AC/DC system interac6ons and control Fault clearing in MTDC networks

Transcription

1 SCCER FURIES AC/DC system interac6ons and control Fault clearing in MTDC networks Lausanne, 15 th December 2014 WP3 Academic Members:

2 WP3: Research challenges in MT AC-DC grids and power electronics New (MT- ) DC connec>ons are added to the European transmission system. Their effect on the system cannot be neglected in the future. Key challenge 1: AC / DC system interface Future DC transmission systems are embedded into the AC system and interconnected. Fault events cannot be managed independently. Key challenge 2: fault management concept The failure of DC transmission or power electronic equipment will have more significance in the future Key challenge 3: fault clearing and post- fault opera6on Innova>ve solu>ons are needed for the large- scale deployment of power electronic solu>ons in transmission and distribu>on Key challenge 4: systems and materials for power electronic building blocks 2

3 WP3 Academic Partners ETH Zurich High Power Electronic Systems (Prof. Jürgen Biela) Power Electronic Systems Laboratory (Prof. Johann Walter Kolar) High Voltage Laboratory (Prof. Chris>an M. Franck) EPFL Lausanne Power Electronics Laboratory (Prof. Alfred Rufer; Prof. Drazen Dujic) Distributed Electrical Systems Laboratory (Prof. Mario Paolone) HES- SO Ins>tute for Energy and Electrical Systems, HEIG- VD (M. Carpita) Energy Ins>tute, EIA- FR (P. Favre- Perrod) 3

4 AC/DC system interactions and control 4

5 Introduction ACDC system interaction Motivation Increasing share of power flows controllable VSC technology widely used Previous work Static interactions: Power flow optimisation, voltage stability improvement,... Dynamic interactions: damping of oscillations, improvement of angular stability,... (e.g. ETH Zurich / Swisselectric research) Challenges Evolving characteristics of AC and DC systems Multi-terminal DC systems (?) 5

6 FURIES Approach AC/DC system interaction Implications on system development / operation Harmonics in AC systems System services provided by MTDC terminals Project "AC/DC system interactions" Requirements on converters / technologies Investigate design and control aspects related to converter for the provision of services to the AC system Project "AC/DC system models and converter studies" 6

7 Project "AC/DC system interactions" Project objectives: Establish harmonic models for typical NL1 and 3 networks Investigate resonances for increased power electronic converter usage and higher shares of cables in the network Investigate AC/DC mutual influence on stability and services Project activities (Jan-Dec 2014): Resonances: Models established / Coupling of NL1 and 3 investigated Project results: Models Partners Academic: HES-SO Fribourg + Yverdon Industrial: EOS Holding (technical support from Swissgrid) 7

8 Key achievements Harmonic model of realis6c NL1 and 3 networks Coupling of NL1 and 3: influence of cable links Overhead Lines and Underground Cable (Line 3-5) at Level 1 Overhead Lines and Underground Cables (Lines 2-3 and 3-5) at Level 3 8

9 Methods Interconnec>on of the transmission system levels Level1 Level3 u : Y $$ Y $%... Y %$ Y %% + Y " u Y "... u Y " Y ** + u % Y " Y *+ Y *,.. Y +* Y ++ Y +,.. Y,* Y,+ Y,, 9

10 Methods Impact of one Level on another Level u :

11 Consequences for network development Overhead Lines Transmission System Introduc>on of the underground cables into the network reduces resonance peak frequency Mixed Transmission System (Overhead Lines and Underground cables) 11

12 Consequences of renewables integration Harmonic s Injec7on u : Network Level 1 Network Level 3 Harmonics injec>ons in Network Level 3 influence on the power system parameters at Network Level 1 12

13 Examples Three examples: 10 bus power system SwissGrid Power System (164 buses) SwissGrid Groupe E Power System (194 buses) 13

14 Examples 10 bus power system Frequency Scan 14

15 Examples 10 bus power system Frequency Scan Underground Cables Overhead Lines and Underground Cable (Line 3-5) at Level 1 Overhead Lines and Underground Cables (Lines 2-3 and 3-5) at Level 3 15

16 Examples SwissGrid Groupe E Power System (194 buses) 380 kv 220 kv 60kV 16

17 Examples SwissGrid Groupe E Power System (194 buses) Frequency Scan 380kV 220kV 60kV 17

18 Next steps Complete study of resonances Launch phase 2: AC/DC stability and services interaction Integration of project results into: MSE course (HES-SO) CAS course in planning (EIA-FR) 18

19 AC/DC system models and converter studies (internal) Status: Project started, industrial funding to be found Project objectives: Implement a small scale prototype of MMC to be used in a Minigrid for studying AC/DC systems interaction To establish a structure adapted to the medium voltage (5-10kV) based on the MMC approach, devoted to distribution networks in cities or industrial areas Evaluate the functionning of MMC as energy buffer for network support and reactive compensation. Project activities (Jan-Dec 2014): Design, realisation and test of the first prototype of a full-bridge 1kV-10A module Design of the control system and boards 2 Diploma thesis ongoing Project results: First 1kV-10A Module Prototype, Partners Academic: HES-SO Yverdon Industrial: t.b.d. 19

20 Key achievements MMC principle 1kV- 10A board prototype Control system principle MAIN CONTROL Voltage reference ARM CONTROLLER OPTIC FIVER - Current interface - Grid interface - Energy controller (ARM) Total voltage Individual voltages MODULATOR TO MODULES TO MODULES MODULE 1 SORTING N=4,6,8 COUNTING ARM CURRENT SENSORS MODULE N ARM CONTROLLER (MAX6) 20

21 Next steps Complete the design of the control system Build a single-phase demonstrator Development of the control strategies for the current injection and the management of the MV intermediary energies (up to 4kV) Use of MMC for grid injection of photovoltaic and energy storage (AP Energy grant ongoing) 21

22 Fault clearing in MTDC networks 22

23 Introduction Fault-clearing in MTDC networks AC- Side Fault- clearing DC- Side With interrup>on of supply Without interrup>on Fault- blocking converters Sta>c DC breakers Mechanical Hybrid Fault detec>on "Coordinated" (with communica>on) Local Differen>al protec>on... Overcurrent, undervoltage... "Distance" protec>on for HVDC Analysis of fast transient voltages/currents 23

24 FURIES Approach Fault-clearing in MTDC networks Prepare and qualify devices for DC fault management Investigate DC breaker concepts Project "Limit performance of different HVDC CB concepts" Prepare adequate testing facilities Project "High-current DC testing" Provide fast and reliable fault-detection for DC grids Project "Fast detection and location of DC faults in multi-terminal networks" 24

25 Project limit performance of different HVDC CB concepts Project activities (Jan-Dec 2014): Characterisation of switching arc in HVDC CBs Simulation of different HVDC CB technologies in multiteminal networks (this activity is added to the original plan, work of redirected PhD student in replacement of PostDoc) Project results: Method of characterisation of switching arcs ready, accuracy improved and first measurements with model circuit breaker performed Simulation of different HVDC CB technologies ready, publication in preparation. Partners Industrial: ABB CRC Switzerland 25

26 Key achievements High accuracy tes>ng of swiching arcs for HVDC CBs with pulsed current source possible. Evalua>on methods improved, especially for thermal arc inter>a Systema>c evalua>on of arcs under different external stresses on- going. P1(g1) P1(g1) P2(g2) τ1(g1) τ2(g2) 26 τ1(g1) P2(g2) τ2(g2)

27 Key achievements Simula>on model of different HVDC CB technologies in four terminal network implemented: full solid state, pure mechanical (ac>ve and passive resonance), hybrid. Short circuit current levels and voltage evolu>on simulated Influence of network and protec>on parameters inves>gated. 27

28 Next steps Physical understanding of switching arc characteristics (maybe new diagnostic tools required) Limit performance of different CB technologies to be evaluated. 28

29 Project "Fast detection and location of DC faults in multi-terminal networks" Project objectives: contribution to milestone Faultmanagement processes and AC/DC co-ordination recommendations Project activities (Jan-Dec 2014): proof-of-concept of the applicability of the time-reversal process to locate fault in multi-terminal HVDC networks Project results: publication at the PSCC 2014 Partners Academic: EPFL-DESL, EPFL-EMC Lab Industrial: none Other support (EU, CTI, etc.): SNSF project Power Networks Fault Location based on Electronic Emulation, collaboration with the G2ELab of the Univ. Grenoble Alpes, France within the context of the FP7 project Twenties. 29

30 Key achievements Mul6- terminal HVDC networks (TWENTIES project) Fault Current Energy [Normalized] p2p solid fault at xf = 20 km of line 1 Line1 Line2 Line3 Line4 Line Fault Location [km] The proposed method is able to locate the faults by using single observa6on point (à no need for communica6on links) and limited 6me reversal window therefor it can be used as a backup protec6on to iden>fy the faulted line. 30 Fault Current Energy [Normalized] p2g fault at xf = 160 km of line 5, Rf=10 Ω Line1 Line2 Line3 Line4 Line Fault Location [km]

31 Key achievements 12 Sensi>vity of the fault loca>on as a func>on of the 6me- reversed window length Fault Current Energy [Normalized] p2g fault at xf = 20 km of line 2, Rf=10 Ω Δ T= 3 ms Δ T= 4 ms Δ T= 5 ms Δ T= 7 ms Δ T= 180 ms Fault Location [km] Related publica6on: R.Razzaghi, M. Paolone, F. Rachidi, J. Descloux, B. Raison and N. Re>ère Fault Loca>on in Mul>- Terminal HVDC Networks Based on Electromagne>c Time Reversal with Limited Time Reversal Window, Proc. of the 18th Power Systems Comput. Conf., Aug.18-22, 2014, Wroclaw, Poland. 31

32 Next steps The EMTR-based fault location method has been successfully validated for the multi-terminal HVDC networks in the offline simulation case studies. In the next step, the proposed method is going to be integrated with the developed real-time circuit solver running in the FPGA to build a smart relay for the MTDC networks. The final goal, is to develop a smart relay which is able to detect the DC faults and find the fault location. The developed relay will include the following tasks: (i) read the recorded fault-orignated transient signals in a single-observation point, (ii) perform the time-reversal process on the recorded signal, (iii) identify the faulted line and find the fault location. 32

33 Project "High-current DC testing" Milestone/Deliverable Concept and build-up of prototype for HVDC CB test facility HIL Test Source for CB Status: on-going Project objectives (and status, e.g. "achieved"): on-going Project activities (Jan-Dec 2014): Built up, programming and testing of a prototype of a single module (5.5kV/ 1.4kA) with ohmic load. (Will be finalised Q1/15). Project results: Prototype system Partners Academic: ETH-HPE, ETH-EEH 33

34 UnACuSo Principle of Opera>on of UnACuSo with Current Genera>on by the 3 Level System and Voltage Addi>on by the M 3 TC Output Current I out is generated by 3 Level Converter System Output Voltage V out is generated by Load M 3 TC is limiting V C to voltages between 0 V and 550 V 34 Schema>c Overview of UnACuSo

35 Key achievements Web- based Interface for controlling and monitoring UnACuSo Modular Marx- type Mul>- Level Converter (M 3 TC) 3 Level Converter Measurement result of the 3- Level converter system with an sinusoidal output current of 60 A at 100 Hz. 35

36 Next steps Connection of 3 Level Converter and Modular Multi-Level Converter (M 3 TC) Increasing the Output Voltage and Current to 5.5 kv and 1.4 ka Controller Optimisation for Operation with an DC Arc as Load 36

37 Contact: Patrick Favre-Perrod