Governor Control for Kakabeka Falls Generating Station
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Governor Control for Kakabeka Falls Generating Station Robert E. Doan @ September 1999 A Thesis submitted in Ailfillment of the requinments of the Msc. Eng. Degree in Control Engineering Faculty of Engindg Lakeheaâ University Thunder Bay, Omûio National Library BiMiot ue nationale du Canah$B uWons and Acquisitions et 9Bib iogisphie Services wwices bibliographiques The author bas granted a non- L'auteur a accordé une licence non exclusive licence aliowing the exclusive permettant à la National Library of Canada to Biblioth&quenationale du Canada de reproduce, loan, distri'bute or sel reproduire, prêter, distniuer ou copies of this thesis in microform, venâre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/nlm, de reproduction sur papier ou sur fomiat électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thése. thesis .nor substantial extracts fkom it Ni la thèse ni des extraits substantiels may be printed or 0th-se de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son Damission. autorisation. Abstract This thesis examines a specific problem of govemor control on a set of hydroelectric airbines that suffer fkom severe wicket gate leakage. Linear mdeling and the steady state behavior of each turbine is investigated aad used to detennine the best means of spd conml. Findings show that a secondary water control device may be used with the wicket gates to alleviate the effects of leakage while the generator is disconnecteci from the transmission system. The control method results in two distinct modes of turbine operation, with each hving significantly diffmnt dynamic characteristics. A digital speed droop govemor scheme is wnsidered in a gain scheduling arrangement to amunt for the two operating modes. The stability boundaries of the govemor parameters are investigated, and an output fdback cost minimiration algorithm is used for obtaining controller gains- An outline of the software used to implement the govemor on an industriai programmable controller is presented, and the experimental performance for the turbines is compareci to the theoretically developed model. Table of Contents Abtract.................. ... ........................................................................................ .i. Tabk of Contents ................................................................................................... II I. Liit of Fiym& TiMa ....................................................................................... iii CBAPTER 1. STATION OVERVIEW....e...ee..........eee..........~...........e........ee......e....... 1 CHAPTER 2 O LINEAR MODELINC OF WROGENERATORS ......................9 CHAPTER 3 O SPEED DROOP GOVERNING ..e~..........................~........................26 CBAPTER O - FUTURE: WORK ..............................................................................SS List of Figures & Tables Figure 1 O 1 Kakabeka GS Electncal Ovewiew ................................................................. 3 Figure 1-2 Water Conveyance System ............................................................................. 4 Figure 1-3 Turbine Assembly ......................................................................................... 7 Figure 2- 1 Wicket Gate actuator Dynamics .................................................................15 Figure 2-2 Steaây State Turbine Characteristics ........................................................... 21 Figure 3- 1 Speed Droop Govemor Control ................................................................... -27 Figure 3-2 Govemor gstem Bode Plot O OOnline Mode .................................................. 29 Figure 3-3 Govemor System Bode Plat O ûffline Mode ...............................................30 Figure 3-4 Governor Stability Regions ..................................................................... 34 Figure 3-5 Govemor Coatrol System ............................................................................. 42 Figure 3-0 Generator 1 =Line Disturbance Response ................................................ 49 Figure 3-7 Generator 1 Simulated On-Line Disturbance Response ................................ 50 Figure 3-8 Generator 1 W icket Gate Setpoint Response .............................................. 51 Figure 3-9 Generator 1 Startup Sequence ...................................................................... 53 Figure 3-10 Generator 1 Shutdown Sequence .............................................................. 54 Table 2- 1 Generating Unit Constants ..................................................................... 22 Table 2-2 Mode1 Plvameters for Steady State Operating Points ..................................... 23 Table 3- 1 Sumrnary of Computed Governor Settings.................................................... -48 Chapter 1 Station Ovewiew 1.1 Introduction Kakabeka Falls GS is a small hydro-electxic generating station situated on the Kaministiquia river approximately 20km west of Thunder Bay, Ontario. The plant is owneâ and operateci by Ontario Power Generation, and is one of the oldest stations of its type in the province. Construction of the plant began in the late 1800's and was cumplete by 1904, during the early stages of Ontario's electrification. Although the plant is nearing its 100' year of srnice, fiequent capital reinvestment has allowed the facility to keep pace with modem electrical generating stations. In 1998 a new plant automation system was instaîled, to facilitate remote controi and monitoring. Before this time, many of the critical plant operations were dom mudly b y a plant operator. Wiithe newly instaîled equipment, Ontario Power Generation hoped to perform the following plant opetatio~sfkom its central operating & maintenance facility: Automtic unit start-up and shutdown of the genmors. Autodc genemor synchronisation to the power system. Automafitc contrd of ekrical power pmQuaionand wata usage. The automation system indled at the plant is bdon the Modiwn "Quantum" fmily of programmable logic controllas (PLC). A system of this type was chosen becsuse it is I adaptable to many industrial applications, it can handle a large numba of field wired I/0 signalis, and it aîlows the end user to tailor fit the software logic to specific design requirement S. This thesis deals primarily with one challenging aspect of the station automation: the design a digital govemor control algorithm tOr implemedrtion on the PLC. The rniccess of the entire project hhged on the abüity of the control system to provide adquate speed regulation of the gendguni& Ahhough this is a serightfhmd task a typid hydro generating stations, problems unique to Kakabeka quired fùrthcr review of the fmibility and design of this control bction. in this chapter an ovaview of the plant equipment and opaation is given, dong with the conditions that dethe task of spad govdng at Kakabeka unique. ui Chapter 2, a linear madel is formulateci for each of the plant generating units. Stdystate turbine behavior is investigated and used to determine the best means of operation. The chosen feedback control structure used for speed goveming is set out in Chapter 3. Tuning panmeten are derived based upon the stability boundaries of the closed loop system, and the govemor control aigorithm and experimeatrl data are presenteâ, to support the theorrticat development. 1.2 Piant EIectrical System Kskpbeka Generating Station contains four horizontdly mounted synchronous generators (see Figure 1-1) each co~lcctedto a Francis water-wheel turbine. Generators 1 through 3 are equivalent in size and rating, while generator 4 is slightly larger in capacity. Each of these units has a power transformer ~~t!Ctedduectly to the stator windings. The transfomers are configured in a Delta Y-Ground arrangement and provide voltage step- up Born 4kV at the generators, to the 2S.OkV distriiution bus. Power tiom the plant is transfemd to the ûntario's bulk electrical system via two 25.OkV feeders. A number of oil-filled cucuit bteakers provide switching and fault isolation for the genentors and distribution feeders. The generator breakers are useâ primarily for synchronizing and removal of individual generating units Eorn the power system. However, they also pmvide isolation in the event of an electrical fault. The line breakers are useâ to isolate the plant fiom the power system in the mnt of a feeder or station bus fault, and also serve as isolation points of electrical equipment whea routine maintenance is paforrned. Fwlt detection on the various pieces of electricd apparatus is achieved with high-speed protective relaying schemes located within the plmt. Gt -G3- 4iaaœmw 6350 KVA 9375 KVA O.= PF 0.80 PF ao KV 4.0 KV 34mfz 34 60Hz r17RpM UTlZPM Cl - C3 Tmi- ClTrrrlkwr 6000 KVA 10,000 KVA Figure 1-1 Kalubeka CS Electriul Overview 1.3 Water Conveyance System Kakabeka generating station is a "run of the rivet' type hydro plant; A dmlocated in a section of the Kaministiquia River forms a sdlhead pond to facilitate plant operation. The term "run of the river" is us4 because the plant water consumption must closely match river flows at dl times, in order to maintain sufficient water level for operation. The major element in the water wnveyance system is a 2hn long aqueduct, which is useû to bridge most of the gap ôetween the dam, and the powerhouse (See Figure 1-2). This single burieci concrete