755 research outputs found

    Analysis of the contribution of wind power plants to damp power system oscillations

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    Wind power has emerged as one of the most promising renewable energy sources. The very penetration levels of wind energy in power systems have altered several aspects of power system operation, such as system stability. Owing to the large penetration of wind power, transmission system operators (TSOs) have established special grid codes for wind farms connection. These grid codes require wind farms to provide ancillary services to the grid such as frequency and voltage regulation. In the near future, the capability of damping power system oscillations will be required. As a result of the development of such requirements, the concept of wind power plant (WPP) arises being de ned as a wind farm which is expected to behave similarly to a conventional power plant in terms of power generation, control and ancillary services. As future grid codes will require power oscillation damping contribution from wind power, the thesis is mainly focused on the analysis of the power system stabilizer (PSS) capability of wind power plants. The change produced by wind power plants based on di erent wind turbine technologies on power system small signal dynamics is analysed to determine their possible contribution to damp oscillations. The eff ect of the distance from the tie line to the wind power plant on the controller response and the influence of wind power plants proximity to synchronous generators are demonstrated to be critical factors. At this point several questions are raised as: What are the most critical factors? How can be ensure a proper contribution, at least the best possible response? Can it be ensured to be independent to the power system and the controller selected? To answer these questions, this thesis conducts research on proper selection of input-output signal pairs to damp out electromechanical oscillations using wind power plants without drawing attention to a particular control design. This is necessary conclusions about the power system independently of a particular controller. The capability to damp is an intrinsic characteristic of the system and should not be a ected by a particular controller (PSS). Firstly, di erent analysis techniques are compared, considering both controllability and observability measures and input-output interactions. This enables recommendations to be drawn so as to the selection of the the best signal pairs to damp power system oscillations considering di erent approaches, such as single-input single-output (SISO) and multivariable control (MIMO). Second, a new criterion to select the best input-output signals used by a PSS based on WPPs is presented, considering explicitly local and remote signals in the analysis. Taking into account fundamental design limitations and using controllability and observability concepts, the criterion is able to identify the most suitable pair of input-output local signals without consider any particular controller. Finally, due to the increase of wind power generation - including o shore locations - and the concept of an interconnected Pan-European network, a new o shore wind power plant AC network similar in design to the European SuperGrid \SuperNode", is analyzed. The cost e ect of choosing a nonstandard operating frequency on the o shore AC network is investigated. As the o shore AC network is isolated from onshore networks through the use of HVDC links, it may be operated in an asynchronous fashion and at a suitable frequency. The cost associated with operating the network at a fixed frequency in the range 20 to 120 Hz is investigated, focusing on the frequency-cost-scalings of electrical devices (such as cables, transformers and reactive compensation) and the related o shore infrastructures,L'energia e olica s'ha convertit en una de les fonts d'energia renovable m es prometedores. Actualment, l'elevat nivell de penetraci o de l'energia e olica a la xarxa el ectrica ha conduï t a la modi caci o del comportament de diversos aspectes d'aquesta, com per exemple, l'estabilitat. Degut a aquesta gran penetraci o, els operadors de xarxes de transmissi o (TSOs) han establert procediments d'operaci o especials per a la connexi o de grans parcs e olics. Aquests codis requereixen als parcs elics que realitzin serveis auxiliars al sistema el ectric com, per exemple, la regulaci o de freqü encia i la regulaci o de la pot encia reactiva. En un futur proper, la capacitat dels parcs e olics per esmorteir les oscil lacions del sistema de pot encia es requerir a (en l'actualitat ja existeixen esborranys de nous procediments d'operaci o que ho inclouen). A causa d'aquest requeriments, el concepte de central de generaci o d'energia e olica es de neix com un parc e olic que s'espera que es comporti de manera similar a una central de generaci o el ectrica convencional en termes de poder realitzar tasques tals com generaci o, control i serveis auxiliars. Ja que un futur requeriment dels operadors de xarxa ser a la contribuci o de l'energia e olica en l'esmorteiment de les oscil lacions de pot encia, en aquesta tesi s'estudia la capacitat de les centrals e oliques per actuar com estabilitzador dels sistemes el ectrics de pot encia. A m es a m es, s'analitza l'efecte de les centrals d'energia e olica al comportament din amic del sistema el ectric considerant l'estabilitat de petita senyal, per a determinar quina podr a ser la possible contribuci o proporcionada per aquestes tecnologies. S'ha estudiat que l'efecte de la dist ancia des d'el punt de connexi o amb la central d'energia e olica a la resposta del control estabilitzant i la influ encia de la proximitat de les centrals e oliques als generadors s ncrons s on factors cr tics. D'aquest fet surgeixen algunes preguntes com: Es aquest el factor m es cr tic? Com es pot assegurar una contribuci o adequada, si m es no la millor resposta possible, per ajudar a estabilitzar el sistema el ectric? Es poden asegurar quina ser a la contribuci o a l'estabilitat del sistema el ectric independentment de la xarxa i l'esquema de control escollit? Per respondre a aquestes preguntes, aquesta tesi ha realitzat investigacions sobre l'adequada selecci o de parells de senyals d'entrada-sortida per esmorteir les oscil lacions electromec aniques amb centrals e oliques evitant dissenyar el controlador i propossant met odes f acilment adaptables a qualsevol sistema el ectric. En primer lloc, s'han comparat diferents t ecniques d'an alisi tenint en compte tant les mesures de controlabilitat i observabilitat com les interaccions entre les senyals d'entrada i sortida. D'aquesta comparaci o, certes recomanacions es donen a l'hora de seleccionar els millors parells de senyals per esmorteir les oscil lacions del sistema el ectric de pot encia considerant diferents esquemes de control com ara entrada unica sortida unica (SISO) i control multivariable (MIMO). En segon lloc, s'ha proposat un nou criteri per seleccionar les senyals d'entrada i sortida utilitzades per un control estabilitzador per centrals d'energia e olica. On, a difer encia amb anteriors met odes de selecci o proposats, el criteri presentat considera expl citament tant senyals locals com senyals remotes dins el seu an alisi. Aquest criteri es capa c d'identi car la parella de senyals locals d'entrada i sortida m es adequada sense realitzar el disseny del controlador, considerant tant les limitacions fonamentals del disseny del controlador imposades per el sistema com els conceptes de controlabilitat i observabilitat. Finalment, a causa del augment de la generaci o d'energia e olica, principalment en localitzacions marines, i al concepte d'una xarxa el ectrica comuna Pan-Europea, s'ha realitzat l'an alisi d'un nou concepte de xarxa en corrent altern (AC) dins de les centrals d'energia e olica marina, amb un disseny similar al concepte investigat a la Super-Xarxa Europea \Supernode". En aquest treball s'ha investigat l'efecte que t e en els costos la tria una freqüencia nominal d'operaci o no est andard en dita xarxa en corrent altern. La xarxa en AC que es forma entre les turbines e oliques i el convertidor de transmissi o es aï llada tant de les xarxes terrestres per l' us d'enlla cos en corrent continu (HVDC) com de la pr opia de les turbines per el convertidor que porten incorporat. Aquest fet implica que aquesta xarxa pot ser operada sense sincronitzar a qualsevol freqüencia. En aquesta tesi, s'ha estudiat quin es el cost associat amb l'operaci o de la xarxa a una freqü encia fi xa dins del rang de 20-120 Hz, focalitzant principalment en l'escalat del costos dels diferents elements el ectrics (com ara cables, transformadors i compensaci o reatviva i infraestructures necessaris en instal lacions marines respecte la freqüencia

    Review of Power System Stability with High Wind Power Penetration

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    Heuristic optimization of supplementary controller for VSC-HVDC/AC interconnected grids considering PLL

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    This paper presents a new approach to enhance the dynamic responses of AGC in power systems by means of heuristic optimization of VSC-HVDC supplementary controllers. The upcoming power electronics-based VSC-HVDC transmission systems offer new features that would be advantageous for improving the frequency control and thus for enhancing the stability of the transmission grids. In this paper, the parameters of the proposed control modulation are tuned using Genetic Algorithm and Simulated Annealing methods. The performance of the proposed intelligent based tuning approach is assessed through MATLAB simulations for an AC/DC interconnected system. For the sake of detailed analysis, the effects of PLL and frequency measurements are also included in the VSC-HVDC system modeling. Furthermore, to show merits of the proposed strategy, a comparison between AC and DC transmissions is presented.Peer ReviewedPostprint (author's final draft

    Coordinated Damping Control Design for Power System With Multiple Virtual Synchronous Generators Based on Prony Method

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    With more renewables integrated into power grids, the systems are being transformed into low inertia power electronic dominated systems. In this situation, the virtual synchronous generator (VSG) control strategy was proposed to deal with insufficient inertia challenge caused by the reduction of synchronous generation. However, as the VSG control method emulates the dynamic behavior of traditional synchronous machines, the interaction between multiple VSG controllers and synchronous generators (SGs) may cause low-frequency oscillation similar to that caused by the interaction between multiple SGs. This paper reveals that the system low-frequency oscillatory modes are affected by multiple VSGs. Then Prony analysis is utilized to extract the system mode information which will be subsequently used for VSG controller design, and a decentralized sequential coordinated method is proposed to design the supplementary damping controller (SDC) for multiple VSGs. The system low-frequency oscillation is first analyzed based on a modified two-area system with a linearized state-space model, and a further case study based on a revised New England 10-machine 39-bus system is used to demonstrate the effectiveness of the proposed coordinated method for multiple VSGs

    Passivity - Based Control and Stability Analysis for Hydro-Solar Power Systems

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    Los sistemas de energía modernos se están transformando debido a la inclusión de renovables no convencionales fuentes de energía como la generación eólica y fotovoltaica. A pesar de que estas fuentes de energía son buenas alternativas para el aprovechamiento sostenible de la energía, afectan el funcionamiento y la estabilidad del sistema de energía, debido a su naturaleza inherentemente estocástica y dependencia de las condiciones climáticas. Además, los parques solares y eólicos tienen una capacidad de inercia reducida que debe ser compensada por grandes generadores síncronos en sistemas hidro térmicos convencionales, o por almacenamiento de energía dispositivos. En este contexto, la interacción dinámica entre fuentes convencionales y renovables debe ser estudiado en detalle. Para 2030, el Gobierno de Colombia proyecta que el poder colombiano El sistema integrará en su matriz energética al menos 1,2 GW de generación solar fotovoltaica. Por esta razón, es necesario diseñar controladores robustos que mejoren la estabilidad en los sistemas de energía. Con alta penetración de generación fotovoltaica e hidroeléctrica. Esta disertación estudia nuevas alternativas para mejorar el sistema de potencia de respuesta dinámica durante y después de grandes perturbaciones usando pasividad control basado. Esto se debe a que los componentes del sistema de alimentación son inherentemente pasivos y permiten formulaciones hamiltonianas, explotando así las propiedades de pasividad de sistemas eléctricos. Las principales contribuciones de esta disertación son: una pasividad descentralizada basada control de los sistemas de control de turbinas hidráulicas para sistemas de energía de múltiples máquinas para estabilizar el rotor acelerar y regular el voltaje terminal de cada sistema de control de turbinas hidráulicas en el sistema como, así como un control basado en PI pasividad para las plantas solares fotovoltaicas

    A Parameter Alternating VSG Controller of VSC-MTDC Systems for Low Frequency Oscillation Damping

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    DC STATCOM in multi-terminal DC distribution power system

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    Sub-synchronous Oscillation Characteristics and Analysis of Direct-drive Wind Farms with VSC-HVDC Systems

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