electronic interface R.H.Lasseter University-of-Wisconsin

14 Factors Impacting Grid Connectivity GENERATOR TYPE INTERCONNECTION VOLTAGE GENERATOR ELECTRIC CHARACTERISTICS Synchronous - hydro, engine-driven Induction - wind turbines, small hydro Power electronic - micro turbines, fuel cells, self-commutated line-commuted Transmission > 66 kv Sub transmission kv Distribution 4-16 kv Customer V Rating Small Fault Current Islanding Voltage Control R.H.Lasseter University-of-Wisconsin

15 Micro-source Issues Low power < 100 kw Low voltage volts Inertia-less Power electronic interface Interconnection cost Control (large numbers) Market interactions R.H.Lasseter University-of-Wisconsin

16 Micro Source Dynamics DC Bus AC Generator DC AC Type of Inverter Response of Prime Mover R.H.Lasseter University-of-Wisconsin

17 Inverter P-Q P Q response pu P & Q Line Commutated CSI - Line Commutated VSI - PWM with Voltage Linecontrol R.H.Lasseter Time seconds University-of-Wisconsin

18 20 sec R.H.Lasseter University-of-Wisconsin

19 Micro-Source Dynamics DC Bus AC Power Source DC AC Power Micro-turbine Fuel Cells seconds 0.0 R.H.Lasseter 10 time sec. 20 University-of-Wisconsin

20 Load Tracking Problem Power electronics Inertia-less system Fast response Instantaneous power balance Connect to grid Use storage on dc bus Storage on the ac bus Include rotating machines in Micro-grid R.H.Lasseter University-of-Wisconsin

21 Quality of Power Perspectives UTILITIES There are less than four interruptions per year with a cumulative interrupted average of less than 2-hours/year2 95 percent of interruptions are due to faults or outages on the T/D system 80 percent of the interruptions are due to distribution system components R.H.Lasseter CUSTOMER S Electricity problems disrupting equipment and production are originated by voltage sags, with duration less than 1/2 second There are about times per year that voltage sags occur with the voltage dropping below 70% Production equipment contains electronics sensitive to power quality problems University-of-Wisconsin

22 Micro-grid concept assumes: Large clusters of micro-sources and storage systems Close to loads with possible CHP applications Provide Quality of Power required by Customer Presented to the grid as a single controllable unit (load & source) R.H.Lasseter University-of-Wisconsin

23 Load Control using a Connected Micro Grid Load control Pload R.H.Lasseter Control P set point University-of-Wisconsin

24 Next 1. Problems and Issues related to Distribution Systems Power 2. Power Electronics Sources R.H.Lasseter University-of-Wisconsin

25 mgrid Operation and Control Problems and Issues Related to Distribution Systems A. P. Sakis Meliopoulos Georgia Institute of Technology Georgia Tech Tutorial 14 HICSS-34 Jan 3,

26 The mgrid Concept Distribution System Backbone Photovoltaics Interface Protection RTU Converter Micro-Grid Management System CATV& Communications RTU RTU Control Data Aqcuisition Sensitive Load RTU Fuel Cell Static Conditioner Variable Speed Drives Converter Interface Protection Interface Protection Converter Microturbine / Generator Georgia Tech 2

27 Distribution System Backbone Issues Safety Voltage Profile Power Quality Reliability Protection Unbalance/Asymmetry Stray Voltages and Currents Electromagnetic Compatibility Issues Non-autonomous/Autonomous Operation Georgia Tech 3

28 Safety Ventricular Fibrillation Let-Go Current (Milliamperes) - RMS Let-Go Current % Dangerous Current 50% 0.5% 20 Let-Go Threshold Safe Current Fibrillating Current (ma RMS) Kiselev Dogs Dogs Ferris Dogs sheep calves pigs Minimum Fibrillating Current (0.5%) Maximum Non-Fibrillating Current (0.5%) Body Weight (kg) Frequency (Hz) Georgia Tech 4

29 The Electrocution Parameters B A1 A2 r body B A1 A2 V eq Georgia Tech r eq 5

30 Applicable Standards (IEEE & IEC): Non-Fibrillating Body Current as a Function of Shock Duration Georgia Tech 6

31 Earth Current / GPR / Worst Case Condition Program XFM - Page 1 of 1 c:\wm aster\igs\datau\gpr_ex01 - May 14, 2000, 01:51: sam ples/sec Sam ples Phase_A_Line_Current BUS10 (ka) m m m Earth_Current G round_at_bus20 (ka) m m m m m m Georgia Tech Important Issues Grounding and Bonding Single Ground/Multi Ground Load/DER Configuration Transmission Interconnection 7

32 Power Quality Disturbances Design Options Georgia Tech Lightning Switching Power Faults Feeder Energization inrush currents, Motor Start Loading imbalance Harmonics, Resonance EMI Impact on End User Voltage Distortion, Sags, Swells, Outages and Imbalances Configuration Grounding Overvoltage Protection (arresters), Fault Protection Use of Steel/Aluminum conduit, Etc. 8

33 Lightning Caused Voltage Sags, Swells and Outages S w f S S A B C N d t D Georgia Tech 9

34 Lightning Caused Voltage Sags, Swells and Outages Effects of Grounding and Protection Georgia Tech 10

35 Voltage Sags & Swells and Grounding R 0 /X /173 95/164 Coefficient of Grounding /155 C g = V V actual LG no min al LG 2 85/147 80/ /129 70/ /100 65/117 Georgia Tech X 0 /X 1 11

36 Voltage Sags & Swells During a Ground Fault A A V A A V A V A A BUS10 BUS20 BUS30 BUS40 L R G V A Voltage (kv) Transmission Line Voltage & Current Profile Close Displayed Quantity Volt age Current _A _B _C _N BUS4 0 Distance (miles) BUS50 Program IGS - Form CODE_102A Georgia Tech Distribution Line, 12 kv Voltage Reference Nominal Voltage Remote Earth Neutral Ground 6.92 kv (L-L) Plot Mode Absolute Deviation Distance _A _B _C _N 0.00 Comments The Data of the Figure can be used to generate nomograms and statistical distributions of voltage sags and swells for a specific location (IEEE P1346) A better approach is outlined next V V A A 12

37 Statistical Distribution of Voltage Sags/Swells 4.0 Arrester Fuse Transformer L1 N L2 Sensitive Electronic Equipment G 3.0 Ground Rods Ground Loop Voltage (kv) 2.0 Probabilistic Approach to Power Quality Analysis 1.0 PQ Characterization Design Options for PQ Enhancement Georgia Tech Frequency (Hz) 13

38 Ferroresonance Maximum Overvoltage (pu) PHASES ENERGIZED 1 PHASE ENERGIZED Comments Resonance Between the Inductance of a Steel Core and the Circuit Capacitance Vulnerable Systems: Medium Voltage Cable with Transformers/Regulators Cases of Stuck Pole Single Phase Protection Capacitive/Inductive Impedance Ratio Georgia Tech 14

39 Harmonic Resonance BUS100 Comments Harmonic Resonance Has Multiple Modes and Resonance Frequencies BUS BUS40 BUS80 BUS90 BUS110 BUS120 System May Be Vulnerable When Resonance Coincides with a Harmonic Frequency BUS50 BUS60 BUS70 When Problem is Known, Solution is Very Simple - Detuning Frequency Scan At 2-Node Port: BUS70_A to BUS70_N Positive Sequence Frequency Scan at Bus BUS70/ P Magnit ude ( Ohms) Impedance Magnitude Frequency (Hz) Magnitude (Ohms) Magnit ude ( Ohms) Impedance Magnitude Frequency (Hz) Magnitude (Ohms) Frequency (Hz) Impedance Phase Table Frequency (Hz) Frequency (Hz) Impedance Phase Table Frequency (Hz) Phase ( Deg) Phase (Degrees) Phase ( Deg) Phase (Degrees) Frequency (Hz) Program WinIGS - Form FSCAN_RES Close Frequency (Hz) Program WinIGS - Form FSCAN_RES Close Georgia Tech 15

40 Reliability Reliability Indices for Distribution Systems (Utility Perspective) SAIFI: System Average Interruption Frequency Index (interruptions/year and customer) Total Number of Customer Interruptions per Year SAIFI = Total Number of Customers Served SAIDI: System Average Interruption Duration Index (hours/year and customer) Total Number of Customer Interruptions Durations per Year SAIDI = Total Number of Customers Served CAIDI: Customer Average Interruption Duration Index (hours/interruption) Total Number of Customer Interruption Durations per Year CAIDI = Total Number of Customer Interruptions Reliability Measures (Customer Perspective) Voltage Sags Voltage Swells Momentary Outages Load Interruption EMI Comments Good Methods for Utility Applications Exists (Markovian) ASAI: Average Service Availability Index Total Customer Hours Service Availability per Year ASAI = Customer Hours Service Demand Georgia Tech End User/DER Methods Needs Further Research (NonMarkovian Processes) 16

41 Cost of Reliability Example Power requirements: 3000 VA power Average power consumption is 2000 Watts Power utility reliability: SAIFI = 1.5, SAIDI = 45, Momentary = 30 Sector customer damage function: commercial per Table Below Calculations MWhrs consumed: Cost of two 20 minute outages: (3.0)(17.52)(2) = Cost of five 1 minute outages: (1.0)(17.52)(5) = Cost of momentary: (1.0)(17.52)(30) = Annual cost of interruptions: Comments Cost of utility power (assuming $0.10 pwr kwhr): $1,752 per year Survey of Cost of Interruption Sector Customer Damage Function ($/( $/MWhr) Sector\Duration Mom 1 Min 20 min 1 hr 4 hr 8 hr 24 hrs Residential Commercial Industrial Large User Georgia Tech 17

42 Reliability Research Issues Battery Energy = 15 min R R R Cap Prob Freq Dur 0 5e e-6 6 9e e Battery Energy = 30 min I I I Cap Prob Freq Dur 0 7.2e e-5 5 5e e Georgia Tech 18

43 Protection Typical DERs Protection Protection Issues Fault Protection (Current Limited DERs,, Remote Contribution, Ground Impedance, etc.) Faulted Circuit Indication Fault Location and Isolation Detection of Hot Down Conductors Georgia Tech 19

44 Unbalance/Asymmetry Most Power Circuits Are Asymmetric S 1 = 1 2 z max z 1 z min S 2 = 1 2 y max y 1 y min 0.06 Asymmetry Factor Series Admittance Shunt Admittance 0.0 Other Sources Frequency (Hz) Georgia Tech Single Phase Loads End Use Equipment Induction Motors 20

45 Induction Motor Response to Unbalance/Asymmetry Typical Distribution System Example Device Terminal Multimeter Close BUS100 Case: System Asymmetry and Imbalance Example BUS90 Device: Induction Motor BUS BUS40 Comments BUS80 BUS50 MCLOAD2 IM ANGSPEED2 BUS60 MCLOAD1 IM BUS ANGSPEED1 BUS110 BUS120 MCBUS1 Voltages MCLOAD1_A MCLOAD1_B MCLOAD1_C RGROUND Currents MCLOAD1_A MCLOAD1_B MCLOAD1_C Total Power Voltage Per Phase Power Current Va Vb Vc Ref Ia Ib Ic Va Ic Sa Sb IaS Sc Vc Ib Vb L-G L-L Phase Quantities Symmetric Comp P kw, Q kvar S = kva, PF = % Pa kw, Qa kvar Pb kw, Qb kvar Pc kw, Qc kvar Va = V, Deg Vb = V, Deg Vc = V, Deg Ia = A, Deg Ib = A, Deg Ic = A, Deg Combined Effects of System Component Asymmetry and Imbalanced Loads Program WinIGS - Form FDR_MULTIMETER Important Factors: Configuration Transformers Load Balancing Georgia Tech 21

46 Stray Voltages and Currents Sky Wire HA ~ I sky Comments HB HC ~ I neutral Neutral LA LB LC Single Phase Loads Generate Current Flow in the Parallel Path of Neutral and Soil/Grounds Ground Mat Counterpoise Ground Rod Ground Rod ~ I counterpoise ~ I earth Typical Distribution 50-70% in Neutral, 50-30% in Soil/Grounds CATV Neutral Voltage Typically 2 to 12 Volts Properly Designed mgrids can Practically Eliminate Stray Voltages and Currents Georgia Tech 22

47 Electromagnetic Compatibility Issues G SOURCE BUS10 BUS100 Example of Two Series Circuits in Magnetic and Aluminum Conduits BUS200 BUS400 Magnetic Field Near Nonmagnetic Conduit Enclosed Circuit Plot Circle Radius Feet 6.00 inches MilliGauss Plot Along Straight Line Plot Along Conduit Centered Circle Magnetic Field Return Update 1Ph 75.0 Magnetic Field Near Steel Conduit Enclosed Power Circuit (ID=3) Plot Circle Radius inches Feet Plot Along Straight Line Plot Along Conduit Centered Circle 76.0 Magnetic Field Return Update Angle (Degrees) Zoom In Zoom Out Zoom All Angle Field Program GEMI - Form EM F_CIRCLE Comments MilliGauss EMI can generate serious problems Georgia Tech Angle (Degrees) Zoom In Zoom Out Zoom All Angle Field Program GEM I - Form EM F_CIRCLE The mgrid concept offers an opportunity to rethink design issues and optimize EMI performance 23

48 WEMPEC Inverters in Microgrids Giri Venkataramanan Department of Electrical and Computer Engineering University of Wisconsin-Madison 3 Jan 2001 Giri@engr.wisc.edu 3 Jan 2001 Microgrids Short Course GV 1

49 WEMPEC Outline Description of inverter types and characteristics Inverter control objectives Inverter dynamic modeling Summary 3 Jan 2001 Microgrids Short Course GV 2

50 WEMPEC Inverter types PWM inverter Multilevel inverter Naturally commutated current source inverter 3 Jan 2001 Microgrids Short Course GV 3

51 WEMPEC PWM Synthesis A, B & C phases Vdc Va Vb Vc Phase shift between waveforms may be varied Amplitude of waveforms may be dissimilar All the three phase voltages could have an average Vdc/2 common mode voltage Causes a neutral shift Will cancel out in the line-line voltages 3 Jan 2001 Microgrids Short Course GV 4

52 WEMPEC Realization using IGBTs Vdc Va Vb Vc 3 Jan 2001 Microgrids Short Course GV 5

53 WEMPEC Multilevel Inverters Vdc + other phases Vdc Vdc + other phases Vdc 3 Jan 2001 Microgrids Short Course GV 6

54 WEMPEC Typical waveforms Pole voltage Vdc Vdc/2 Line-Line Voltage Stepped synthesis also possible 3 Jan 2001 Microgrids Short Course GV 7

55 WEMPEC Three Phase Current Source Inverter Two Pole Three Throw Switches Stiff Current 1P3T 1P3T 3 Jan 2001 Microgrids Short Course GV 8

56 WEMPEC CSI Converter Realization (Thyristors) Stiff current 1P3T Natural commutation Leading power factor load Three phase a voltages 1P3T 3 Jan 2001 Microgrids Short Course GV 9

57 WEMPEC 3 wire direct output DC voltage level has to be bigger than peak lineline voltage No path for zero sequence currents from inverter 3 Jan 2001 Microgrids Short Course GV 10

58 WEMPEC 4 wire interface using star-delta transformer DC voltage level free variable because of transformer turns ratio Zero sequence currents on star side circulates within the loop of the delta side 3 Jan 2001 Microgrids Short Course GV 11

59 WEMPEC Single line equivalent circuit and phasor diagram V i V i I L V o It I L I t V o V ac V ac Vac PCC voltage Vo Point of Load (POL) Voltage 3 Jan 2001 Microgrids Short Course GV 12

60 WEMPEC Microgrid Energy and Power Quality Management Functions Load profile control Source utilization Peak-shaving Reactive power injection POL voltage control Voltage imbalance correction 3 Jan 2001 Microgrids Short Course GV 13

61 WEMPEC Voltage sag correction Nominal condition V i I L I t V o V ac Operation under sag (Same real power transfer level) Operation under sag (Reduced real power to grid) 3 Jan 2001 Microgrids Short Course GV 14

62 WEMPEC Voltage imbalance correction Input voltage Brown Output voltage Cyan Phase currents Green Note increase in current stress on phases with large sag 3 Jan 2001 Microgrids Short Course GV 15

63 WEMPEC Fault Management V i I L I t V ac V o Fault 3 Jan 2001 Microgrids Short Course GV 16

64 WEMPEC Operation under transients Load transients System transients Capacitor switching Power quality events Delayed source response Islanding Reconnection 3 Jan 2001 Microgrids Short Course GV 17

65 WEMPEC Key Control Issues Power flow control Frequency control Local voltage control Reactive power control Power sharing Frequency matching 3 Jan 2001 Microgrids Short Course GV 18

66 WEMPEC Power throughput of inverter P = V ac X V t o sinδ Q = 2 o V X t VacV X t o cosδ Angle between V ac and V o determines power flow Magnitude of V o determines reactive power flow 3 Jan 2001 Microgrids Short Course GV 19

67 WEMPEC Modeling objectives Need to model dynamic properties Control input and real power flow or power angle Control input and reactive power flow or voltage magnitude 3 Jan 2001 Microgrids Short Course GV 20

68 WEMPEC Typical controller structure (classical) + V ac Voltage command + - Voltage Controller + - Current Regulator Current feedback PWM Converter and LC Filter V o V i I L - 1 L s I t Voltage feeback 3 Jan 2001 Microgrids Short Course GV 21

69 WEMPEC Typical controller structure Flux vector + V ac Flux command + - Flux Regulator PWM Converter and LC Filter V o V i - 1 L s I t Flux feedback λ i 1 s V i I L V o It λ i V ac 3 Jan 2001 Microgrids Short Course GV 22

70 WEMPEC Key control variables Magnitude and Phase angle Modulation input Inverter output Filter inductor current output Capacitor voltage output 3 Jan 2001 Microgrids Short Course GV 23

71 3 Jan 2001 WEMPEC GV 24 Microgrids Short Course Key control variables ) ( ) ( ) ( t m j e m t m t = ) ( ) ( ) ( t v j i i i e t v t v = ) ( ) ( ) ( t i j L L L e t i t i = ) ( ) ( ) ( t v j o o o e t v t v = Instantaneous phase quantities are projections of the rotating vectors on appropriate axes

72 WEMPEC d L i dt d L il dt C L = i d dt C v o v L v dc o d dt = Dynamic Equations m v dc cos( m i L ) m sin( m i L v o ) = i cos( i v ) L L o cos( v v v o R v = i sin( i v ) o L L o o o sin( v v o R i o L ) i L ) 3 Jan 2001 Microgrids Short Course GV 25

73 WEMPEC Steady state operating condition 0 = Vdc M cos( M I L ) Vo cos( Vo Io ) L I L ω = V dc M sin( M I L ) V o sin( V o I L ) 0 = I cos( I V ) C V o L L o V o R ω = I sin( I V ) L L o V o R 3 Jan 2001 Microgrids Short Course GV 26

74 WEMPEC Steady state operating condition 0 = V M cos( φ ) dc mi L V o cosφ v o i L L I L ω = V dc M sinφ 0 = I cosφ L C V o L i V R mi ω = I sinφ L L v o i v o o L V o R V o sinφ v o i L Classical phasor solution 3 Jan 2001 Microgrids Short Course GV 27

75 3 Jan 2001 WEMPEC GV 28 Microgrids Short Course Small signal model at operating point Fu Ex y Bu Ax x + = + &= = RC V RC I V RC V RC I V LR I V L I C V I L I C V LR I V I A o L o o L o L o L o L L o L o L ω ω ω ω ω ω ω ω = 0 0 sin cos L mi dc mi dc L I V L V B L L φ φ = o o L L v v i i x ~ ~ ~ ~ m u ~ =

76 WEMPEC Transfer function Magnitude of modulation to output voltage 60 MG( f k ) f k 0 AG( f k ) 90 3 Jan f k Microgrids Short Course GV 29

77 WEMPEC Perturbations in time domain 200 Voac( t, 1000) Voa( t, 1000) t 1000 Ioa( t, 1000) Ioac( t, 1000) t Jan 2001 Microgrids Short Course GV 30

78 WEMPEC Vectors on the Complex Plane Im( Vocomplex( t, 1000) ) Re( Vocomplex( t, 1000) ) Output current complex vector Im( Iocomplex( t, 500) ) 0 3 Jan 2001 Microgrids Short Course Re( Iocomplex( t, 500) ) GV 31

79 WEMPEC Properties of the dynamic model Eigen frequencies of small signal model i i i i Eigen frequencies of LC filter = 569 Hz (incl. damping effects) Excitation frequency = 60 Hz 3 Jan 2001 Microgrids Short Course GV 32

80 WEMPEC Dynamic interaction issues Angle input to output transfer functions Cross coupling transfer functions Selection of controllers and tuning Outer loop effects (Real and reactive power, droop, etc.) Frequency synchronization Interactions between multiple parallel units EMI filter interactions 3 Jan 2001 Microgrids Short Course GV 33

81 WEMPEC Summary Inverter modeling important aspect of microgrid design Stiff dc bus with adequate storage decouples prime mover dynamics Inverter dynamic model based on rotating vectors Model reduces to phasor model at steady state Small signal model properties outlined Various transfer functions can be determined, (esp. angle and frequency) Extend and integrate into system models 3 Jan 2001 Microgrids Short Course GV 34

82 Operation and Control of Micro-Grids Robert H. Lasseter University of Wisconsin R.H.Lasseter University-of-Wisconsin

83 Micro-grid concept assumes: Large clusters of micro-sources and storage systems Close to loads with possible CHP applications Customer Quality of Power Presented to the grid as a single controllable unit (load & source) R.H.Lasseter University-of-Wisconsin

84 Micro Grid open Solid state breaker Generation & storage Motor Loads 13.8 kv 480V 480V V 8 M5 9 M8 M9 R.H.Lasseter University-of-Wisconsin

85 Control of P &Q using PWM Inverters Vinv E Inverter P δ p0 Q V inv δ 0 Vinv E R.H.Lasseter University-of-Wisconsin

86 Basic P Q Controller V a V b V c E a E b E c Flux Vector Calculator Flux Vector Calculator ψ v δ v ψ E δ E ψ v o Inverter Flux Vector Control δ P o Inverter Switch r e I a I b I c E a E b E c P & Q Calculation P Q P o + + Q o p-i p-i δ P o ψ v o R.H.Lasseter University-of-Wisconsin

87 Basic P & Q Response P Current Q R.H.Lasseter University-of-Wisconsin

88 Micro Grid connected to T/D Grid Micro-Sources Provide Control of local bus voltage Control of base power flow Fast Load tracking is provided by the grid Micro Grid: Dispatchable load to the grid R.H.Lasseter University-of-Wisconsin

89 Micro Grid P control V control of 8 & kv 480V V 480V 8 M5 9 M8 M9 R.H.Lasseter University-of-Wisconsin

90 P V controller 8 on Bus 8 Bus 9 9 on R.H.Lasseter University-of-Wisconsin

91 Isolated Micro Grid Issues Instantaneous power balance Use storage on dc bus Storage on the ac bus Include rotating machines in Micro-grid Load Sharing Frequency Control R.H.Lasseter University-of-Wisconsin

92 Island System P ~ Sin( ) δ2 δ 1 V / δ 2 V/ 2 1 δ 1 L 2 Increase L 2 L 1 R.H.Lasseter University-of-Wisconsin

93 P ~ Sin( δ1 δ2) ω 0 > ω 1 > ω 2 ω 0 V 1 V 2 δ 2 R.H.Lasseter University-of-Wisconsin

94 Frequency Droop ω P 02 P 01 ω o ω 1 ω min P P 2max P 1max R.H.Lasseter University-of-Wisconsin

95 Power Droop ω i (t) =ω 0 m i (P c,i P i (t)) ω o ω + + _ s k" s k' P c + _ + P _ m _ δ E 1 s + + _ p-i - δ P o P o R.H.Lasseter University-of-Wisconsin

96 P V Controller with Droop E I E 0 P & Q Calculation ω o P o 1 ω Q P ω E V s ψ Eo Flux Vector Calculation Power with droop + _ δ E ψ E ψ v δ v I p-i Inverter Flux Vector Control ψ v o δ P o R.H.Lasseter University-of-Wisconsin

97 Island Micro Grid open Solid state breaker Generation & storage Motor Loads 13.8 kv 480V 5 Non-critical Loads 6 480V 480V 8 M8 M5 Critical Loads 9 M9 Critical Loads R.H.Lasseter University-of-Wisconsin

98 Voltage on Buses 8 & 9 R.H.Lasseter University-of-Wisconsin

99 Injected P & Q Buses 8 & 9 R.H.Lasseter University-of-Wisconsin

100 Frequency Droop ω P 02 P 01 ω o ω 1 ω min P P 2max P 1max R.H.Lasseter University-of-Wisconsin

101 Frequency at bus 8 Frequency Hz Time seconds R.H.Lasseter University-of-Wisconsin

102 Sensitive loads (Quality & Service) Power Quality is the attribute of electric power which enables utility customers electrical and electronic equipment to operate as intended R.H.Lasseter University-of-Wisconsin

103 Voltage Sensitivity cycles 100 CBEMA R.H.Lasseter 50 0 Type 1 CBEMA Type Durat ion (6 0 Hz Cycles) University-of-Wisconsin

104 Shunt current injection 1.0 Voltage Sag 1.0 Restored Voltage injected current Critical Load R.H.Lasseter University-of-Wisconsin

105 Premium Power Micro Source Power UPS Power Source Voltage control unbalance frequency DC DC AC DC R.H.Lasseter University-of-Wisconsin

106 Voltage Sag Regulator abc - V d dq V -* s =0 Negative component - - V V s c PID dq- dq- - V q Ø s - dq abc V s abc + V d dq V s + V s + * PID V c + dq+ Inverter - dq+ + V q Ø s + dq abc R.H.Lasseter Positive component University-of-Wisconsin

107 Inverter Response to SLG R.H.Lasseter University-of-Wisconsin

108 Micro Grids & Premium Power Generation Close to loads Local reliability Possible CHP applications Premium Power UPS functions Back-up service Custom Power functions R.H.Lasseter University-of-Wisconsin

109 Research Needs 1. Clear interfaces/functions to the Grid 2. Micro-Grid protection 3. Plug & play controls 4. Placement tools including CHP. R.H.Lasseter University-of-Wisconsin