China-US S&T Strategic Policy Workshop on Smart Grid Analyses and Control of the Bulk Power System based on Synchronized Phasor Measurement System

Transcription

1 China-US S&T Strategic Policy Workshop on Smart Grid Analyses and Control of the Bulk Power System based on Synchronized Phasor Measurement System Yingduo Han, Chao Lu Dept. of EE, Tsinghua Univ. 5/30/2013, Washington DC 1

2 Outlines PMU/WAMS Developments Two Typical Applications based PMU/WAMS Roadmap and Future Work about PMU/WAMS Applications New Thoughts based on Smart Grid Concepts 2

3 1. Current PMU Locations and Plan in North American 3

4 PMU/WAMS Deployed in China PMUs were installed in more than 1500 substations and power plans. (12/12) Northwest:272 North:312 Northeast:291 WAMS master stations are deployed in all provincial dispatch centers (>40). Central:341 East:147 4

5 PMU/WAMS based Applications in China Advanced Control & Protection Decision Support Wide-area Monitoring Wide-area visualization Disturbance detection Offline disturbance analysis Oscillation detection Frequency regulation monitoring Stability Alarming Voltage/angle/frequency trending and Stability alarming Oscillation identification and alarming Transient stability assessment and optimization Oscillation related power flow optimization Steady state stability assessment and decision optimization Online model & parameter identification Renewable energy integration wide-area control Transient/voltage stability coordinated control Planned system separation Oscillation source control Wide-area Damping control Angle/frequency/voltage/flow monitoring Improved or linear state estimation Advanced remedial actions and protections Technical challenging 5

6 Case 1: Northeast China Power System Large Disturbances Field Tests (2003) 500kV substation bus, artificial three-phase grounding short circuit

7 Monitoring using PMU in master stations 7

8 Simulation Model and Parameter Modification according to PMU Recordings Load Model and Parameters East HLJ Power Transfer Limit(MW) HLJ to JL Limit (MW) JL to LN Limit (MW) Group 1 Group 2 Group 3 Group Group 1:50% constant impedance+50% motor Group 2:40% constant impedance+60% constant power Group:the motor stator impedance is changed from to 0.12 Group 4:IEEE-6 type motor 8

9 Online Dominant Load Parameters Identification Dominant parameter selection Steady state measurement online Dynamic state measurement State equation to Volterra model Eigenvector matrix Reduced order Volterra model based LS K-L orthogonal transform Projection direction and classification boundary Online fast pattern recognition offline Pattern classification Model Para. Online analysis and control 9

10 Case 2: Wide-area Close Loop Damping Control in China Southern Power Grid The Chinese power grid includes about 30 provincial systems, and most of them are connected through 500kV AC lines. After region grids interconnection, the weakly damped low frequency oscillation becomes the bottleneck of improving system transfer capacity. Increasing the PSSs can not solve this problem substantially. The oscillation lasted 5 minutes, and the amplitude reached 730MW. (Middle China Power Grid, ) The oscillation lasted 3 minutes, and the amplitude reached 120MW. (China Southern Power Grid, ) 10

11 GPS/Beidou Mode 1 Mode 2 Key issues: 1. AC/DC interconnected system damping control strategies; 2. Wide-area controller structure design; 3. Multiple damping controllers coordination; 4. Time delay induced new oscillation modes analysis; 5. Wide-area random time delay adaptive compenstation. 11

12 Close Loop Time Delay Distributions PMU Control center Control substation, transmission distance: >2000km Multiple 2M channels and UDP protocol were used to reduce delay. Mean value: 67.03ms More than 98.7% is distributed in the range of 60~75ms. The delay is mainly composed by phasor measurement and calculation( 30ms), signal transmission ( 20ms) and calculation in the main station ( 10ms). Counts in 2 hours Time Delay (ms) 12

13 Time Delay induced New Oscillation Mode Active power on the 500kV line (MW) Time delay: 50~60ms Gain: K=5 Time (seconds) Frequency: 5~6Hz 13

14 Practical HVDC pole/station control/protection cubicles RTDS Tests PMU cubicles Control substation cubicles RTDS(10 Racks) Power Amplifi 14

15 3.5 Large Disturbances Field Tests Results -400 With WHDC Relative angle between Yunan and Guizhou 贵州 云南相对功角 ( 度 ) Mode 1 高肇直流协调控制投入高肇 兴安直流协调控制投入协调控制退出 时间 (s) Without WHDC Disturbances: multiple HVDC monopole blocks (700MW), 500kV key inter-area tie-line tripping and closing; The damping ratio can be improved from 7.5% to 20.5%, and the transfer power limit can be enhanced more than 650MW. Active power on the 500kV line (MW) 梧罗线功率 (MW) Time 时间 (seconds) ( 秒 ) 高肇调制控制单独投入协调控制系统投入协调控制系统退出 Modes 1&2 15

16 Our Group s Roadmap Developing new EMS based on PMU/WAMS PMU algorithm and device R&D WAMS framework design and system Implementation Wide-area damping control system Dominant load parameters identification Wide-area EMS framework design Power system state measurement New excitation and identification device Multiple levels load identification Typical W-EMS application demonstration W-EMS experimental platform based on fast simulation Complete W-EMS system implementation including dynamic power flow, important parameters or reduced-order system identification, steady and dynamic stability assessment and alarming, real time decision and close-loop control, all based on improved PMU/WAMS or AMI 16

17 New Thoughts from the Smart Grid Concepts Traditionally, the power balance is highly dependent on the spinning reserve, and the redundancy may cause huge wastes. If the information and demanding responses are fully invloved, the power system design and operation will be changed completely. The information can be delivered in nearly real time (ms), so the constraints about unobservability and uncontrollability can be relaxed, and then the conventional local or trial-and-error controllers can be all redesigned. In addition, with the employment of identification techniques, the problems of randomness and time-varying characteristics of some important power system parameters can be solved. The cost of increasing conservativeness for more reliability may be saved. 17

18 清华大学 Thanks for your attentions!

19 Future Trends about PMU/WAMS Smart grid development will accelerate PMU/WAMS applications; Dynamic state estimation based on more reliable and precise PMU/WAMS will be the foundation for new generation of EMS; Power system model and parameters can be identified and calibrated online in the near future; Innovative power system measurement, identification, analysis and control theory can be developed based on emerging information technologies applications. 19