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Power Electronic
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| Slide 1
| Slide 2
Introduction
| Slide 3
Introduction
Power Electronics:
Application of solid-state electronics for efficient control andconversion of electrical power
Often employed whenever there is a need to modify a form ofelectrical energy (either changing its voltage, current or frequency)
Potential to make a huge contribution to the low carbon economy
Technology where Malaysia has a high growth and high value,making a significant contribution to exports and the wealth of thenation, as well as providing high-quality employment.
| Slide 4
Technical
| Slide 5
Technical: Overview Wind Turbine
Technical: Overview Wind Turbine
| Slide 6
Use a Squirrel Cage Induction Generator Directly connected to grid (through a soft starter) Needs capacitor banks for reactive power
compensation
Fixed Speed Technology
| Slide 7
Doubly Fed Technology
Doubly fed asynchronous generator Stator directly connected to the grid, power converter in
the rotor circuit Allows for variable speed, hence better caption of
energy from wind
Technical: Overview Wind Turbine
| Slide 8
Full Scale Converter Technology
Many type of generators can be used, e.g. (PM) Synchronous generator, Asynchronous generator
With and without gearbox depending on generator design
Full power converter between the generator and the grid
Technical: Overview Wind Turbine
| Slide 9
Technical: Overview Wind Turbine
Problem Statement
The operation of an ac power transmission line is generally constrained by limitations one or more network parameters (e.g line impedance) and operating variables (e.g voltage and current)
As a result, the power line is unable to transfer power among generation stations. Therefore, other parallel transmission lines that have an adequate capability of carrying additional amount of power may not be able supply the power demand.
| Slide 10
Technical: Overview Wind Turbine
Large loads consume huge amounts of power and cause an excessive voltage drop which at the extreme becomes a complete collapse of the voltage.
In the other direction load shedding of a capacitive line or heavily compensated line can cause over voltages.
Switching of loads or power factor capacitors causes steps in voltage (inrush current factor 5…9 of rated power)
Rapidly varying loads or pulsing (choppering) cause voltage flickers.
Industrial grids (plants) with many different participants (loads) have network specific harmonics
Problem Concern
| Slide 11
Technical: Overview FACTS
FACTS Definition
Flexible Alternating Current Transmission System (FACTS) is newemerging technology and its principal role is to enhance controllabilityand power transfer capability in ac systems.
FACTS is defined by the IEEE as a power electronic based system andother static equipment that provide control of one or more ACtransmission system parameters to enhance controllability andincrease power transfer capability.
FACTS controllers are capable of controlling the interrelated lineparameters and other operating variables that govern the operation oftransmission lines series impedance, shunt impedance, current,voltage, phase angle and damping oscillation at various frequencybelow rated frequency.
| Slide 12
Technical: Overview FACTS
FACTS
Shunt Compensation
TSC
TCR
SVC
STATCOM
Series Compensation
TSSC
TCSC
FCSC
SSVC
SSTATCOM
Phase-Angle Compensation
UPFC
| Slide 13
Technical: Overview FACTS
FACTS Comparison
| Slide 14
Technical: STATCOM Solution
| Slide 15
Technical: STATCOM Solution
Static synchronous compensators (STATCOMs) are part of the flexiblealternating current transmission systems (FACTS) device family.
Their primary purpose is to supply a fast-acting, precise, and adjustableamount of reactive power to the ac power system to which they areconnected.
STATCOMs achieve this by adjusting the magnitude and polarity(phase) of the reactive component of the current flowing through theirac side.
This enables STATCOMs to control the amount and direction of flow ofthe reactive power exchanged with the ac power system.
| Slide 16
Technical: STATCOM Solution
STATCOMs can be used for voltage compensation at the receiver end of ac transmission lines, thus replacing banks of shunt capacitors.
When used for this purpose, STATCOMs offer a number of advantages over banks of shunt capacitors, such as much tighter control of the voltage compensation at the receiver end of the ac transmission line and increased line stability during load variations.
STATCOMs are also commonly used for dynamic power factor correction (i.e., dynamic reactive power compensation) in industrial plants operating with large random peaks of reactive power demand.
STATCOMs increase the power factor of the plant, minimize the voltage fluctuations at the plant input (which prevents damage to the equipment), and reduce the plant’s operating costs.
| Slide 17
Technical: STATCOM Solution
| Slide 18
Technical: STATCOM Principle
| Slide 19
Technical: STATCOM Principle The STATCOM current amplitude is defined by the voltageacross the transformer. The maximum voltage supporting current is defined by the maximum STATCOM converter output voltage. The maximum voltage suppressing current is defined by the maximum converter current
Each voltage drop/swell of Upoc causes an inherent, immediate reactivecurrent over the transformer which works against the disturbance. Reactive power injection after STATCOM voltage increase, Uconv will starting within <10ms.
Ugrid=UpocUcompensator=Uconv
| Slide 20
Technical: STATCOM Principle
| Slide 21
Technical: STATCOM Location
Where to install the STATCOM?
Key factors to be considered for location of STATCOM:Access (Offshore vs Onshore)Maintenance (Offshore vs Onshore)Losses (Power System Study)Capital (Project Stage)Operating Costs (Operation Stage)
| Slide 22
Technical: STATCOM Location
| Slide 23
Technical: STATCOM Location1) Wind Turbine Level
| Slide 24
Technical: STATCOM Location2) Wind Farm Level (Collector Point)
| Slide 25
Technical: STATCOM Location3) Wind Farm Level
| Slide 26
Technical: STATCOM Location4) Wind Farm Level *
* Offshore Application
| Slide 27
Technical: STATCOM Location
| Slide 28
Technical: STATCOM Location
| Slide 29
Technical: STATCOM Location
| Slide 30
Technical: STATCOM Application
Reactive power compensation solution should be selecteddepending on the application.
If static response and no continuously adjustable response is required, switched passive components are sufficient
Passive components: Transient when switched on or off Slow response time
If dynamic response and continuously adjustable response is required, STATCOM is more suitable
STATCOM components:Requires filtering in some casesVery fast response time
| Slide 31
Technical: STATCOM ApplicationSwitched Capacitors / Reactors
| Slide 32
Technical: STATCOM ApplicationSTATCOM
| Slide 33
Technical: STATCOM Application
The continuous increase of installed wind turbine seen during recent years has forced the transmission system operators (TSO) to tighten their grid connection rules which also known as Grid Code.
A grid code is a technical specification which defines the parameters a facility connected to a public electric network has to meet to ensure safe, secure and economic proper functioning of the electric system.
The Grid Code is very important in order to limit the effects of wind turbine farm on network quality and stability.
1) Grid Code Compliant
| Slide 34
Technical: STATCOM Application1) Grid Code Compliant
| Slide 35
Technical: STATCOM Application1) Grid Code Compliant
| Slide 36
Technical: STATCOM Application1) Grid Code Compliant
| Slide 37
Technical: STATCOM Application
Key issues are steady state and dynamic reactive power capability, continuously acting voltage control and fault ride through behavior.
STATCOM (Static Synchronous Compensator) technology which adds the missing functionality to wind turbine in order to become Grid Code compliant.
1) Grid Code Compliant
| Slide 38
Technical: STATCOM Application
Resonance issues arise in wind power plants because wind power plants contain both inductive source characteristics and capacitive elements.
Feeder line and cable capacitance and the substation reactive compensation equipment can create significant parallel resonance interaction with the main transformer.
2) Resonant Damping
| Slide 39
Technical: STATCOM Application2) Resonant Damping
| Slide 40
Technical: STATCOM Application3) Active Harmonic Filtering
| Slide 41
Technical: STATCOM Application4) Reactive Power (Q) demand during starting
| Slide 42
Technical: STATCOM Application
| Slide 43
Conclusion
| Slide 44
Conclusion
STATCOM must be installed in order for wind turbine farm before can get connected to national grid due to stringent Grid Code applied.
STATCOM have vital roles to enable the renewable energy generation combination on national grid. Without STATCOM, wind turbine can only work in isolated network.
STATCOM offer optimisation of power output, reduce harmonic and ensure continuous stability to power system regardless the compensation demand whether static response or dynamic response.
The effectiveness of STATCOM can be further improved by introducing the energy storage devices such as BESS or DynaPeaQ system.
| Slide 45
Question?
| Slide 46