US 20110118884Al (19) United States (12) Patent Application Publication (10) Pub. No.: US 2011/0118884 A1 MAYOR et al. (43) Pub. Date: May 19, 2011 (54) CONTROL OF ACTIVE POWER RESERVE IN (22) Filed: Nov. 12, 2010 A WIND-FARM Related US. Application Data (75) Inventors, Jesl'ls MAYOR pamplona (ES). (62) Division of application No. 11/842,585, ?led on Aug. David SOLE, Pamplona (ES); 21’ 2007' Jorge ACEDO’ Pamplona (ES); Publication Classi?cation Ainhoa CIARCAR, Pamplona (ES); Javier PEREZ BARBACHANO, (51) Int- Cl pamplona (ES); Mike] G05D 17/00 (2006.01) ZABALETA, Pamplona (ES); (52) US. Cl. ...................................................... .. 700/287 Susana SIMON, Pamplona (ES) (57) ABSTRACT (73) Assi nee INGETEAM ENERGY s A A method and system of active poWer reserve regulation in a g ' Navarra (ES) ’ ' " Wind farm With a communication network having a plurality of Wind turbines that provide an active poWer reserve in order to support eventual poWer grid contingencies and to deliver an (21) Appl, No.1 12/945,393 increase of poWer in case it is needed. I011 IOIU 101“ E0. F.O. 3°01 COMMUNICATION 300“ COMMUNICATION 300n F.O. ARI/M1 WTRC ARI/lwtu WTRC ARIIIIII , WTRC °/ P CPU COMMUNICATION ° ‘IIeIPIed . PROCESSOR AV_PWI1 AV_Pwtu AV-PWII IIO I SMOEFTMWOARRYE I NETWORK NETWORK NETWORK CONNECTION 1051 CONNECTION 1051 CONNECTION I05u+1 CONNECTION 105m 1061 NETWORK NETWORK COMMUNICATION BUS CONNECTION I06 CONNECTION 107 ARI/M1 ARI/lwtnI% Pra_teWdT I SpPcLI AWVt - P ---AV-Pwtn AV-PCL SpPcLI AV_PC|_ res . ' PCC WFCC CL \102 I03\ CPU PROCESSOR MEMORY & SOFTWARE Patent Application Publication May 19, 2011 Sheet 2 0f 7 US 2011/0118884 A1 A k sham 555g - 52mg? 61.2 35.2 55.2 5I2: » 9g>%<m Patent Application Publication May 19, 2011 Sheet 3 0f 7 US 2011/0118884 A1 A.lMQ 2z5_1 >2>. \w{a190 E382 @102 Egg: 025%.?I k 5% 55%-? 9.2 :55 25.2 E:?3 Patent Application Publication May 19, 2011 Sheet 4 0f 7 US 2011/0118884 A1 @325 324% Patent Application Publication May 19, 2011 Sheet 5 0f 7 US 2011/0118884 A1 /400 y% 10% H-22 F4IG. Av_Freq sp_Freq Patent Application Publication May 19, 2011 Sheet 6 0f 7 US 2011/0118884 A1 /503 /504 F5IG. US 2011/0118884 A1 May 19, 2011 CONTROL OF ACTIVE POWER RESERVE IN ful?ll the reactive poWer requirement. The ’241 application A WIND-FARM also describes a method to control a reserve of reactive poWer Which is available in case the electric utility demands it. CROSS-REFERENCE TO RELATED [0007] Conventional methods are knoWn to limit the active APPLICATIONS poWer output from a Wind-farm, for example, to adapt pro duction to the constraints of the evacuation capacity, i.e. the [0001] This is a divisional of US. application Ser. No. maximum poWer that can be delivered to the grid HoWever, 11/842,585, ?led Aug. 21, 2007. The entire disclosure ofthe prior application is incorporated by reference herein. these methods do not guarantee a reserve of active poWer. [0008] Consequently, there is a need for a strategy to guar FIELD OF THE INVENTION antee a reserve of active poWer. Such a reserve Would alloW Wind-farms to resemble conventional poWer generation [0002] Apparatuses, methods and articles of manufacture sources and thereby make it more convenient for the electric consistent With the present invention relate to the ?eld of Wind utility to stabiliZe the frequency and voltage of the grid. poWer generation, and, more particularly, advanced Wind farm poWer management. SUMMARY OF THE INVENTION BACKGROUND OF THE INVENTION [0009] It is an aspect of exemplary embodiments of the [0003] In an electric poWer grid (“grid”) it is necessary to present invention to provide a control of active poWer reserve continuously match the poWer consumption and generation in in an integrated manner taking into account the netWork pri order to keep the frequency and voltage Within the grid Within orities at each moment as Well as the effort demanded by the alloWed limits. The electric utility continuously monitors Wind turbines. This method in conjunction With the control of both magnitudes and must be able to issue commands to reactive poWer reserve described in US. application Ser. No. generation units in order to stabilize the electric poWer grid. 11/615,241 alloWs the complete control of the Wind-farm so This requires poWer generation units to be able to deliver an as to appear as a conventional poWer plant. increase of poWer if the Electric Utility demands it, and thus, [0010] It is an aspect of certain embodiments of the present the generation units must be able to maintain and manage a invention to provide Wind-farm control With a better regula reserve of active poWer (also knoWn as real poWer). More tion ability, such as being able to increase or decrease the speci?cally, taking S as the complex poWer, P as the real or active poWer supplied to the grid in order to maintain the active poWer and Q as the reactive poWer, the relationship frequency stability of the grid Which operates as an automatic S:P+iQ is generally satis?ed. global adjustment of poWer to control the frequency of the grid. DESCRIPTION OF THE PRIOR ART [0011] Thereby, the active poWer system described here is even able to manage an active poWer reserve in order to cope [0004] In the last feW years, Wind poWer generation has With eventual grid contingencies. In this Way, control of the increased considerably WorldWide. This groWth is Widely active poWer reserve is granted a key role in a Wind farm forecast to continue into the next decades, even as the industry poWer production strategy. and technology have arisen to a mature level in this ?eld. As [0012] According to one aspect of an exemplary embodi Wind farms groW in siZe and the total base of installed Wind ment of the present invention the Wind-farm controller capacity continues to increase, the importance of improving de?nes tWo operational modes for each Wind-turbine: both the poWer output quality and the grid stability becomes [0013] an active poWer observer mode (APOM); and a challenge of great importance to Wind developers and utility [0014] an active poWer reserving mode (APRM). customers alike. As more Wind energy is injected into the grid, it is highly convenient that Wind-farms behave as similar [0015] When a Wind-turbine is operated in APOM the as possible to other sources of conventional poWer genera poWer output is controlled in accord With the maximum tion, taking into account the particular nature of Wind. poWer available With the actual Wind conditions or, at least, [0005] From the point of vieW of the electric utility, it is Without regard to maintaining an active poWer reserve. In this important to accurately control the grid voltage and fre mode the Wind-farm controller does not impose any con quency. For these purposes, conventional poWer plants are straint in the active poWer generated by the Wind-turbine. required to supply extra active and reactive poWer When [0016] Alternatively, When a Wind-turbine is operated in needed by the Electric Utility. These demands are not cur APRM the Wind-farm controller issues a command that limits rently being ful?lled appropriately by Wind-farms and act as the maximum active poWer output from the Wind-turbine. constraints in the spreading of Wind poWer plants. Until noW, Therefore, the Wind farrn’s total active poWer production Will a Wind poWer plant could not be considered as a conventional be maintained beloW the maximum poWer available based on poWer plant because it has not been possible to accurately actual Wind conditions. Accordingly, there is additional determine an active poWer reserve due to the uncertainty of poWer potential available in the Wind farm based on the actual the Wind conditions. Conventional methods have not suc Wind conditions. Thus, the actual poWer output is loWer than ceeded in either achieving an accurate estimation of the active the maximum poWer output attainable based on the estima poWer reserve or an accurate response to the poWer demand. tion obtained from the Wind turbines operate in APOM. There is a need to develop an accurate method to generate an [0017] An aspect of an embodiment of the present inven active poWer reserve as the utility may demand it and in some tion is the optional use of at least one controlled load (CL) in cases has even offered to give a bonus to the project develop order to take advantage of the active poWer reserve in the Wind ers of such a method. farm. Such a controlled load could be used as an electric load [0006] US. application Ser. No. 11/615,241, the disclosure or as an energy storage unit such as a hydrogen generator, a of Which is incorporated herein by reference, describes a ?yWheel, etc. The controlled load is subordinated to the grid method to control reactive poWer in a Wind-farm in order to active reserve requirements. In case the grid needs extra US 2011/0118884 A1 May 19, 2011 power, the controlled load power consumption could be substation of the wind farm. The controlled load may be used ramped down or even switched off. as either an electrical load or as electrical storage unit. An [0018] In at least one embodiment, the wind farm central objective of this system is to follow a given setpoint of active control (WFCC) employs the wind-turbines operating in power reserve for the wind-farm as a whole. Moreover, this APOM to measure the power available in the wind-farm. In reserve of active power can be managed by the WFCC (100). contrast, wind-turbines operating in APRM are commanded [0029] Additionally, each WTRC (3001) through (300”) to achieve the desired active power reserve for the wind-farm. may be con?gured to communicate with the WFCC (100) using a communication bus (104) via network connections BRIEF DESCRIPTION OF THE DRAWINGS (1051) through (105”) and network connection (106) to com [0019] The incorporated drawings depict certain embodi municate various variables including active reserve mode ments of the invention. However, they should not be taken to commands ARMwti, relative power commands % Pwt_rat limit the invention to the speci?c depicted embodiment. ed_res, and active power measurements AV_Pwti. The Aspects of the present invention will become more apparent WFCC (100) also may be con?gured to communicate with by describing in detail illustrative, non-limiting embodiments the controlled load (102) via the communication bus (104) thereof with reference to the accompanying drawings, in and network connection (107). which: [0030] Wind Farm Central Control (WFCC) system [0020] FIG. 1: Illustrates an exemplary embodiment of a [0031] The Wind Farm Central Control (WFCC) (100) is in wind farm that has an active power reserve control system charge of satisfying the desired active power reserve (% topology and the hardware elements of the wind farm. Sp_Pres) of the wind farm. In one embodiment % Sp_Pres is [0021] FIG. 2a: Illustrates an exemplary embodiment of a de?ned as a percentage of the active power of the wind farm wind farm central control (WFCC) for the control of an active at the present moment. In a different embodiment % Sp_Pres power reserve in a wind farm. could be de?ned as the value of the desired reserve of active [0022] FIG. 2b: Illustrates an exemplary embodiment of a power related to the rated wind farm power, i.e., in absolute wind farm central control (WFCC) where the grid frequency units (eg kW). stability is an input to the optimization algorithm. [0032] Referring to FIG. 2a, which illustrates a WFCC 100, [0023] FIG. 3: Illustrates an exemplary embodiment of a the wind farm active power reserve setpoint (% Sp_Pres) can wind turbine relative control (WTRC). be received either from the electric utility or generated by the [0024] FIG. 4: Illustrates an exemplary embodiment WFCC according to several criteria prede?ned in an optimi wherein an optimiZation algorithm uses the active power Zation algorithm (201). For instance, power reserve schedul reserve to support the grid frequency. ing, grid stability and economic pro?t optimiZation based on [0025] FIG. 5: Is a ?owchart that illustrates method for the control of the active power reserve are some of the criteria showing the determination of the number of wind turbines in that may be taken into account in the optimiZation algorithm. APRM and APOM states. [0026] FIG. 6: Is a ?owchart that illustrates methods of [0033] In one embodiment, illustrated in FIG. 2a, for example, the WFCC (100) receives various information (206) operating wind turbines in a wind farm. used to determine the active power reserve setpoint (%). Such information (206) can include relevant tariff information DETAILED DESCRIPTION from the utility, e. g. kWh tariff depending on the time, short [0027] Aspects and features of the present invention and term demand, a bonus because of an active power reserve, methods of accomplishing the same may be understood more grid capacity, production optimiZation information, grid fre readily by reference to the following detailed description of quency deviations, production optimiZation, power reserve the exemplary embodiments and the accompanying draw requirements, grid voltage stability, etc. In one embodiment ings. The present invention may, however, be embodied in such information (206) can also include the grid frequency many different forms and should not be construed as being stability (216) as described in FIG. 2a and as shown in FIG. limited to the embodiments set forth herein. Rather, these 2b. The WFCC (100) includes an optimiZation algorithm embodiments are provided so that this disclosure will be (201) which can be based on economic pro?t optimiZation. thorough and complete and will fully convey the concept of Such an algorithm takes into account the aforementioned the invention to those skilled in the art, and the present inven inputs as well as pro?t optimiZation parameters to generate an tion will only be de?ned by the appended claims. Several active power setpoint % Sp_PresWFCC, for example in order drawings will be referenced only as illustration for the better to maximiZe the economic pro?t of the wind farm, according understanding of the description. Furthermore, the same ref to well known numerical optimiZation algorithms. This algo erence numbers will be used in the drawings and in the rithm also generates the SPPCL taking into account the afore description to refer to the same or like elements. mentioned inputs and the actual power consumption of the [0028] An exemplary topology of a wind farm with an controlled load, and the characteristics and constraints of the active power reserve system is shown in FIG. 1. This system controlled load. Providing power to this controlled load takes includes of a plurality of wind turbines (1011 through 101”) advantage of the active power reserve instead of not using it. and two subsystems: the wind farm central control (WFCC) In other words, instead of limiting the wind turbine output to (100), shown in detail in FIG. 2a and FIG. 2b, which can be maintain an active power reserve, the active power reserve located in the substation or point of common coupling (PCC) may be maintained by diverting the power constituting the (103), and the wind turbine relative control (WTRC) (3001 reserve or a part of it to a controlled load. The amount of through 300”), shown in detail in FIG. 3, which is carried out power diverted to the controlled load is then considered part in at least one of the wind-turbines in the wind farm (see 101 1 of the active power reserve. The controlled load can be one or through 101” in FIG. 1). FIG. 1. also shows a controlled load a plurality of different loads arranged in series or parallel or (102) which in this exemplary embodiment is located in the any other con?guration.