[public] abb operational experiences of statcoms for wind parks

8/17/2019 [Public] ABB Operational Experiences of STATCOMs for Wind Parks

http://slidepdf.com/reader/full/public-abb-operational-experiences-of-statcoms-for-wind-parks 1/12

/12

Operational Experiences of STATCOMs for Wind Parks

Beat Ronner, ABB Switzerland Ltd,[email protected]

Philippe Maibach, ABB Switzerland Ltd,[email protected]

Tobias Thurnherr, ABB Switzerland Ltd,[email protected]

1 IntroductionFollowing the increasing importance of renewable power generation in certain countries orregions, grid operators are forced to introduce stringent Grid Code requirements which alsoapply for wind parks. The requirements include fault ride through, dynamic reactive power

generation and steady state voltage control.Certain wind turbine types, however, are not able to inherently fulfil certain grid codes. In thatcase, additional equipment is needed to get the connection permission. A lot of work has been done until present to examine the static and dynamic performance ofSTATCOMs with respect to voltage control and support during a fault. Besides that, thebehaviour of STATCOMs has been compared with other reactive power compensationsolutions, like capacitor banks, SVCs or synchronous compensators. ([9][12][13][14][15])This paper presents practical experiences from STATCOMs based on medium voltage IGCTtechnology, which has been successfully implemented for various industrial and utilityapplications for several years. After a brief overview of the chosen solution, the steady state aswell as the dynamic performance of the STATCOM are described and underlined withmeasurements from several realized STATCOM installations in different countries. Besides that,additional features of the STATCOM are presented.

2 System DescriptionBecause wind parks are growing in size, their behaviour during grid faults can no longer beneglected. They are required to principally behave like conventional power plants. This is one ofthe main reasons why transmission and distribution system operators (TSO, DSO) havedeveloped detailed grid codes in order to specify the behaviour of wind parks in their grids.Keywords in this context include frequency control, voltage control and fault ride-throughbehaviour.Frequency control is influenced by active power and is therefore a task of the wind turbinecontrol. Reactive power compensation equipment as described in this paper cannot influencethe system frequency. The voltage, contrarily, is influenced by the reactive power of the windpark. This can to some extent be achieved by the wind turbine control. However, some windturbines are not able to fulfil the grid code requirements with respect to static and dynamicreactive power control.The classic electrical wind turbine concept contains a fixed speed asynchronous generator.With this setup, the reactive power can not be controlled. Moreover, depending on the activepower output of the turbine, it absorbs more or less reactive power. For a certain point ofoperation, the power factor can be corrected to unity using passive elements (capacitors).The currently most common wind turbine concept is based on a doubly fed asynchronousmachine. With a converter feeding the rotor circuit, a variable speed characteristic can beachieved. Contrarily to turbines with a full power converter, the doubly fed does not require aconverter dimensioned for the full generator power. Theoretically, such turbines are able tocontrol their reactive power output. However, it depends on the converter design and on thecontrol system if they are able to fulfil requirements from grid codes.For turbines which do not inherently fulfil the applicable grid code in terms of reactive power, aSTATCOM can be added to make the wind park grid code compliant.



/12

Most grid codes require the wind park to remain transiently stable and connected to the grid andeven inject reactive power during a fault to as far as 0% of nominal voltage. Different studiesshow that a STATCOM can help the wind park ride through grid faults ([9],[15]). Simulationsresulted in the conclusion that the STATCOM supports the wind park during and especially aftera fault in such a way that the wind park voltage recovers faster. Compared to other reactive

power compensators, the required STATCOM power was shown to be considerably smaller tohave the same supporting effect.

A STATCOM is basically a voltage source with controllable amplitude connected to the grid viaan inductance. Figure 1 shows the principle, a simplified single-line diagram and two phasordiagrams. The STATCOM consists of a voltage source converter (VSC) with its DC link and atransformer (or reactor) with impedance XT connecting to the grid. The single-line diagram andthe phasor diagrams are a per-unit representation of the STATCOM. The VSC voltage phasorUComp has to be in phase with the grid voltage phasor UGrid in order to avoid active powerexchange between grid and STATCOM

1. As long as both UComp and UGrid have the same per-

unit value, no current will flow through the impedance XT. If the STATCOM converter voltagephasor UComp is larger than the grid voltage phasor, a current IGrid will flow through theimpedance XT. Since the impedance XT is mainly inductive, the phasor of this current is

perpendicular to the voltage drop across XT (phasor UT) and therefore also to the grid voltagephasor UGrid. The STATCOM injects reactive current into the grid. Comparably, if the STATCOMconverter voltage phasor UComp is smaller than the grid voltage phasor, the STATCOM absorbsreactive current from the grid. A STATCOM injecting reactive current behaves like an over-excited generator or a capacitor: It supports the grid voltage. A STATCOM absorbing reactivecurrent behaves like an under-excited generator or a reactor: It tends to decrease the gridvoltage.

Figure 1 - The STATCOM principle

1 In fact, the phasors are not completely in phase because the STATCOM losses have to be

compensated. However, the phase angle is very small and can therefore be neglected tounderstand the principle

UComp

XT

UGrid

IGrid

UTI Grid

XT

~

=

U Comp

UGrid

UT

IGrid

UComp

UT

IGrid

"capacitive"

over-excited

"inductive"

under-excited

UGrid

UT

Ugrid

Ucomp



/12

Figure 2 – Example of a connection of the STATCOM to the wind park MV bus

The STATCOM can provide reactive power following different control strategies:• Controlled reactive power output according to a reference from the wind park controller• Control of the power factor at e.g. the point of connection of the wind park• Operation according to a voltage/reactive power slope characteristic where the

STATCOM is able to accept a target voltage and a slope setting from the wind parkcontroller

In a wind park, the STATCOM is usually connected to the wind park MV bus, as shown inFigure 2. This applies for all cited installations.

Compared to other principles for reactive power compensation, the STATCOM includes severaladvantages as outlined in [1]:

• Possibility to inject constant reactive current down to very low voltage levels. This is thereason for the superior behaviour of a STATCOM right after a fault: It is able to supportthe grid with full reactive current independent of the grid voltage.

• Very fast response to voltage steps.• Since no switched passive components are used, there are no disturbing resonance

effects caused by e.g. capacitor switching.• Smooth and fast continuously acting reactive power source as often required by grid

codes.

3 STATCOM Modules – ABB Solution A comparison of actual wind park sizes and requirements from important grid codes showedthat the reactive power compensation equipment needs to be sized in the order of a few tens ofMvar. For this power range, medium voltage power electronic equipment is most cost effective.Therefore, power electronic building blocks based on IGCTs (Integrated Gate CommutatedThyristors) are used in modular voltage source converters, see [2]. This technology has beensuccessfully applied in various applications, like MV drives, frequency converters, wind turbineconverters, AC excitations, etc.The operational experiences shown hereafter are mostly gained from installations ratedapproximately 12 Mvar. This STATCOM size is adequate for a wind park with around 30MWnominal output power, if the turbines run at unity power factor and the grid code specifies thatthe wind park has to be able to run between PF=0.95 leading and 0.95 lagging (as for example

in Great Britain). In that case, the STATCOM reactive power has to be rated roughly one third ofthe total wind park active power.



/12

However, there are also examples from STATCOM units with an output power between 20 Mvarand 30 Mvar.

4 Verif ication Process of STATCOM PerformanceThe performance of a STATCOM is verified in several steps:

• Design calculations and studies• Software simulations• Tests on a dedicated hardware-in-the-loop simulator• Converter heat-run test in the factory at full rated current and voltage• Site acceptance tests

The results of design calculations and studies include the reactive power performance chart(see Figure 3), components specifications, e.g. transformer and grid filter, and calculation ofharmonic distortion caused by the STATCOM.Parallely to the assembly of the hardware, the control algorithms and site specific requirementsare implemented and studied. Afterwards, detailed measurements are done on the hardware-in-the-loop simulator. This development and test environment allows to study the real control

hardware and software of a STATCOM running on a scaled down power system. The scaledpower system model is either microprocessor based (dSPACE) or built with real electroniccomponents including the power electronics, transformers, a grid model and passivecomponents as far as relevant. The grid model is adapted to the real on-site short-circuit power.On this setup, the behaviour of the STATCOM during grid disturbances is studied andoptimised. As such, it is a very powerful tool to develop and optimise the control structure andparameter settings of a STATCOM. Furthermore, it can greatly support trouble shooting if in alater stage of a project problems should occur.Before delivering the STATCOM and after the standard routine tests, a heat-run test isperformed with nominal current and voltage. The purpose of this test is to run allsemiconductors for at least 10 times their thermal time constant. Additionally, this test provesthe integrity of the conductors and connections. The factory test can be witnessed by thecustomers.

The most interesting tests are performed on site after erection and commissioning of theSTATCOM. The following chapters are based on an example of an installation in the UK if nototherwise stated. The UK National Grid company issued comprehensive Guidance Notes forPower Park Developers [3], where a clear process for studies and tests to reach grid codecompliance is outlined. Tests performed with the STATCOM are based on these guidancenotes.

5 Steady State Reactive Power RequirementsFigure 3 shows an example of a STATCOM installation in the UK. In this diagram, the voltage isdepicted in a per-unit scale on the y-axis. On the x-axis, negative reactive power meansreactive power absorption from the grid (STATCOM in under-excited mode), positive reactivepower means reactive power injection into the grid (STATCOM in over-excited mode). The area

limited by the dash-dotted line represents the grid code requirement whereas the area limited bythe grey line represents the somewhat more demanding requirement given in a Bilateral Agreement. Although the basic requirements are given in the grid code, it is common in the UKto define additional site-specific requirements in a Bilateral Agreement. The area between thesolid blue lines represents the operating range of the STATCOM. The crosses represent theoperating points run during the acceptance tests on site: At almost nominal grid voltage, theSTATCOM was run at full injecting and full absorbing reactive power for at least one hour asspecified in the acceptance criteria given in [3]. These measurements were done to verify theagreed reactive power provided by the STATCOM. During this test, the grid voltage was keptstable by the tap-changer of the upstream transformer.



/12

1.001.00

0.85

0.95

1.05

1.15

-15 -10 -5 0 5 10 15

Reactive Power [Mv ar]

G r i d

V o l t a g e [ p . u . ]

STATCOM theoretical operation limits [MVA]

NGC Requirements [Mvar]

Grid Code Requirements [Mvar]

Measured inductive Vars (under-excited)

Measured capacitive Vars (over-excited)

Figure 3 - Steady state reactive power requirements, design and measurements

The operation area of the STATCOM is limited by the output current and voltage the STATCOMconverter is designed for. The maximum current is constant down to approximately 15% ofnominal grid voltage. Therefore, the maximum reactive power varies linearly with the gridvoltage. This current limit is reflected in the lines 1). The STATCOM converter output voltage islimited. Combined with the turns-ratio and the impedance of the transformer, this limitation isreflected in line 2).

6 Voltage Control and Dynamic Reactive Power PerformanceSome grid codes such as in the UK or Ireland require relatively high dynamic response of thereactive power output to voltage changes in the grid. In the UK, a STATCOM response isrequired within 200ms. In both grid codes, UK and Ireland, 90% of the steady state target

reactive power has to be reached within 1s. Stable operation has to be reached after 5s.

STATCOMs are able to react very fast, often considerably faster than required by the gridcodes. Figure 4 shows a measurement of a reactive power step response taken at aninstallation in Ireland. The stepped curve shows the reactive power reference, the smooth curvethe measured reactive power response. The sinusoidal trace shows the STATCOM outputcurrent to the grid. It can be seen that in this installation, the STATCOM is able to switch frommaximum under-excited mode to maximum over-excited mode within approximately 30ms. Although very fast, the response is remarkably stable and shows virtually no oscillations.The response time of the STATCOM can be tuned, depending on the control mode, the gridstability, the grid code requirements etc. In the best case, the STATCOM is able to reach fullreactive power output within a few ms.

1)1)

2)



/12

Figure 4 - Reactive power step response

In voltage control mode, such a fast response may not necessarily be requested. However, aftera voltage dip, reactive current shall be injected quickly in order to support the grid voltage.Figure 5 shows a measurement of a minor unbalanced grid disturbance recorded at aSTATCOM installation in Canada. The voltage dropped to around 90% of nominal voltage intwo phases. The reaction of the STATCOM is a compromise between re-balancing the grid anddistributing the available STATCOM output power on the three phases. It can be seen that theSTATCOM reacts almost immediately and helps to stabilize the grid voltage.

Figure 5 - Recording of a minor unbalanced grid disturbance

30ms

Qmax (12.5 Mvar)

Imax (326A)

Imin (326A)

Qmin (-12.5 Mvar)

0 20 40 120 140 160 180

Reactive power (referenceand measured value)

Primary (grid side)current in one phase

Time [s]



/12

7 Harmonic PerformanceSeveral standards are available that give the basis for harmonic performance requirements at agiven connection point. Important standards are [5] or [6] for wind turbines. In the UK, the

individual harmonic levels required in Engineering Recommendation G5/4 [7] are closely relatedto the indicative values given in [4]. However, some country specific exceptions are specified.During the acceptance tests of a 12.5Mvar STATCOM in the UK, the harmonic spectrum wasmeasured without the STATCOM operating in order to obtain the background harmonicspectrum at the site. Afterwards, the STATCOM was operated for several hours, and thevoltage harmonic measurement was repeated.

Figure 6 – Voltage harmonic spectrum without (left) and with (right) STATCOM in operation, andharmonic limits specified in [7]

Figure 6 shows the spectrum measured in one phase without (left) and with the STATCOM inoperation (right). The measurements are taken from a 12.5Mvar STATCOM installed in the UK,connected to the wind farm 33kV bus. The bars show the maximum measured amplitude of thevoltage harmonics. The grey dashes on top of the bars show the limits specified in [7].It can be clearly seen that each individual harmonic is well below the allowed level. Due to itstopology, contrarily to other STATCOM topologies present in the market ([11]), the PCS 6000STATCOM does not contribute harmonics below 27

th. The STATCOM contribution starts at the

29th harmonic. Due to the grid filter at the output of the STATCOM, the additional harmonic

distortion caused by the converter operation is very small and well within the limits of eachindividual harmonic. Consequently, the total harmonic distortion (THD) of the grid voltage ishardly affected by the STATCOM operation.

8 Operation after Acceptance

8.1 Ensuring reliable and robust operation

Since wind parks are often installed in remote areas, it is very important to offer to the industryhighly reliable and close to 100% available equipment that is furthermore almost maintenance-free. For the case that, during the operation of the equipment, some problems should arise,efficient service tools are necessary.The STATCOM as installed at several wind parks is designed for very high availability. Theconverter includes a closed-loop water cooling circuit. This allows a most compact, low-noiseindoor installation or a containerised outdoor option. The heat is transferred via a water-to-airheat exchanger to the outdoor air. Dusty or dirty air does not present a problem to theSTATCOM, and no filter air mats have to be exchanged. This cooling concept is well proven ina multitude of applications all over the world. It is very robust and requires virtually nomaintenance. Thanks to the redundant pumps and partial redundancy for the heat exchangerfans, the availability of the cooling circuit is extremely high.

STATCOMcontribution

Harmonic order n (multiple of 50Hz) Harmonic order n (multiple of 50Hz)

V o l t a g e h a r m

o n i c s ( i n % )

Lowest frequencySTATCOM contribution

Harmonic limits ([7])



/12

The STATCOM is not equipped with switched passive components. Only one circuit breaker isneeded to protect the complete STATCOM installation. Therefore, time consuming maintenanceand adjustments on circuit breakers for capacitor banks are obsolete.In case some troubles occur during operation, the STATCOM is equipped with powerful servicetools: A human-machine interface (HMI) is available that gives a quick overview of the

STATCOM status (see Figure 7). This tool can be accessed over the internet. It is very helpfulnot only during commissioning but also to support service personnel from remote.

Figure 7 - HMI overview of the STATCOM status

The same information is also made available on the interface to the wind park SCADA. TheSTATCOM can easily be embedded into the wind park control system. Commands, status andmeasurement information are exchanged.Furthermore, the STATCOM is equipped with an integrated transient recorder. This featureprogrammed in the STATCOM control software is triggered as soon as any abnormal condition,like e.g. a voltage dip, is detected. Not only predefined measurement values but also computedcontrol values and binary information is stored by the transient recorder before and after it istriggered. This function is extremely helpful to analyse system failures in order to quickly find theroot cause of the problem.

8.2 Example of trouble shoot ing

In the early time period after commissioning of a 12.5 Mvar STATCOM in the UK, there was anissue with the STATCOM control system that caused it to become instable with certainparameter settings. The problem was studied at the hardware-in-the-loop simulator. A modifiedcontrol software version was downloaded to the STATCOM from remote. During thesubsequent tests it was found that the problem was not completely solved. As a consequenceof resonance effect, the STATCOM failed and the transient recorder triggered. The data wasretrieved from remote. After the analysis of the measurement data, it became quickly clearwhich component was defective and what was the root cause for the failure. In a short time, theSTATCOM was repaired, the root cause of the failure rectified and finally the control softwaremodified. The STATCOM has been running very stable throughout the warranty period and is insuccessful and reliable operation today.



/12

9 Addit ional Value Adding Features

9.1 Smooth grid synchronization

In remote areas where wind parks are often installed, the grid is comparatively weak. If the

STATCOM output power is not much smaller than the grid short circuit power, flickerrequirements are very difficult to meet. During the magnetisation of the main transformer, theinrush current loads the grid in such a way that the voltage may drop considerably for a shorttime. This voltage drop might not be compatible with flicker requirements given in standardssuch as [1], [5], [6] or [8] for the UK.The STATCOM is optionally equipped with a unit connected to the auxiliary power supply.Before the STATCOM main circuit breaker is closed, the DC link is charged by this pre-chargingunit. Once charged up, the converter pulses are released and the STATCOM smoothlymagnetises the transformer. At the same time, the converter output voltage is synchronised tothe grid voltage. After a few seconds, the transformer is magnetised and the high voltagetransformer terminals are synchronised to the grid voltage. The circuit breaker can be closed.No inrush current will flow from the grid, and the grid voltage is unaffected.Figure 8 shows the voltage and the current in the moment the STATCOM is connected to the

grid. The measurements are made with a 24Mvar STATCOM, connected to the 33kV mediumvoltage grid in a wind park. The nominal current on the primary side of the transformer is 430A.It is seen that the inrush is not visible, and the current is under control immediately after thebreaker is closed. The grid short circuit power is between 284 and 525MVA.

0 1 2 3 4 5 6 7 8 9 10-40

-20

0

20

40

G r i d v o l t a g e [ k V ]

0 1 2 3 4 5 6 7 8 9 10-100

-50

0

50

100

150

S T A T C O M p

r i m a r y c u r r e n t [ A ]

time [ms]

Figure 8 - Grid voltage and STATCOM current after magnetizing the STATCOM transformer

and closing the breaker

It is important to understand the impact of the pre-charging unit to the auxiliary supply. Duringthe pre-charging period and especially the energising of the transformer, a peak load has to besupplied by the auxiliary transformer. This load may be about two to three times as high as thenormal auxiliary power supply needs of the STATCOM. It is however only needed for a fewseconds. The auxiliary power transformer does not need to be designed for the peak load, butthis overload scenario has to be taken into account. Furthermore, this fact needs to beconsidered when defining the protection settings for the auxiliary transformer.

9.2 Active voltage harmonic filtering

Another interesting feature is implemented in a STATCOM for a utility customer in Canada. Atthe customer site, important low-order voltage harmonics exist in the grid. Voltage source

converters as used in STATCOMs can principally be operated to actively filter certain



/12

harmonics. It is state of the art for active harmonic filters to compensate current harmonics.However, in certain cases, voltage harmonics have to be compensated.

The basic idea of voltage harmonic compensation is to inject a current with the same frequencyas the respective voltage harmonic. The amplitude and the angle of the compensating current

have to be chosen such that the voltage harmonics are compensated. This is the case if themultiplication of the injected current and the grid impedance, which corresponds to the“compensating voltage”, has the same voltage magnitude at the respective frequency andpresents a 180° phase shift with respect to the voltage harmonic that has to be compensated.Consequently, to define the magnitude and angle of the compensating current, the gridimpedance has to be known for the harmonic to be cancelled. However, depending on the gridconfiguration, the grid impedance for higher order harmonics can vary considerably inmagnitude and in angle.

By having a closer look at the grid impedance, it is found that the real part is always positive forharmonics with an order n>=2. In other words, the grid has always a positive resistivecomponent at higher order harmonics. This comes from the fact that the grid has losses.This resistive characteristic of the grid is used by the active voltage filter. In a first step, the filter

reacts with the assumption that the grid impedance is purely resistive and injects a current witha small amplitude and a 180° phase shift with respect to the measured voltage. Figure 9 showsthe initial condition for any frequency, when the filter is not active, as well as the variation in thegrid voltage due to the small current of the filter. UG0 is the grid voltage before compensation. IG0

shows the compensating current, which has a phase shift of 180° to the grid voltage. ΔU1 represents the voltage drop due to the compensating current IG0, where UG1 is the resulting gridvoltage. The results shown in Figure 9 are based on a grid impedance Z G as shown in thecomplex plane.

Figure 9 - Injection of current with 180° phase shift to voltage, represented by phasors in anorthogonal coordinate system rotating with the frequency of the respective voltage harmonics

It is seen that only if the resistive component of ZG is positive and greater than zero, the voltageamplitude is reduced. However, unless the grid impedance is purely resistive, this reduction isnot optimal, because the compensating voltage is not directly opposed to the voltage to becompensated.

By further increasing the current amplitude and keeping a 180° phase shift between thecompensating current and the measured voltage component, the voltage is further decreased,as is shown on the left graph in Figure 10. IG1 corresponds to the filtering current with increasedamplitude, which is opposed in phase to UG1. It is seen that the resulting voltage is furtherreduced to UG2.

This is illustrated on the graph on the right side of Figure 10, which shows the path of theharmonic voltage vector in the complex plane if the compensating current is increased and thephase difference between the filtering current and the measured voltage is kept at 180°. Thepath of the voltage on the right side of Figure 10 is found if the compensating current IG in theleft side of Figure 10 is further increased. The harmonic voltage theoretically approaches zero,but it does not follow an optimal path.



/12

However, it is practically not possible to completely eliminate the voltage harmonics: Zeroharmonic voltage is a singularity, since no more voltage is present to give a reference for thephase of the compensating current. This means in practice that the voltage harmonics can bedecreased to a minimal value depending on the measurement accuracy, but not completelyeliminated.

-0.2 0 0.2 0.4 0.6 0.8 1-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

real(VPCC

n ), p.u.

i m a g ( V P C C

n

) , p . u .

Harmonic voltage progression with resistive harmonic filtering

Path of the reduced voltage component

Maximum harmonic reductiondepending on measurement accuracy

Figure 10 - Change in grid voltage by assuming resistive grid impedance

The above described method has been successfully implemented. The reduction of harmonicvoltage components is visualized in Figure 11.

Figure 11 - Harmonic spectrum with active filter function deactivated (left) and activated (right)

Of course, there is a trade-off between standard STATCOM reactive power performance andthe amount of achievable compensation. Careful system studies need to be done in order to beable to design the STATCOM properly.

10 Conclusion

This paper describes different aspects of operational experiences of STATCOMs used ascontinuously acting, highly dynamic reactive power compensation equipment for wind parks.Measurements that confirm the satisfying operation of the STATCOM are presented.The importance of high availability is pointed out and measures taken in order to ensure thereliable operation of the STATCOM are highlighted. Furthermore, important service tools aredescribed. These tools support efficient trouble shooting by remote access to the STATCOMand its transient recorder files.Last but not least, optional value adding features such as inrush-free energising of thetransformer and active voltage harmonic filtering are presented.



/12

Table of f iguresFigure 1 - The STATCOM principle...............................................................................................2

Figure 2 – Example of a connection of the STATCOM to the wind park MV bus......................... 3

Figure 3 - Steady state reactive power requirements, design and measurements....................... 5

Figure 4 - Reactive power step response ..................................................................................... 6

Figure 5 - Recording of a minor unbalanced grid disturbance...................................................... 6

Figure 6 – Voltage harmonic spectrum without (left) and with (right) STATCOM in operation, andharmonic limits specified in [7] ...................................................................................................... 7

Figure 7 - HMI overview of the STATCOM status.........................................................................8

Figure 8 - Grid voltage and STATCOM current after magnetizing the STATCOM transformerand closing the breaker................................................................................................................. 9

Figure 9 - Injection of current with 180° phase shift to voltage, represented by phasors in anorthogonal coordinate system rotating with the frequency of the respective voltage harmonics 10

Figure 10 - Change in grid voltage by assuming resistive grid impedance ................................ 11

Figure 11 - Harmonic spectrum with active filter function deactivated (left) and activated (right)..................................................................................................................................................... 11

References[1] Maibach Ph., Wernli J., Jones P., Obad M., STATCOM Technology for Wind Parks to

Meet Grid Code Requirements, EWEC 2007[2] Steimer P.K., Apeldoorn O., Ødegård B., Bernet S., Brückner T., Very High Power IGCT

PEBB Technology, IEEE, 2005[3] National Grid Company plc, Guidance Notes for Power Park Developers, Grid Code

Connection Conditions Compliance: Testing & Submission of the Compliance Report,June 2005 – Issue 1 (http://www.nationalgrid.com/uk/Electricity/Codes/gridcode/associateddocs/)

[4] IEC/TR3 61000-3-6 (1996): Electromagnetic compatibility (EMC) – Part 3: Limits –Section 6: Assessment of emission limits for distorting loads in MV and HV powersystems – Basic EMC publication

[5] IEC 61000-2-12 (2003): Electromagnetic compatibility (EMC) – Part 2-12: Environment –Compatibility levels for low-frequency conducted disturbances and signalling in publicmedium-voltage power supply systems

[6] IEC 61400-21 (2001): Wind turbine generator systems – Part 21: Measurement andassessment of power quality characteristics of grid connected wind turbines

[7] Engineering Recommendation G5/4 (2001): Planning Levels for Harmonic VoltageDistortion and the Connection of Non-Linear Equipment to Transmission Systems andDistribution Networks in the United Kingdom

[8] Engineering Recommendation P28 (1989): Planning Limits for Voltage FluctuationsCaused by Industrial, Commercial and Domestic Equipment in the United Kingdom

[9] Viavan F., Sannino A., Romero I. and Maibach Ph., STATCOM for Wind Farms FaultRide Through Improvement and Grid Code Compliance, Windintegration Workshop,Madrid, 2008

[10] Ronner, B.: Verfahren zum Betrieb einer Umrichterschaltung sowie Vorrichtung zurDurchführung des Verfahrens, European Patent 08151808.6 , February 2008

[11] A. Cetin, M. Ermis, VSC based D-STATCOM with selective harmonic elimination, Industryapplications conference, 2007, 42

nd IAS annual meeting

[12] M. Molinas, J.A. Suul and T. Undeland, Improved grid interface of induction generatorsfor renewable energy by use of STATCOM, International conference on clean electricpower 2007

[13] I.A. Erimez & A.M. Foss, STATIC SYNCHRONOUS COMPENSATOR (STATCOM),Working Group 14.19, CIGRE, August 2000

[14] L. Xu, L. Yao and C. Sasse, Comparison of using SVC and STATCOM for wind farmintegration, IEEE International Conference on Power System Technology, Oct. 2006

[15] M. Aten, J. Martinez and P.J. Cartwright, Fault recovery of a wind farm with fixed speedinduction generators using a STATCOM, Wind Engineering, Vol. 29, No. 4, 2005

[public] abb operational experiences of statcoms for wind parks

Documents