Operation and Control Microgrid and Distributed Generation. Mohammad Shahidehpour Illinois Institute of Technology

Transcription

1 Operation and Control Microgrid and Distributed Generation Mohammad Shahidehpour Illinois Institute of Technology

2 Outline Introduction - Microgrids High Reliability Distribution Systems Perfect Power System IIT Microgrid Optimal Control of Microgrid Reliability Evaluation Stochastic Solution Islanding and Synchronization 2

3 Introduction Microgrids Microgrids are considered as viable options for electrification where the main grid expansion is either impossible or has no economical justification. The decentralized operation and control of microgrids could also reduce the transmission burden on power utility systems. 3

4 Introduction Microgrids Microgrids can provide higher reliability and power quality for loads. Once in grid- connected mode, any grid failure will lead to microgrid islanding. In the island mode, the master controller relies on microgrid generation and storage to serve the microgrid load and prevent curtailments. The load restoration procedure in microgrids could depend on the reliability requirements of loads. Microgrid topology could play a crucial role in supplying microgrid loads with diverse reliability requirements. 4

5 DER in Microgrids Distributed energy resources (DER) in a microgrid would include photovoltaic (PV), small wind turbines (WT), heat or electricity storage, combined heat and power (CHP), and controllable loads. DER applications would increase the efficiency of energy supply and reduce the electricity delivery cost and carbon footprint in a microgrid. DER applications would also make it possible to impose intentional islanding in microgrids. The proximity of generation to loads in microgrids would improve the power quality and reliability (PQR) at load points. 5

6 Storage in Microgrid Storage devices including batteries, supercapacitors, and flywheels could be used to match generation with demand in microgrids. Storage can supply generation deficiencies, reduce load surges by providing ride-through capability for short periods, reduce network losses, and improve the protection system by contributing to fault currents. V2G and EV mobility can reduce the microgrid reliance on the grid supply. 6

7 Introduction Control Devices Hierarchical control performed by master controller ensures the economical and secure operation of microgrids by maintaining the frequency and voltage in microgrids. Master controller uses SCADA to monitor and regulate frequency and voltage in microgrids according to P-f and Q-V droop characteristics. IIT microgrid is considered as a test-bed to evaluate the effects of intelligent switching and storage implementation on reliability and economic operation of microgrid. 7

8 High Reliability Distribution System (HRDS) Implementation of microgrid loops is made possible by the use of automatic switches in HRDS. HRDS switches can sense the cable faults and isolate the faulted section with no impact on other sections in a microgrid. Master controller will monitor the status of each HRDS switch using the supervisory control and data acquisition (SCADA) system. Master controller is responsible for economic operation of the microgrid based on signals received from switches on the status of distribution branches. 8

9 HRDS vs. No HRDS HRDS vs. No HRDS No HRDS S15 S16 HRDS 9

10 Problem Formulation Random outages of grid-connection facilities, microgrid DG, and microgrid distribution lines are considered. Monte Carlo representation of outages is applied and the Latin Hypercube Sampling (LHS) technique is used to develop a large number of scenarios with equal probabilities. A two-state Markov chain process is utilized to represent microgrid outages according to the microgrid component failure and repair rates. Since the computation time of stochastic optimization is dependent on the number of scenarios, the scenario reduction technique is utilized to reduce the number of generated scenarios to an acceptable level with the corresponding probabilities. 10

11 Master Controller Formulation Stochastic Formulation s s s s F, (, ),, ci Pit SUit SDit s t i Min p s s Ds, ds, t Pg, t VOLL.( P,, ) bt Pbt t b it s, gt s, kt s, Dt s, k s s s it, i it, it, 1 P P P P i SU CS ( I I ) s s s it, i it, 1 it, SD CD ( I I ) min s s s max s s i i, t i, t i, t i i, t i, t P UX I P P UX I min s s max s g g, t g, t g g, t P UX P P UX 11

12 Problem Formulation net, s s s kt, dckt,, k ckt,, E P P s s s kt, dckt,, ckt,, P P P I s s dc, k, t Ic, k, t 1 s min s s max c, k, t c, k c, k, t c, k, t c, k I P P I P s min s s max dckt,, dck, dckt,, dckt,, dck, I P P I P min s s max s s k dckt,, ckt,, kt, k dckt,, ckt,, Q ( I I ) Q Q ( I I ) s s net, s kt, kt, 1 kt, E E E min s max k k, t k E E E E E k,0 k, NT 12

13 Problem Formulation s s s d, s inj, s P it, P gt, P kt, P Dt, P j, t i g k d i D g D k D d D j j j j s s s d, s inj, s Q it, Q gt, Q kt, Q Dt, Q j, t i g k d i D g D k D d D j j j j ts, ts, r,,, oj, Uo, j xoj, U ts ts ts o, j oj, oj, oj, ro, j xo, j ro, j xo, j y g jb j 13

14 Problem Formulation P ( V ) G inj, s s 2 t, s jt, jt, j, j NB s s t, s s s t, s s s Vj, t Vo, t[ Gj, ocos( j, t o, t) Bj, osin( j, t o, t)] o( j o) NB inj, s s t, s t, s s s t, s s s Pj, t Vj, t Gj, j Gj, o Vj, t Vo, t Bj, o j, t o, t o( j o) inj, s s 2 t, s Qjt, ( Vjt, ) Bji, NB o( j o) (2 1) ( 1) ( ) V V [ G sin( ) B cos( )] s s ts, s s ts, s s j, t o, t j, o j, t o, t j, o j, t o, t NB injs, s ts, ts, s s ts, s s j, t j, t j, j j, o j, t o, t j, o j, t o, t o( j o) Q (2V 1) B B ( V V 1) G ( ) 14

15 Problem Formulation PL ( V ) G ( QL ) ( PL ) ( SL ) SL ts, s 2 ts, jo, jt, j, j V V [ G cos( ) B sin( )] s s t, s s s t, s s s j, t o, t j, o j, t o, t j, o j, t o, t PL G ( V V ) B ( ) ts, ts, ts, ts, ts, ts, ts, jo, jo, j o jo, j o QL ( V ) B ts, s 2 ts, jo, jt, j, j V V [ G sin( ) B cos( )] s s ts, s s ts, s s j, t o, t j, o j, t o, t j, o j, t o, t QL B ( V V ) G ( ) ts, ts, ts, ts, ts, ts, ts, jo, jo, o j jo, j o ts, 2 ts, 2 ts, 2 jo, jo, jo, SL PL QL ts, ts, ts, ts, jo, jo, jo, jo, SL ts, max jo, jo, 15

16 Perfect Power System IIT Microgrid 16

17 Perfect Power System IIT Microgrid 17

18 Perfect Power System IIT Microgrid 18

19 Perfect Power System IIT Microgrid IIT demand is supplied by three KV circuits fed from the Fisk substation that is owned by ComEd. The peak load at IIT is approximately 10 MW. 19

20 Perfect Power System Components Renewable energy sources include wind and solar generation. An 8 kw Viryd wind turbine is installed on the north side of the campus in Stuart soccer field. PV cells will be installed on building rooftops to supply portions of campus load. A 500-kWh ZBB storage will increase the reliability and efficiency of the microgrid. Several electric vehicle charging stations will be deployed on campus, facilitating small energy storage and providing green energy for electric vehicles. 20

21 Perfect Power System Components 6 five hour charging stations 1 DC Quick Charge (15 20 minutes) FREE Charging for Electric Vehicles (for now) 21

22 Perfect Power System Components 22

23 Perfect Power System Components 23

24 Perfect Power System Components Energy Efficiency Demand Response Islanding Mode Real time information 24

25 Perfect Power System IPPSC Intelligent Perfect Power System Controller (IPPSC) IPPSC manages the campus electricity distribution system and electricity usage. IPPSC utilizes SCADA at all hours for reliable and economic operations of microgrid. IPPSC coordinates HRDS controllers, on-site generation, storage facilities and building controllers. Intelligent switching and advanced coordination technologies through communication systems facilitates rapid fault assessment and isolation 25

26 Microgrid Reliability Evaluation Study Cases : Case 1: IIT network is not equipped with HRDS switches Case 2: IIT network is equipped with HRDS switches Case 3: IIT is equipped with HRDS switches and a storage Hermann Hall (kwh) Siegel Hall (kwh) Wishnick Hall (kwh) Perlstein Hall (kwh) Total (kwh) Case Case Case

27 Reliability Evaluation Stochastic Solution The installation of HRDS and storage will lead to the best expected reliability and economic indices. Case No HRDS HRDS HRDS + Storage Exp. SAIDI Exp. SAIFI Exp. CAIDI Exp. CAIFI Exp. Operation Cost 224, , ,038 Exp. Energy not Supplied 1, LOLE

28 Optimal Control of Microgrid Power (kw) Main grid supply Battery supply Total Demand Main grid price Time (Hours) Electricity Price ( /kwh) 28

29 Optimal Control of Microgrid Power (kw) Grid Dispatch Power Plant Dispatch Price Time (Hours) Electricity Price ( /kwh) 29

30 Islanding and Synchronization 30

31 Microgrid Fault Analysis No HRDS Fault takes 30 cycles to clear. The system is radial. Once the breaker opens, all the loads downstream will be disconnected. HRDS Fault takes 6 cycles to clear. The system is loop. Once the breakers open, only the faulted cable is isolated. 31

32 Fault Simulation Relative Voltage Angle of Gen. 2- No HRDS Gen. 2 Relative Angle (degree) Time (second) 32

33 Fault Simulation Relative Voltage Angle of Gen. 2 - HRDS Relative Angle (degree) Gen Time (Second) 33

34 Building Restoration Sequence Building Restoration Sequence: T=30 sec T=45 sec T=60 sec T=75 sec T=85 sec 3410 Central CTA Facility Perlstein Hall Stuart Bldg. IIT Tower 3424 Central Cunningham Quad TBC Incubator Alumni Hall Eng1 S.R. Crown TS3424 Keating Carman Galvin Siegel Hall Vandercook Life Science Carr Gunsaulus Metal S.1 Whishnick Life Science Research MTCC Hermann Hall Metal S. 2 SSV Main Metal N. 34

35 Load Restoration Demand (MW) Alumni Hall Life Science Research Wishnick Hall Siegel Hall Engineering Time (Second) 35

36 Load Sharing Among Generators 8 6 Gen 1 Gen 2 Load Increment Power (MW) Time (Second) 36

37 Synchronization (frequency check) Freq. Deviation < 1 Hz Frequency (Hz) Time (Second) 37

38 Synchronization (voltage angle check) Voltage Angle (degree) Voltage Angle Diff. < 30⁰ North SS South SS Time (Second) 38

39 Synchronization (voltage check) Voltage Diff. at switching instance North SS Voltage (kv) Time (Second) 39

40 Conclusion and Summary Application of HRDS, local generation, and storage is presented and the reliability and economic evaluation of microgrid is evaluated: AC formulation is offered to solve the unit commitment and economic dispatch in microgrids. Integration of HRDS and evaluation of reliability and economic indices of microgrids are considered as compared to those in traditional distribution systems. Provision of stochastic solution to two proposed topologies is considered for the comparison of reliability indices. Assessment of the role of energy storage on the economic operation of microgrids is considered and improved reliability indices at load points are calculated. 40

41 Conclusion and Summary HRDS will clear the fault faster and has less effect on the stability of the system specially in islanded mode Once islanded, the local generation will maintain the frequency and voltage of the system. In order to synchronize with the main grid, frequency deviation, voltage deviation and voltage angle deviation should be within the acceptable limits. Two generators will share the loads based on their droop characteristics. Once the first generator reaches its maximum capacity the second generator would maintain the frequency of the system by providing enough active power. 41

42 Conclusion and Summary HRDS and automatic switches can reduce the expected frequency and duration of interruptions and the expected energy not supplied in the system. Storage can reduce the operation cost of the system by demand response and preventing load curtailments. Local generation helps mitigate the expected interruption duration and frequency in the system and improve the reliability of the customers in microgrid. 42