Ukujima Photovoltaic Park 400...

PHOTOVOLTDEVELOPMENT PARTNERS

29 Juli 2014

Ukujima Photovoltaic Park 400 MWStable Integration of a 400MW Photovoltaic Farm int o the Japanese Power

System – Challenges and Chances


29 Juli 2014

Characteristics of the Project

2

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

Network Operator at PCC Kyushu Power & El.

Length to PCC 65.5 km

Voltage at PCC 220 kV

約５００m

漁業権境界

Ukujima S/S

400 MW

Ainoura S/S220 kV

65.5 km


29 Juli 2014

3

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!

Challenges: Project Internal DesignGeneral Considerations


29 Juli 2014

4

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 1.600 mm² Al

General Structure of the internal MV Network

Challenges: Project Internal DesignGreen-Field Network Planning

AB C

33 kV

D


29 Juli 2014

Challenges: Project Internal DesignPower Transmission Technology to Ainoura

HVDC

LCC- / CSC-Technology *1

- Use Since early 1950

- Requires connection of two active power networks at both sides of the link

VSC-Technology *2

- Use since 1999

- Contrary to LCC, can be applied for linking isolate networks, like remote islands

HVAC

- Use of AC technology for long distances on- and offshore is well approved and experienced

Not applicablefor Ukujiima!

Applicablefor Ukujiima!

Applicablefor Ukujiima!

*1 Line Commutated Current-Sorced Converter*2 Voltage Source Commutated

For both technologies practical

experiences are available

vs.


29 Juli 2014

Challenges: Project Internal DesignInt’l HV Power Transmission Experiences

Other worlwide appli-

cations – besides

Germany / Europe –

are available for both

technologies as well!

VSC -HVDC HVAC

The power to be

transmitted

The length of

connection

Conclusion

for the

UMSP project

400 MW

65 km

Both Technologies

- HVAC and HVDC –

are applicable!


29 Juli 2014

Advantages Disadvantages

HVDC • Independent control of Active

and Reactive Power

• 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

• More References

• Expected influences to the existing

transmission system 220kV

Separate System Studies are necessary

Challenges: Project Internal DesignOptimal HV Power Transmission Technology


29 Juli 2014

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

II. Electromagn. Transient Analysis

•Voltage Drops, Surge Resonances and

Harmonics during switching processes

•Zero-miss currents during normal and

disturbed network conditions

•Effects of the Cable Discharge to the existing equipment (e. g. breakers)

•Lower Harmonic Resonances during a Fault Current

Challenges: Project Internal DesignNeed and Content of System Studies

0

50

100

150

200

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

Imp

ed

an

ce [

Oh

m]

Frequency [Hz]

Z=f(f) without UMSP

Z=f(f) with UMSP Displacement of the Resonancedue to the long HVAC cable


29 Juli 2014

Challenges: Project Internal DesignPowerful System Analysis Software

• Load Flow analysis and Short-Circuit Analysis ( IEC 60909, ANSI C37, IEC 61363, complete method, multiple faults, DC Short-Circuit calculation according to IEC 61660 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 61400-21), Flicker Meter (IEC 61000-4-15)

– 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

PowerFactory – DIgSILENT, Germany


29 Juli 2014

Output

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 long-distance submarine cables (e. g. harmonic filters, surge arresters)

• Definitions for the setting of the Protection Devices

Challenges: Project Internal DesignOutcome of the System Studies

System

Study

Contribution to a Stable Operation of the Transmission System

InputCons-trution

Challenges Chances


29 Juli 2014

The Operator of the Transmission System (TSO) is responsible for the keep of it’s Stability!

Chances: Stability of Transmission SystemsStability Criteria

Power System Stability

Frequency Stability Voltage Stability Rotor Angle Stability *

Stability of the ActicePower Balance

Stability of the ReacticePower Balance

Small SignalStability

Large Signal(Transient Stability)

Generation

SystemFrequency

Demand

TSO

Umin

Pmax

Balanced ReactivePower Area

Unbalanced ReactivePower Area

Safe Operation Area

CriticalOperationArea

ImpossibleOperation Area

U

P** * Not in Scope** Source: EirGrid


29 Juli 2014

The Main International Requirements to Generating Units – including Renewables – are:

Chances: Stability of Transmission SystemsStability Requirements to Generating Units

Criterion Description of the Requirement Stability Type

JEAC 9701

Frequency range Normal operation 47.5 Hz ≤ fr50Hz ≤ 51.5 Hz or 57.0 Hz ≤ fr60Hz ≤ 61.8 Hz (Europe 48.5 Hz ≤ fr50Hz ≤ 50.5 Hz)

Frequency�

Voltage range Normal operation between 80% ≤ Ur ≤ 120 % (Europe 80% ≤ Ur ≤ 120 %)

Voltage�

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

Detailed Requirements to Renewables according to JEAC 9701-2012:


• No specific requirements regarding the control of the active power due to frequency deviations

• Power Factor between0.9 lag and 0.95 lead (systems point of view)

• No specific requirements regarding theinfeed of a reactive current during

• Not disconnection during a voltage drop down to 20% Ur over 0.3 sec

• Reversion to 80% of Ur within 0.1 s afterclearence of the external network failure

• Achievement of the origin voltage after 1.5 sec

-200

-150

-100

-50

0

50

100

150

200

-400 -350 -300 -250 -200 -150 -100 -50 0 50 100

Q [M

var]

P [MW]

PMax

Lagging 0.85

0.9 lag

0.95 lead

+Q

-Q

+P-P

Active PowerControl

Reactive PowerControl

Fault-Ride-Through

0

10

20

30

40

50

60

70

80

90

100

110

-0.10 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50

Vo

lta

ge

Le

ve

l [p

. u

.]

Time [s]

After March 2017

Before March 2017


29 Juli 2014

Ability for Stability Support by the INVERTERS of the UMSP in Comparison to JEAC 9701


Criterion According to JEAC 9701-2012 Additional Abil ity

• Full Compliance to JEAC Normal Operation in the range 57.0 Hz ≤ fr60Hz ≤ 61.8 Hz

• AP Reduction starting froma Setpoint (e. g. 50.2Hz);• The Gradient of the Power Reduction in MW/Hz must beDefined by the TSO

• Full Compliance to JEAC

• Full Compliance to JEAC • Injection of a Reactive Current during the external network fault

• Additional support for theVoltage at the PCC

Active Power(AP) Control

Reactive Power Control

Fault-Ride-Through

nf

f∆

refP

P∆

n

i

f

f∆−

Active Power Setpoint

Droop

-150

-100

-50

0

50

100

150

200

-400 -350 -300 -250 -200 -150 -100 -50 0 50 100

Q [

Mva

r]

P [MW]

0.9 lag

PMax

0.95 lead

0.85 lag

Reverse Power FlowNon-Reverse Power Flow


29 Juli 2014

Summarize: How UMSP is able to meet stability requirements of JEAC?

Chances: Stability of Transmission SystemsCapabilities of the Renewables Assets

Criterion Description Inverter - Cability according toJEAC 9701 Add. Ability

Active Power ControlNormal operation 57.0 Hz ≤ fr60Hz ≤ 61.8 Hz

AP Variation during Frequency deviations

Reactive Power ControlNormal operation between 80% ≤ Ur ≤ 120 %

0.9 lag ≤ cos φ ≤ 0.9 lead

Fault-Ride-ThroughNot 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

Please don’t hesitate to ask any questions at any time

Contact:

Photovolt Development Partners GmbHKurfuerstendamm 136, D-10711 Berlin

Joerg Zillmer Peter GerstmannPrincipal Consultant Managing DirectorPhone: +49 173 6095034 Phone: +49 30 375926711email: [email protected] email: [email protected]


29 Juli 2014

Chances: Stability of Transmission SystemsCapabilities of Renewables Assets

1

23

f / Hz

P / kVA

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