Grid retaining control of wind power plants system using doubly-Fed induction generators by passivity -based method - Dang Danh Hoang

Cao Tiến Huỳnh và Đtg Tạp chí KHOA HỌC & CÔNG NGHỆ 128(14): 149 - 154 156 GRID RETAINING CONTROL OF WIND POWER PLANTS SYSTEM USING DOUBLY-FED INDUCTION GENERATORS BY PASSIVITY -BASED METHOD Dang Danh Hoang* College of Technology - TNU SUMMARY The surveying and evaluation of the quality of control method for wind power systems using Doubly-Fed Induction Generators (DFIG) is a highly important signification. A new designing methodology for the passivity-based nonlinear controller is applied to gain some results which are described in this paper as can be seen, to control the Doubly-Fed Induction Generators, to maintain grid retaining of system in syschronical fault case which lead to drop a part of grid voltage Key word: Passivity - based control , wind power, grid fault. Notation Notation Unit Meaning R(x) Attenuation matrix J(x) Matrix links blocks in system structure. G(x) Matrix represents input, output relation. Lr H Rotor’s induction. Tr, Ts s Timing constant of rotor and stator r,  rad/s Rotor’s radian frequency, mechanical angular speed of rotor sd, sq Wb Components d and q of magnetic flux stator rd, rq Wb Components d and q of magnetic flux rotor  Summing dissipated co- efficient. Lm H Mutual inductance between stator and rotor Abbreviation DFIG Doubly-Fed Induction Generators PĐSG Wind power generators. EL Euler - Lagrange PBC Passive based control NL Energy PREFACE* Recently, in our country as well as in over the world, controlling Doubly-Fed Induction Generators in Wind power generators system (PĐSG) is a considerative problem. Now, there are some researchers who using a few control methods, such as: accurate * Tel: 0912 847588 linearazation[9], backstepping[1] and had gotten positive results. We ourselves also published searching projects in this field [2, 3]. This article introduces achievement of passivity-based control method to control Doubly-Fed Induction Generators in the case of grid failure. In details: Control to ensure wind power generators using Double-Fed Three-phrases Induction Generators in grid tracking when symmetrical grid failure happened leading to drop apart of grid voltage avoiding grid clumble if the generators cut out of grid simultaneously. There will be established systems containing many wind power generators, therefore when the errors happen, generators all cut out of grid easily occurs grid clumble. Thus, controling grid tracking is very important when the errors occur. This study itself focused on dealing the problem mentioned above. PASSIVITY-BASED CONTROL METHOD Fundamental theory Passivity Based Control - PBC is controlling algorithm which its principle based on passitive characteristic of objects (open-system) target to change closed-system being passive with expective energy storage function. Consider a system  which has summing function of energy storage H(x,x) (positive difining), input turning vector u, output y and ignore disturbance. So that, delivery speed of Đặng Danh Hoằng Tạp chí KHOA HỌC & CÔNG NGHỆ 128(14): 155 - 160 157 energy for system will be yTu. That could be passivity if: T T 0 energy storage energy input ( ) (0)dt H T Hy u   (1) where x = (x1,x2,..,xn)T and x is state vector and state derivative vector of system. Means that : u  y defining a passive relation using summing energy storage function ( , )x xH . If u = 0 then 0H  , system’s energy is invariable, so that it’s stable following Lyapunov, H is considered as Lyapunov function. If the system is tight passive then it could be asymptotical stability Lyapunov at origin cause of H is negative determination. Control System Structure Arccoding to [2, 4, 6], the system contains 2 basic control sections, as figure 1. Control from generators side using Doubly - fed induction machines - DFIG. Control from grid side Figure 1. Structure diagram of generators system using DFIG NLPL: Grid side inverter, NLMP: Generators side inverter, MĐC: On/Off switch, IE: Speed measurer. Applied to design controller Design Rotor’s current controller in generator side To apply this method, we divide gerenator’s rotor into two sections: electrical dynamics (energy function He, NL) and mechanical dynamics (energy function Hm) - Hình 2. Figure 2. Analysis DFIG to dynamic of electric and mechanic Figure 3. Structure principle diagram of controlling MĐKĐBNK by using PBC Then, by putting dynamic equations into EL equation, so the equations turn to passivity [11, 12]. From firgure 2, we construct pricipal diagram of control structure following passivity based method as showed in figure 3 and for specifically in figure 4. Figure 4. Structure of current vector controller PBC including 2 functional blocks Using the method taking controller into electrical dynamic system and interaction of He Hm ir m M mW  - - urPBC PBC IR e H m H (-) (-) (-) mW (sức gió) mG  PBC r u ri ri PBC I R : Current controller using PBC Transformer 3~ 3 ~ = Controller IE MĐ C u N us DFIG UDC ir is n iN NLPL NLMP = 3 ~ MĐKĐBNK (-) (-) e H m H (-) mW (wind power) mG  PBC r u * r i Calculate ur * based on function NL expectation He * Calculate attenuation coefficients D() us r s (-) * r u ( )D  ri Controller PBC I R r i r i Đặng Danh Hoằng Tạp chí KHOA HỌC & CÔNG NGHỆ 128(14): 155 - 160 158 mechanical dynamic system, so that closed- system is sastified EL equation, gotten: ( )( - )PBC D  * *r r r ru u i i (2) Where: 2 2 0 0 4 m r L D( ) d , R ,d (3) As in [1, 4] system of equations descirbe rotor current model of (DFIG) after separated in coordinate axes dq as: ' ' ' ' 1 1 1 1 1 ( ) . 1 1 1 . . 1 1 1 1 1 ( ) 1 1 1 . rd rd r rq sd r s s rdsq sd r m rq rq r rd sq r s s rq sqsd r m di i i dt T T T u u L L di i i dt T T T u u L L                                                        (4) To establish control problem, named ir is control variable, with expective value is ir* - taking from moment controller mG and cos. Passivity based controller EL is established following (2). Control signal is determined: * * * * ( ).( ) ( ).( ) rd rd rq rq PBC rd rd PBC rq rq u u D i i u u D i i         (5) Where: ; rd rq PBC PBCu u : Voltage from PBC controller created (following d and q). urd*; urq*: expecting rotor voltage of generator (following d and q), defined by (4). Figure 5. Generator control system DFIG in Wind Power Generator (PĐSG) system using Passivity – Based Controller From DC intermediate circuit Controller DCMM Grid Đặng Danh Hoằng Tạp chí KHOA HỌC & CÔNG NGHỆ 128(14): 155 - 160 159 1450 n_ref n mL Turbine Sine Wave Signal 1 Signal Builder Tr Tm Source K5 Sy nch Ti Fehler Udc Unetz Ustator IStator Enc Inetz Irotor I_kurzschluss I_haupt Mo hinh MF [n] u_dc u_netz u_stator i_stator enc i_netz i_rotor I_phu I_chinh theta_r ird* irq* omega_n indq_ist undq_ist theta_n udc_ist irdq_ist isdq_ist usdq_ist theta_s omega_s omega_m Chuan_hoa k_5 Rec Inv Sy nchout K5 Cac tin hieu dieu kien omega_n indq_ist undq_ist theta_n udc_ist IF Tabc DC Check Bo dieu khien phia luoi Sy nch IF udc_ist theta_n undq_ist omega_n irdq_ist isdq_ist usdq_ist theta_s omega_s omega_m Tabc theta_r ird* irq*1 Bo dieu khien MF By using the method mentioned above, we have rotor current controller following 2 sections: * * * * * * * 1 1 ( ) 1 . ( ' ' ) 1 . ( ).( ) rdPBC rd r r rd r s r r rq r sd s sq s r sd rd rd m di u L L i dt T T L i L T T L u D i i L                       (6) * * * * * * * 1 1 ( ) 1 ( ' ' ) 1 . ( ).( ) rq rq rq rd sq sd sq PBC r r r s r r r s s r rq rq m di u L L i dt T T L i L T T L u D i i L                       (7) As the result of passive based current controller, we see that it guaranteed the chanel seperation using compensated cross- linking by 2 components: r.ird* and r.irq* as well as compensating others parameters such as: grid voltage, stator flux, rotor speed and involve integral composition to reduce static errors. From (6), (7) and figure 4, we determine by using general control structure in generator side as figure 5 showed. Design controller in grid side Due to grid side requirement is stable control the voltage uDC providing for middle DC circuit. Therefore, this journal also gives a simple design method called normally linear Dead – Beat method [1, 3, 4]. Diagram and illustrative result using Matlab – Simulink – Plecs Illustrate the generator having parameter below: Pđm = 1,1 KW Uđmr = 345 V Rr = 3.7  Uđms =220/380(/) nđm =950 V/ph Ls = 0.013H fđm = 50 Hz Rs =4.2  Ls = 0.0089H zp = 3 Cosđm =0.657 Lm = 0,34H J = 0.064Kgm2 Iđm = 3,5A Identification: VM Vietnam Figure 6. Illustrative diagram of wind power generator system using DFIG In case, voltage droping (symmetrics) decreasing 10%, n = nđm =950 rpm; Applying control step moment from m=-3Nm to 0Nm and cos step down cos = 0.7 to 0.436 (sin = 0.9) for grid tracking: Figure 7. Grid voltage when drop out 10% Figure 8. Moment when grid drops out 10% Figure 9. Cos when grid drops out 10% Đặng Danh Hoằng Tạp chí KHOA HỌC & CÔNG NGHỆ 128(14): 155 - 160 160 Figure 10. Rotor current when grid drops 10% In case, voltage droping (symmetrics) decreasing 50%, n = nđm =950rpm; Applying control step moment from m=-5Nm to 0Nm and cos step down cos = 0.7 to 0.436 (sin = 0.9) for grid tracking: Figure 11. Grid voltage when drop out 50% Figure 12. Moment when grid drops out 50% Figure 13. Cos when grid drops out 50% Figure 14. Rotor current when grid drops 50% CONCLUSION - The paper has given a new control algorithm adding to [3]. - Illustrative result showed that rotor current controller had controlled sections: ird, irq follow up set points ird*, irq* when grid droped out (symmetrics) leading to voltage drop out from 10% to 50% of grid voltage and rotor angle frequency when curent controller PBC is fluctuative then working stability. When the failure finished, system return to stable (figure 7, 8, 9, 11, 12, 13, 14). The illustrative showed the stability of PBC controller when error occurs. Addition, it identicates the guaranteed control quality of system. REFERENCES 1. Cao Xuân Tuyển: "Tổng hợp các thuật toán phi tuyến trên cơ sở phương pháp backstepping để điều khiển máy điện dị bộ nguồn kép trong hệ thống máy phát điện sức gió", Luận án tiến sĩ kỹ thuật, Đại học Bách khoa Hà nội, 2008. 2. Đặng Danh Hoằng: "Hoà đồng bộ máy phát điện lên lưới bằng phương pháp điều khiển passivity–based", Tạp chí KHCN đại học Thái nguyên, 2010 3. Đặng Danh Hoằng, Nguyễn Phùng Quang, "Thiết kế bộ điều khiển dựa trên thụ động "Passivity - based" để điều khiển máy phát điện không đồng bộ nguồn kép", Tạp chí KHCN các trường đại học kỹ thuật, số 76, năm 2010. 4. Ng.Ph.Quang, A. Dittrich (2008) Vector Control of Three - Phase AC Machines - System Development in the Practice. Springer Heidelberg Berlin.. 5. Ng.Ph.Quang: “Matlab  Simulink dành cho kỹ sư điều khiển tự động”. Nxb Khoa học và Kỹ thuật, Hà nội, 2004. Đặng Danh Hoằng Tạp chí KHOA HỌC & CÔNG NGHỆ 128(14): 155 - 160 161 6. 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TÓM TẮT ĐIỀU KHIỂN BÁM LƯỚI HỆ THỐNG PHÁT ĐIỆN SỨC GIÓ SỬ DỤNG MÁY PHÁT KHÔNG ĐỒNG BỘ NGUỒN KÉP BẰNG PHƯƠNG PHÁP TỰA THEO THỤ ĐỘNG Đặng Danh Hoằng* Trường Đại học Kỹ thuật Công nghiệp – ĐH Thái Nguyên Việc khảo sát, đánh giá chất lượng phương pháp điều khiển cho hệ thống máy phát điện sức gió sử dụng máy điện không đồng bộ nguồn kép có một ý nghĩa hết sức quan trọng. Bài báo trình bày kết quả nghiên cứu áp dụng phương pháp thiết kế bộ điều khiển phi tuyến tựa theo thụ động (passivity – based) để điều khiển máy phát điện không đồng bộ nguồn kép, đảm bảo bám lưới khi xảy ra lỗi lưới đối xứng ở xa gây sập một phần điện áp lưới. Từ khoá: Điều khiển tựa theo thụ động, sức gió, lỗi lưới Ngày nhận bài:18/9/2014; Ngày phản biện:05/11/2014; Ngày duyệt đăng: 25/11/2014 Phản biện khoa học: PGS.TS Lại Khắc Lãi – Đại học Thái Nguyên * Tel: 0912 847588