Power Plant Control for Utility Scale GmbH Ernst Augustin ... · PDF filePower Plant Control for Utility ... power plant supervision skycontrol Power plant controller forgrid stability

skytron® energy GmbH 08 / 2011 Page 1

Power Plant Controlfor Utility‐Scale Photovoltaic Installations

skytron® energy GmbHErnst‐Augustin‐Str. 12D – 12489 BerlinGermany, Berlin

www.skytron‐energy.com

skycontrol


1. Monitoring, Control and Supervision

2. Control... of what? And Why?

3. Different Control Approaches

4. skytron’s Power Plant Controller


Monitoring, Control and Supervision

• Plant operation always “in view”• Reduced downtimes• Availability tracing• Enhanced efficiency and yield• Secured investment (ROI)

• Monitoring• Control• Supervision• Operation & Maintenance (O & M)• Asset Management

Your Benefit

Our Job

POWER CONVERSION CHAIN

… covering the entire power plant!


SupervisoryLevel

Plant ControlLevel

Data AcquisitionLevel

Field Level

PVGuard®Remote SCADA platform for multi‐vendor multi‐site

power plant supervision

skycontrolPower plant controller for grid stability

Data Acquisition Level

skylog®High resolution real‐time data logging and

preprocessing


ArrayGuard®Intelligent combiner boxes

skyCONNiField sensorics

StringGuard®String current monitoring

EnergyGuardEnergy meter monitoring

Power Plant Architecture

Monitoring, Control and Supervision


Electricalfield quantities

Ambient field quantities

Plant fault / status information

Measurement & Data Acquisition


Remote Plant Supervision







Utility‐Scale PV Installations

• Plant operation always “in view”• Reduced downtimes• Availability tracing• Enhanced efficiency and yield• Secured investment (ROI)

• Monitoring• Control• Supervision• Operation & Maintenance (O & M)• Asset Management

Your Benefit

Our Job

POWER CONVERSION CHAIN

… covering the entire power plant!


Why is Control Required?

Source: Siemens AG

TODAY:

• Distributed bulk power systems feed into an electricity grid which originally was designed forcentralized, top‐down electricity distribution and supply.

• At low‐voltage andmedium‐voltage levels

• ‐Wind power plants‐ Photovoltaic power plants‐ CSP power plants‐ Biogas power plants‐ Tidal wave plant‐ Geothermal plants


The Effect Upon the Electricity GridDa

ily m

eanload

/ gen

eration [GW]

Load Solar Wind Water Biomass Geothermal Residual load

Time


• Fluctuating load profiles (day, night)

• Fluctuating energy injection by “Renewables” due to variable weather conditions

• Irregular energy injection and energy extraction in sub‐grids

• Limited energy transport capacities of “historic” transmission and distribution grids

• Limited capabilities of conventional power plants to balance out those fluctuations

• Grid faults ‐ sudden load shedding and short circuits

Grid Security Grid Stability

Today’s Electricity Grid Characteristics

Grid security management measures

‐ On‐demand reduction of energy injectionin the event of grid overload

Decentralized grid stability measures

‐ Voltage support

‐ Injection of reactive power (cos ø)

‐ Frequency stability monitoring

‐ Fault ride through

‐ Provision of short circuit current (LVFRT)


• Improved grid stability thanks todecentralized grid support:

‐ Voltage support‐ Injection of reactive power‐ Frequency monitoring

• The controllable power plant improvesthe grid quality

‐ either instantly, according to actualdemand of power supply company

‐ or according to an agreed specification

Grid Stability

overexcited

unde

rexcite

d

0.95

0.95







Power Plant Control: Two Approaches

Controller PlantPsetpointQsetpoint

+ -

Pactual

Qactual

Inverter Level Plant Level

• Typically open‐loop control

• Feedback of actual value P, Q ?

• Actual value pick‐up at injection point: LV

• Integration in SCADA system possible?

• Closed‐loop control

• Feedback of actual value P, Q: Yes

• Actual value pick‐up at injection point: LV, MV, HV

• Integration in SCADA system possible? Yes


skytron’s Approach: Power Plant Controller

LOSSES !


Monitoring, Supervision … … and Control

SYSTEM INTEGRATION







skytron’s Power Plant Controller: skycontrol

skycontrol

Software

Hardware / Control Cubicle

System / Control Principle


• Genuine closed‐loop control

• Feedback of actual values at grid injectionpoint at medium or high voltage level

• Grid parameters:‐ effective power P‐ reactive power Q‐ grid frequency f‐ grid voltage V

• Effective power control(NSM – Network Security Management)

• Reactive power compensation

• Reactive power injection(grid support function)

Characteristics and Control Parameters


skycontrol: The Control Principle

Dynamic grid support‐ short‐circuit current‐ Fault Ride Through

Static grid support‐ effective power control‐ reactive power control

Feedback‐ Setpoint/actual P, Q‐ Generation prognosis

Grid control system

Network Security ManagementEffective power control100% / 60% / 30% / 0%

Communicationand

control unit

Inverters

Generator

High and mediumvoltage switchgear

Medium voltage level(e.g.: 20 kV)

High voltage level(e.g.: 110 kV


skycontrol: The Hardware

• Different‐size cubicles, depending on required‐ control features‐ housing‐ interfaces

• Customized to suit‐ interfaces specified by power supply company‐mounting space available‐ layout and configuration of PV power plant‐ required functional scope

• skycontrol‐ is NOT a standard power plant controller‐ is a plant control system – adjusted to customer


Network Security management (NSM)

Effective Power Control

• Discrete switching signals (0%, 30%, 60%, 100%)• Analog signals (4 to 20 mA, 0 to 10 V)• Digital interfaces (MODBUS, BACnet)

Reactive Power Control

• Discrete switching signals (0%, 30%, 60%, 100%)• Analoge signals (4 to 20 mA, 0 to 10 V)• Digital interfaces (MODBUS, BACnet)• Characteristic working curve of grid frequency→ P(f)

• Agreed value, fixed• Discrete switching signals (cos φ: ‐0.9, ‐0.95, 1, +0.95, +0.9)• Analog signals (4 to 20 mA, 0 to 10 V)• Digital interfaces (MODBUS, IEC 60870)• Characteristic working curve of effective power → Q(P)• Characteristic working curve of reactive power → Q(V)

Integration of System Protection Signals

• Grid injection enable• Emergency OFF / Fast trip• Inverter control in the event of MV / HV switch‐off

Functions Setpoint inputs:

skycontrol: The Functional Scope


SupervisoryLevel

Plant ControlLevel

Data AcquisitionLevel

Field Level

PVGuard®Remote SCADA platform for multi‐vendor multi‐site

power plant supervision

skycontrolPower plant controller for grid stability


skylog®High resolution real‐time data logging and

preprocessing


ArrayGuard®Intelligent combiner boxes

skyCONNiField sensorics

StringGuard®String current monitoring

EnergyGuardEnergy meter monitoring

Full System Integration

Instrumentation and Control: Fully Integrated


• TODAY, more than 1.8 GWp of total capacity installed all over the world, rely on skytron’s monitoring and control system for utility‐scale photovoltaic power plants

• More than 30 power plants are supervised and managed from our Berlin control room

Reference Projects (Excerpt)

Our Partners (Excerpt)


Ernst‐Augustin‐Str. 12D – 12489 Berlin, Germany

www.skytron‐energy.com

skytron® energy GmbH

+49 (0)30 688 31 59 – 0info@skytron‐energy.com

Documents

Power Plant Control for Utility Scale GmbH Ernst Augustin ... · PDF filePower Plant Control for Utility ... power plant supervision skycontrol Power plant controller forgrid stability