Ukujima Photovoltaic Park 400 MW Stable Integration of a 400MW Photovoltaic Farm into the Japanese Power System Challenges and Chances

Transcription

1 Ukujima Photovoltaic Park 400 MW Stable Integration of a 400MW Photovoltaic Farm into the Japanese Power System Challenges and Chances 29 Juli 2014 Page 1

2 Characteristics of the Project Parameter Detail Generation Site Ukujima Island Source of Energy Photovoltaic Installed Power 430 MW Voltage at Generation Site 0.4 / 33 kv Point of Common Coupling Ainoura Substation Ainoura S/S 220 kv Network Operator at PCC Kyushu Power & El. Length to PCC Voltage at PCC 65.5 km 220 kv 400 MW 65.5 km Ukujima S/S 約 500m 漁業権境界29 Juli 2014 Page 2

3 Challenges: Project Internal Design General Considerations The installed capacity of 400MW is identically to kinds of conventional Power Plants The project s Character of a Power Plant and therefore the meaning for the existing Japanese Transmission System requires the consideration of appropriate technical solutions concerning The use of applications according to the State of the Art The fulfillement of the criteria for the reliability of power supply The knowledge of specifics for the Japanese Transmission system (e. g. JEAC) The application of international experiences for the grid connection of Renewables The electrical phenomena caused by the long submarine cable connection Two Issues are the main Challenge concerning the Planning Process: - A technical-economical Green-Field Structure for the Network at Ukujima - The Identification of the optimal HV power transmission technology! 29 Juli 2014 Page 3

4 Challenges: Project Internal Design Green-Field Network Planning Baseline Design PV Farm 400MW Internal PV-DC network 10Tkm Invertertstations 217 pcs. 434 Inverter 1000kVA each Network 33kV 150km - Radial MV network structure - max 18 Stations per MV-String - max 630 A per String - only Load-break switches Substation 220kV 2 x 250 MVA Submarine Cable 220kV 65km cross section mm² Al General Structure of the internal MV Network 33 kv A B C D 29 Juli 2014 Page 4

5 Challenges: Project Internal Design Power Transmission Technology to Ainoura HVDC vs. HVAC LCC- / CSC-Technology *1 - Use Since early 1950 Not applicable for Ukujiima! - Requires connection of two active power networks at both sides of the link Applicable for Ukujiima! - Use of AC technology for long distances on- and offshore is well approved and experienced VSC-Technology *2 - Use since 1999 Applicable for Ukujiima! - Contrary to LCC, can be applied for linking isolate networks, like remote islands For both technologies practical experiences are available *1 Line Commutated Current-Sorced Converter *2 Voltage Source Commutated 29 Juli 2014 Page 5

6 Challenges: Project Internal Design Int l HV Power Transmission Experiences VSC - HVDC HVAC Other worlwide applications besides Germany / Europe are available for both technologies as well! Conclusion for the UMSP project The power to be transmitted The length of connection 400 MW 65 km Both Technologies - HVAC and HVDC are applicable! 29 Juli 2014 Page 6

7 Challenges: Project Internal Design Optimal HV Power Transmission Technology Advantages HVDC Independent control of Active and Reactive Power Disadvantages More expansive than HVAC Cost Break-even >70km; lower losses will not compensate higher investment costs Space problems for the placement of the landside converter station Extreme long lead time HVAC Most economical solution considering CAPEX + OPEX Expected influences to the existing transmission system 220kV More References Separate System Studies are necessary 29 Juli 2014 Page 7

8 Challenges: Project Internal Design Need and Content of System Studies The Main System Study Issues due to the influence of the existing transmission system by a long distance HVAC cable are: I. Power Quality Analysis Impedance-Frequency-Curve and Harmonics 200 Impedance [Ohm] 150 Z=f(f) with UMSP Displacement of the Resonance due to the long HVAC cable Z=f(f) without UMSP II. Electromagn. Transient Analysis Voltage Drops, Surge Resonances and Harmonics during switching processes Zero-miss currents during normal and disturbed network conditions Frequency [Hz] Effects of the Cable Discharge to the existing equipment (e. g. breakers) Lower Harmonic Resonances during a Fault Current Juli 2014 Page 8

9 Challenges: Project Internal Design Powerful System Analysis Software PowerFactory DIgSILENT, Germany Load Flow analysis and Short-Circuit Analysis (IEC 60909, ANSI C37, IEC 61363, complete method, multiple faults, DC Short-Circuit calculation according to IEC and ANSI/IEEE 946) Optimal Power Flow (OPF): Reactive power optimization and economic dispatch Protection Functions: Time-Overcurrent Protection and Distance Protection; comprehensive relay library with relay models suitable for steady-state, RMS and EMT calculations Voltage stability analysis: PQ and QV curves; P-, Q-, I- and V-measurement models, consideration of load flow constraints, verification of system observability Cable Sizing: Automatic cable sizing and cable reinforcement optimization Basic MV/LV Network Analysis: Feeder Analysis Tool, Radial Feeder Tool, Backbone Calculation Power Quality and Harmonic Analysis Harmonic Load Flow and Filter Analysis: Various harmonic distortion indices, Multiple harmonic injections Flicker Analysis: Flicker Assessment (IEC ), Flicker Meter (IEC ) Impedance-Frequency-Curve: Balanced and unbalanced network model Stability Analysis Functions (RMS): balanced/unbalanced, multi-phase AC networks, DC networks, simulation of any kind of faults or events + Electromagnetic Transients (EMT): FACTS, HVDC interconnections, power electronic devices 29 Juli 2014 Page 9

10 Challenges: Project Internal Design Outcome of the System Studies The Main Outcome of the System Studies is: Definition of measures for a secure and stable operation under undisturbed conditions Fulfilment of the Grid Code requirements acc. to JEAC 9701 Definition of Countermeasures for the specific electrical phenomena due to longdistance submarine cables (e. g. harmonic filters, surge arresters) Definitions for the setting of the Protection Devices Challenges Chances Input System Study Output Constrution Contribution to a Stable Operation of the Transmission System 29 Juli 2014 Page 10

11 Chances: Stability of Transmission Systems Stability Criteria The Operator of the Transmission System (TSO) is responsible for the keep of it s Stability! Power System Stability Frequency Stability Voltage Stability Rotor Angle Stability * Stability of the Actice Power Balance Stability of the Reactice Power Balance Small Signal Stability Large Signal (Transient Stability) Generation U Balanced Reactive Power Area Unbalanced Reactive Power Area TSO System Frequency Demand U min Safe Operation Area CriticalOperation Area Impossible Operation Area ** P max P * Not in Scope ** Source: EirGrid 29 Juli 2014 Page 11

12 Chances: Stability of Transmission Systems Stability Requirements to Generating Units The Main International Requirements to Generating Units including Renewables are: Criterion Description of the Requirement Stability Type Frequency range Normal operation 47.5 Hz f r50hz 51.5 Hz or 57.0 Hz f r60hz 61.8 Hz (Europe 48.5 Hz f r50hz 50.5 Hz) Voltage range Normal operation between 80% U r 120 % (Europe 80% U r 120 %) Frequency Voltage JEAC 9701 Active Power Control Active Power Control within a given Frequency Range Frequency --- Reactive Power Control Possibility to meet a given P-Q-diagram independently to voltage changes (P-Q-diagram in a voltage band) Voltage Fault Ride- Through Stable connection during network faults within a give time-frame; (not in JEAC: injection of a reactive current) Voltage Information exchange Online transfer for the value of active power and possibility for its reduction by the grid operator Frequency Control system Voltage, reactive power or power factor control Voltage 29 Juli 2014 Page 12

13 Chances: Stability of Transmission Systems Stability Requirements to Generating Units Detailed Requirements to Renewables according to JEAC : Active Power Control No specific requirements regarding the control of the active power due to frequency deviations Reactive Power Control Power Factor between 0.9 lag and 0.95 lead (systems point of view) No specific requirements regarding the infeed of a reactive current during 0.9 lag 200 +Q P Max P [MW -P +P lead -Q Q [Mvar] Lagging 0.85 Fault-Ride-Through Not disconnection during a voltage drop down to 20% U r over 0.3 sec Reversion to 80% of U r within 0.1 s after clearence of the external network failure Voltage Level [p. u.] After March 2017 Before March 2017 Achievement of the origin voltage after 1.5 sec Time [s] 29 Juli 2014 Page 13

14 Chances: Stability of Transmission Systems Stability Requirements to Generating Units Ability for Stability Support by the INVERTERS of the UMSP in Comparison to JEAC 9701 Criterion According to JEAC Additional Ability Active Power (AP) Control Reactive Power Control Full Compliance to JEAC Normal Operation in the range 57.0 Hz f r60hz 61.8 Hz Full Compliance to JEAC P Max Reverse Power Flow 0.9 lag P [MW] lead Q [Mvar] 200 Non-Reverse Power Flow lag AP Reduction starting from a Setpoint (e. g. 50.2Hz); The Gradient of the Power Reduction in MW/Hz must be Defined by the TSO P P ref Active Power Setpoint f f n i Droop f f n Fault-Ride- Through -150 Full Compliance to JEAC Injection of a Reactive Current during the external network fault Additional support for the Voltage at the PCC 29 Juli 2014 Page 14

15 Chances: Stability of Transmission Systems Capabilities of the Renewables Assets Summarize: How UMSP is able to meet stability requirements of JEAC? Criterion Description Inverter - Cability according to JEAC 9701 Add. Ability Active Power Control Normal operation 57.0 Hz f r60hz 61.8 Hz AP Variation during Frequency deviations Reactive Power Control Fault-Ride-Through Normal operation between 80% U r 120 % 0.9 lag cosφ 0.9 lead Not Disconnection; Voltage Recovery Reactive Current injection during FRT UMSP is able to meet the Stability requirements by JEAC AND to provide additional services for the keep of the stability! 29 Juli 2014 Page 15

16 Please don t hesitate to ask any questions at any time Contact: Photovolt Development Partners GmbH Kurfuerstendamm 136, D Berlin Joerg Zillmer Peter Gerstmann Principal Consultant Managing Director Phone: Phone: zillmer@pvdp.eu gerstmann@pvpd.eu 29 Juli 2014 Page 16

17 Chances: Stability of Transmission Systems Capabilities of Renewables Assets P / kva f / Hz 29 Juli 2014 Page 17