Simulación de la influencia del STATCOM en las pérdidas del sistema de potencia

The supply of growing electricity demand is possible through continuous technological advances and the expansion of national and international electrical systems. This scenario could introduce voltage drops and consequent changes in the reactive power flow throughout the electrical network. In order to control these problems, various strategies have been developed as a solution to improve the transport and distribution of electrical energy. One of them is the Flexible Alternating Current Transmission System (FACTS), and more specifically the STATic synchronous COMpensator (STATCOM). This paper investigates the influence and effectiveness of STATCOM to mitigate the losses in the transmission lines and its impacts on bus voltage drops. The simulations are performed using the software DIgSILENT PowerFactory and the results showed that STATCOM reduces the power system losses in an interval of 23.86% until 32.86%, and in addition, the STATCOM decreases the annual energy cost by 7.82% in the implemented test case.El abastecimiento de la creciente demanda eléctrica es posible a través de los continuos avances tecnológicos y la expansión de los sistemas eléctricos nacionales e internacionales. Este escenario podría introducir caídas de tensión y los consiguientes cambios en el flujo de potencia reactiva en toda la red eléctrica. Para controlar estos problemas se han desarrollado diversas estrategias como solución para mejorar el transporte y distribución de energía eléctrica. Uno de ellos es el Sistema Flexible de Transmisión de Corriente Alterna (FACTS), y más concretamente el STATic synchronous COMpensator (STATCOM). Este artículo investiga la influencia y efectividad del STATCOM para mitigar las pérdidas en las líneas de transmisión y sus impactos en las caídas de tensión de las barras. Las simulaciones se realizan utilizando el software DIgSILENT PowerFactory y los resultados mostraron que el STATCOM reduce las pérdidas del sistema de potencia en un intervalo de 23,86% hasta 32,86%, y además, el STATCOM disminuye el costo anual de energía en 7,82% en el caso de prueba implementado.

Combined Operations of SFCL and Optimal Reclosing of Circuit Breakers for Transient Stability Enhancement of Power Systems

This thesis proposes the coordinated operation of optimal reclosing of circuit breakers and superconducting fault current limiter (SFCL) for enhancing the transient stability of a multi-machine power system. Transient stability performance of the combined operation of optimal reclosing of circuit breakers and SFCL is compared with that of the combined operation of conventional reclosing of circuit breakers and SFCL. Moreover, to see the effectiveness of SFCL in improving the transient stability, its performance is compared with the static var compensator (SVC). Simulation results in Matlab/Simulink environment for permanent balanced and unbalanced faults at different points in the system indicate that the proposed combination of optimal reclosing of circuit breakers and SFCL/SVC can enhance the transient stability of the system well than the combined operation of conventional reclosing of circuit breakers and SFCL/SVC. Furthermore, the SFCL performs better than the SVC for the same operating conditions of the system

Simulación de la Influencia del STATCOM en las Pérdidas del Sistema de Potencia

The supply of growing electricity demand is possible through continuous technological advances and the expansion of national and international electrical systems. This scenario could introduce voltage drops and consequent changes in the reactive power flow throughout the electrical network. In order to control these problems, various strategies have been developed as a solution to improve the transport and distribution of electrical energy. One of them is the Flexible Alternating Current Transmission System (FACTS), and more specifically the STATic synchronous COMpensator (STATCOM). This paper investigates the influence and effectiveness of STATCOM to mitigate the losses in the transmission lines and its impacts on bus voltage drops. The simulations are performed using the software DIgSILENT PowerFactory and the results showed that STATCOM reduces the power system losses in an interval of 23.86% until 32.86%, and in addition, the STATCOM decreases the annual energy cost by 7.82% in the implemented test case.El abastecimiento de la creciente demanda eléctrica es posible a través de los continuos avances tecnológicos y la expansión de los sistemas eléctricos nacionales e internacionales. Este escenario podría introducir caídas de tensión y los consiguientes cambios en el flujo de potencia reactiva en toda la red eléctrica. Para controlar estos problemas se han desarrollado diversas estrategias como solución para mejorar el transporte y distribución de energía eléctrica. Uno de ellos es el Sistema Flexible de Transmisión de Corriente Alterna (FACTS), y más concretamente el STATic synchronous COMpensator (STATCOM). Este artículo investiga la influencia y efectividad del STATCOM para mitigar las pérdidas en las líneas de transmisión y sus impactos en las caídas de tensión de las barras. Las simulaciones se realizan utilizando el software DIgSILENT PowerFactory y los resultados mostraron que el STATCOM reduce las pérdidas del sistema de potencia en un intervalo de 23,86% hasta 32,86%, y además, el STATCOM disminuye el costo anual de energía en 7,82% en el caso de prueba implementado.

Utility Applications of Smart Online Energy Systems: A case for Investing in Online Power Electronics

The backbone of any power grid, the transmission and sub-transmission networks, should be flexible, robust, resilient and self-healing to cope with wide types of network adverse conditions and operations. Power electronic applications are making a major impact on the present and future state of power systems generation, transmission and distribution. These applications include FACTS (Flexible Alternating Current Transmission), HVDC (High Voltage Direct Current) in transmission and Custom Power devices in distribution. FACTS devices are some of the advanced assets that network planners can use to make the transmission grid become more flexible and robust. Many established research ideas to advance operations of these devices have been published in the open literature over the last ten years. The most recent publications in this field are reviewed in this thesis. A critical analysis of literature and existing conditions reveals a range of potentials that are ideal for development in Qatar’s increasingly strained electricity network. As a result of demand surge in Qatar in recent years and the forecast to grow in the same rate, the need for improvement in Qatar Power Transmission System (QPTS) is great and significant. Conventional planning and operational solutions such as conductor up-rating, and fixed series capacitors (FSC) are considered. However there are growing challenges on getting new rights of ways for new overhead lines and even corridors for new cables. Advanced FACTS devices are considered for dynamic control of power flows and voltages, such as TCSC (Thyristor Controlled Series Capacitor) and GUPFC (Generalized, Unified Power Flow Controller). The research in this thesis examines the potential for QPTS to improve and develop, with emphasis on increased output through integrated online energy systems, online FACTS and HVDC controllers based on synchrophasor measurements. The devices are modelled in Siemens PTI’s PSS®E software, through steady-state mode case study to investigate power flow control and voltage support. Comparison between similar FACTS technologies, such as SVC and STATCOM, is also presented. The improvement in power flow imbalance between transmission lines with different ratings and lengths is studied. The FACTS devices are tested for voltage support to enhance the network voltage profile and hence increase security and reliability to important industrial customers. Optimization techniques of the FACTS devices allocation and rating are generally discussed considering the voltage improvement and optimal power flow control. The results achieved showing the network improvement with using the FACTS are presented in the case studies. In a separate case study, applying medium voltage custom power devices to convert DC battery storage and photovoltaic energy into AC energy using a power conversion system is discussed. The dynamic mode of the STATCOM is modelled in QPTS in the succeeding case study using the same software and compared with the capacitor banks. This is followed by another case of HVDC analysis modelled with and without STATCOM present. The thesis discussed the real time operation and control of power system physical parameters in QPTS using capacitors, FACTS and HVDC. The key contribution of this thesis is the application and resting of all sorts of FACTS and HVDC in QPTS. The system wide area, coordinated control of FACTS (Online Power Electronics-OPE) is a new concept. Another major contribution is being able to look at a system wide approach for a transmission smart grid application. The results of thesis are presented in international conferences in USA, Hong Kong, France, Portugal, and locally in the Arabian Gulf (Dubai, Oman and Qatar). The thesis’s papers are listed in the ‘References’ section and in Appendix-F

Modelling load balance type static var compensator control system response

As power system interconnection becomes more prevalent, there has been an increase in use of thyristor controlled shunt connected compensation devices for dynamic power system compensation and power transmission capacity increase. A Static Var Compensator (SVC) functions as a variable reactance capable of operating in both the inductive and capacitive region as required on a cycle by cycle basis to provide compensation at the point of connection to the power system. Voltage regulation is the operational objective of most SVCs. Therefore, transient response of SVC control systems impacts overall power system performance and inappropriate settings may lead to voltage instability. SVCs are also commonly used to convert single phase load into balanced three phase load, thereby reducing negative phase sequence voltages and currents within the power transmission system. As most load balancing SVCs are consistently operated to their capacity, removal from service to apply and test control system setting changes impacts system regulation and stability. Therefore, model development of a load balancing type SVC control system to predict response to setting changes may provide an alternative to lengthy outages of SVC plant. This paper examines the theoretical basis of thyristor controlled shunt compensation, establishing conditions for voltage support and unbalanced load compensation. Load balancing type SVC control system model development and validation is documented

Modeling and dynamic stability of distributed generations

The objective of this dissertation is to develop dynamic models for distributed generations (DG), to investigate their impacts on dynamic stability of power distribution systems, and to design controllers for DGs to improve the dynamic stability of the integrated power distribution system.;A two-year distributed generation (DG) project at West Virginia University (WVU) evaluated the impact of various DG sources on actual distribution systems by performing computer simulations. The data is supplied by two regional electric utilities of two actual distribution systems each. In this project several important issues were investigated, including the availability of simulation tools and impacts of DGs connected to a distribution line under a variety of line operating conditions. Based on this preliminary research the further most interesting topics for continued research were raised.;The continued research has focused on deeper investigation, such as, modeling DG sources, evaluating their interaction and impacts, and improving the dynamic stability of the integrated power distribution system. Four specific DGs are studied in this dissertation: fuel cell power plant, wind turbine induction generator, gas turbine synchronous generator and diesel engine synchronous generator.;A full-order synchronous generator model represents the generator models of gas turbine generator and diesel engine generator. A simplified gas turbine model has been chosen to be implemented. A practical diesel engine for emergency use is modeled. The generator model of wind turbine induction generator is represented by a full-order induction generator. The rated power operating regime is considered for impacts evaluations and controller design. Two types of fuel cell models are developed. The first one is a model of already operational phosphoric acid fuel cell (PAFC) obtained through data fitting and the second one is dynamic model of solid oxide fuel cell (SOFC). Since fuel cells are connected to the electric power network via inverters, an inverter model has been developed.;Multi-DG controls are investigated in this dissertation. One DG control is fuel cell control, the other one is wind-turbine control. The control of fuel cell (SOFC) plant is through the inverter to adjust active power injection to the network during the transient time. The control of wind turbine generator is through the parallel connected SVC by adjusting reactive power injection to the system. Both control schemes are centralized.;Linear analysis methodologies are utilized in designing the controller. In the fuel cell control design, two pairs of critical modes are screened out using eigenvalue analysis. The participation factors of DGs with respect to the modes are calculated. Two specific lead-lag compensation units are designed to damp each mode separately. The gains of the two compensation units were then obtained via optimal control methodology. In wind turbine DG control design procedure, three rotor speed deviations are used as input signals while the controller outputs are the firing angle for the SVC and the pitch angle for the wind-turbine DG. An output feedback controller is designed. The dynamic load characteristic is also considered by modeling it as a structured uncertainty. mu-analysis is used to evaluate the robust stability of the controllers with respect to the uncertain parameters in the dynamic loads. The IEEE-13 node radial feeder with existing gas turbine and diesel engine DGs is used as a test system to evaluate the multi-DG control. The simulation results demonstrate the effectiveness of the control strategies.;Coordinated operation of all the DGs is investigated. Simulation results show that good configurations within DGs along the system can improve the system stability. Furthermore, the fast acting SVC is very effective in improving damping. Among the DGs investigated in this research, the fuel cell plant control is the best choice for the coordinated operation.;Finally, the approach to model a complete three-phase power distribution system is implemented. The impact of the developed DGs models is evaluated on a three-phase unbalanced distribution system. The three-phase 13-node IEEE system with gas turbine and diesel engine DGs is simulated using MATLAB/Simulink\u27s Power System Blockset (PSB). In the simulation, a three-phase thyristor controlled braking resistor (TCBR) is connected to absorb the surplus energy when the system is subjected to a disturbance. The three-phase dynamic simulation demonstrates the effectiveness of the proposed strategy

Effect of Unified Power Flow Controller on Power System Performance: A Case Study of Maryland 132/33/11 kv Transmission Station

This work examines the effect of Unified Power Flow Controller (UPFC) on power system performance using Maryland 132/33/11 kV transmission station as a case study. The transmission network consists of Alausa, Police Training College and Mushin 33 kV feeders and T1A-15 MVA, T2A-15 MVA and T3A-15 MVA 33/11 kV tertiary transformers with their respective peak load designated A-F. The developed model equations for the network without and with UPFC were implemented using Matlab/Simulink software (R2009b Version). The system’s performance was further examined by introducing a fault condition on D and E transformers. With A-F as 25, 37.5, 12.5, 12.5, 12.5 and 37.5 MW respectively, the average voltage improved from 0.95297, 0.93832, 0.93952, 0.93123, 0.91937 and 0.95297 p.u. respectively without the UPFC to 0.96142, 0.95560, 0.94782, 0.93838, 0.92755 and 0.96142 p.u. respectively when the UPFC was applied. Similarly, the average power improved from 3.55883, 6.85067, 9.8335, 12.4735, 14.74483 and 6.85067 MW respectively without the UPFC to 3.62233, 6.97133, 10.0095, 12.6952, 15.0113 and 6.97133 MW respectively with the UPFC. Also, for the earth fault introduced on D and E transformers, the average voltage improved from 0.4467 and 0.84005 p.u. respectively without the UPFC to 0.4507 and 0.8475 p.u. respectively with the UPFC. The average power similarly improved from 1.9435 and 5.3665 MW respectively without the UPFC to 1.9775 and 5.4625 MW respectively when the UPFC was applied. The results of this work showed that the application of UPFC on the Maryland transmission network appreciably improved the voltage and power profiles of the system

Selection of pilot buses for VAR support and voltage stability risk analysis

The primary objective of this thesis is to develop an index for the placement of reactive power support devices to ensure reliable operation of power systems. It is especially aimed at improving the load voltage profile and system security when loading is increased. Maintaining a good system voltage profile and security is an important aspect in voltage stability studies, especially with the ever increasing power consumption and system disturbances or contingencies. A new VAR support placement algorithm is developed using a standard continuation power flow and N-1 contingency criterion to pinpoint the best locations for the placement of VAR devices. The objective formulation takes into account the worst case voltage deviations at all load buses and at the same time maximizes the loading margin under different contingencies and loading levels. The algorithm has been tested on three standard benchmark test systems and demonstrates that the proposed algorithm improves considerably when compared to an existing method, for locating a suitable site for VAR support.;The secondary objective of this research focuses on the important aspect of estimating and quantifying the voltage collapse risk with and without the VAR support. It is motivated by the perception that VAR support guarantees additional security for the current system and is economically justifiable. A decision tree based model is designed for estimating the risk, which accounts for both the future system uncertainties and the consequences associated with violation of limits and voltage collapse. A case study on the standard IEEE 24 bus reliability test system investigates the different scenarios and evaluates the risk. The results prove that in spite of high installation costs, an SVC can make the system more reliable and ensure cost savings

Novel Night and Day Control of PV Solar Farm as STATCOM (PV-STATCOM) for Critical Induction Motor Stabilization and FIDVR Alleviation

Induction motors are globally used in several critical operations such as petrochemicals, mining, process control, etc., where their shutdown during faults causes significant financial loss. System faults can also lead to Fault Induced Delayed Voltage Recovery (FIDVR) causing service disruptions. Dynamic reactive power compensators such as SVC and STATCOM are conventionally employed to mitigate these issues, however, these are very expensive. PV solar plants are growing at unprecedented rate globally and are likely to be installed near such critical motors. This thesis presents several novel applications of a patented technology of utilizing PV solar plants, both during night and day, as STATCOM, termed PV-STATCOM, for mitigating above issues at about 50 times lower cost than equivalent-size STATCOMs. A reactive power modulation based PV-STATCOM control is developed to stabilize remotely located motor both during night and day in a realistic distribution feeder, even when reactive power support according to the pioneering German Grid code fails. This control was field demonstrated for first time in Canada (and perhaps in world) on the 10 kW PV solar system in the utility network of Bluewater Power, Sarnia, Ontario. Another novel control strategy based on active and reactive power modulation of PV-STATCOM is developed. MATLAB/PSCAD simulation studies show that the proposed control can stabilize remotely located motor much faster and with reduced real power curtailment than conventional strategies. A new real and reactive power control of PV-STATCOM is proposed to alleviate FIDVR. Electromagnetic Transients simulation studies on a realistic transmission network show that the proposed control on a 100 km remote solar farm can alleviate FIDVR and stabilize a cluster of motors for wide range of system parameters and operating conditions. PV-STATCOM can alleviate the need of local STATCOM for achieving the same objective. Comprehensive sensitivity and stability analysis of single and two distribution level PV-STATCOMs are performed with: i) equivalent and detailed PV-STATCOM model, and ii) PV-STATCOM control implemented at plant level and inverter level. The impact of modeling details, controller location and system parameters on controller interaction, are investigated