Modelling of reduced GB transmission system in PSCAD/EMTDC

Energy and environmental issues are two of the greatest challenges facing the world today. In response to energy needs and environmental concerns, renewable energy technologies are now considered the future technologies of choice. Renewable energy is produced from natural sources that are clean and free; however, it is widely accepted that renewable energy is not a solution without challenges. An example of this can be seen in the UK, where there is much interest amongst generation developers in the construction of new large scale onshore and offshore wind farms, especially in Scotland. The stability of electric power systems is also an important issue. It is important to have full knowledge of the system and to be able to predict the behaviour under different situations is an important objective. As a result, several industrial grade power system simulator tools have been developed in order to estimate the behaviour of the electric power system under certain conditions. This paper presents a reduced Great Britain (GB) system model for stability analysis using PSCAD/EMTDC. The reduced model is based upon a future GB transmission system model and, hence, contains different types and mix of generation, HVDC transmission lines and additional interconnection. The model is based on the reduced DIgSILENT PowerFactory model developed by National Grid

Performance Evaluation of Fuel Cell and Microturbine as Distributed Generators in a Microgrid

This paper presents dynamic models of distributed generators (DG) and investigates dynamic behaviour of the DG units within a microgrid system. The DG units include micro turbine, fuel cell and the electronically interfaced sources. The voltage source converter is adopted as the electronic interface which is equipped with its controller to maintain stability of the microgrid during small signal dynamics. This paper also introduces power management strategies and implements the DG load sharing concept to maintain the microgrid operation in standalone, grid-connected and islanding modes of operation. The results demonstrate the operation and performance of the microturbine and SOFC as distributed generators in a microgrid. Keywords: Microgrid, Distributed Generation, Microturbine, Fuel Cel

Novel Controls of Photovoltaic (PV) Solar Farms

Solar Farms are absolutely idle in the night and even during daytime operate below capacity in early mornings and late afternoons. Thus, the entire expensive asset of solar farms remains highly unutilized. This thesis presents novel technologies for utilization of PV solar farm inverter in nighttime for providing multiple benefits to power systems, as well as accomplishing the same objectives during the daytime from the inverter capacity left after production of real power. The new technology transforms a solar farm inverter functionally into a dynamic reactive power compensator known as STATCOM, and termed PV-STATCOM. A novel coordinated control of PV-STATCOMs is proposed for loss reduction in a distribution network. The saved energy is substantial and can be used for powering several homes annually. The second novel PV-STATCOM control involves a temporary curtailment of real power production and utilization of the available reactive power capacity to prevent the instability of a critical induction motor load. The third novel PVSTATCOM control is employed to significantly enhance the power transfer limit of a long transmission line both in the nighttime and also during daytime even when the solar farm is producing a large amount of real power. A new technique for short circuit current management is developed for a conventional PV solar farm that can potentially solve the problem due to which several solar farms have been denied connectivity in Ontario. This thesis has contributed to two patent applications and presented first time implementations of another two filed patents. A generalized PV solar system model in EMTDC/PSCAD software has been developed and validated with manufacturer\u27s datasheet. Another contribution of this thesis is the first time harmonics impact study of the largest solar farm in Canada, in the distribution utility network of Bluewater Power, in Sarnia, Ontario. This thesis makes a strong case for relaxing the present grid codes to allow solar farms to exercise these novel controls. This technology can open up new avenues for solar farms to earn revenues apart from the sale of real power. This will require appropriate agreements between the regulators, network utilities, solar farm developers and inverter manufacturers

Modelling and Analysis of hybrid microgrids using PSCAD/EMTDC

El principal objetivo del presente trabajo es la realización de una simulación completa de una microrred utilizando el programa profesional PSCAD/EMTDC. Para poder completar esta tarea, primeramente es necesario modelar correctamente las distintas partes de la microrred. Teniendo esto en cuenta, una microrred real es seleccionada como referencia para el modelado y la simulación de la microrred de la que trata el presente trabajo. Tras esto, una vez que las diferentes partes de la microrred están operativas, se procede a la simulación de diferentes casos de estudio, los cuales van desde simulación bajo condiciones de funcionamiento aislado, hasta condiciones de falta, pasando por el funcionamiento conectado a la red y bajo condiciones de emergencia. Se ha llevado a cabo algunas simplificaciones del sistema debido a la falta de información y a la ausencia de esquemas eléctricos. Por lo tanto, una vez que la red ha sido modelada y simulada, los resultados son analizados y las conclusiones realizadas. Como apéndices se presentan, un presupuesto y una guía de usuario con el fin de ayudar a la comprensión de cuál es el procedimiento en las simulaciones de sistemas de potencia con el software empleado

Novel Control of PV Solar and Wind Farm Inverters as STATCOM for Increasing Connectivity of Distributed Generators

The integration of distributed generators (DGs) such as wind farms and PV solar farms in distribution networks is getting severely constrained due to problems of steady state voltage rise and temporary overvoltages (TOV). This thesis presents a first time application of a patent-pending PV solar farm control as a dynamic reactive power compensator (STATCOM), termed PV-STATCOM, for mitigating the voltage rise and TOV issues, and significantly enhancing the connectivity of a neighbouring wind farm both during night and day in a realistic distribution feeder in Ontario. The effectiveness of PV-STATCOM is demonstrated even if the solar farm is located 30 km away from wind farm on a common distribution line. The PV-STATCOM utilizes the entire inverter capacity in the nighttime and the inverter capacity remaining after solar power generation during daytime. A novel control of full converter based wind farm as Wind-STATCOM for substantially increasing the connectivity of a neighbouring PV solar farm is also described. The Wind-STATCOM employs the inverter capacity left after that needed for wind power production, both during night and day. Subsequently, a new combined application of PV-STATCOM and Wind-STATCOM to improve the connectivities of both solar farm and wind farm to significantly high levels in a common distribution feeder is presented. These studies have been conducted for the first time in known literature. Commercial grade software PSS/E and PSCAD/EMTDC are used to evaluate the steady state voltage profile and TOVs, respectively, in distribution feeder having different Reactance (X) /Resistance (R) ratios

Novel Night and Day Control of a PV Solar System as a STATCOM (PV-STATCOM) for Damping of Power Oscillations

Installations of large scale PV solar farms are rapidly increasing, worldwide. This is causing a growing apprehension that inertialess power injections from these inverter based generators will result in a decline in power system stability. Instead, this thesis presents novel applications of a patent pending technology whereby the PV solar farms actually help significantly increase system stability. A novel 24/7 (night and day) control of a large-scale PV solar farm as a dynamic reactive power compensator STATCOM, termed PV-STATCOM, is presented for damping low-frequency electromechanical power oscillations resulting in a significant improvement in power transfer capability of existing power transmission systems. A new real and reactive power modulation based control of PV-STATCOM is demonstrated during daytime that combines the functionalities of both a STATCOM and a Battery Energy Storage System (BESS) to provide significantly enhanced levels of power oscillation damping than that achieved by either a STATCOM or a BESS. The effectiveness of the proposed PV-STATCOM Power Oscillation Damping (POD) control techniques based on modulation of reactive power, real power or a combination of both is evaluated through both small signal and Electromagnetic Transients simulations studies. Participation factor analysis is utilized for selection of appropriate control signals and damping controllers. The POD controllers are designed through small signal Residue analysis and validated through Simplex Optimization technique in electromagnetic transient simulations. The efficacy of the proposed PV-STATCOM controls is demonstrated on three power systems: Single Machine Infinite Bus SMIB system, Two-Area system, and the 12 bus FACTS power system, which exhibit different power oscillation modes. New ramp up techniques for power restoration from solar farms are also presented, which are substantially faster than those specified by grid codes. A methodology for coordination of proposed PV-STATCOM controls with existing Power System Stabilizers (PSSs) on synchronous generators is further described for further damping enhancement. This thesis thus presents a novel technology that can not only help increase the penetration of large scale PV solar farms but utilize them for reducing the need for construction of expensive new lines or use of costly Flexible AC Transmission systems for stability improvement

Dynamic fault simulation of wind turbines using commercial simulation tools

This paper compares the commercial simulation tools: PSCAD, PowerFactory, Simpow and PSS/E for analysing fault sequences defined in the Danish grid code requirements for wind turbines connected to a voltage level below 100 kV. Both symmetrical and unsymmetrical faults are analysed. The deviations and the reasons for the deviations between the tools are stated. The simulation models are implemented using the built-in library components of the simulation tools with exception of the mechanical drive-train model which had to be user-modelled in PowerFactory and PSS/E

Modeling of wind energy conversion system using PSCAD/EMTDC

This paper aims to model a complete wind energy conversion system (WECS) connected to a grid. The motivation comes from the Distributed Generation System (DGS) installed at the Renewable Energy Lab at UMass Lowell. The objective of this work is to develop universal and standardized manufacturer independent textbook models. Manufacturer specific models are more accurate and detailed, but proprietary and non-disclosure agreements become an issue for research purposes. Since the wind turbines installed in the lab are VSWT (Variable Speed Wind Turbine) with Permanent Magnet Synchronous Generators (PMSG), so such a turbine system is modeled to represent them in general. PMSG requires very less maintenance and has high efficiency since it doesn't have rotor current and is used without a gearbox. Further, there are two more advantages: first, it has the capability of variable speed control due to the fact that its rotor speed can change in a large range; second, it's excitation system is independent of the grid and require any other excitation source. In addition to the turbine generator, other main components of WECS are also modeled namely: wind source model, wind turbine, permanent magnet synchronous generator and AC/DC/AC control. The equations governing these models are also discussed. The entire generation system is implemented on PSCAD/EMTDC and integrated to a grid and a basic fault analysis is done under different conditions. The proposed model can be used for research purposes on distributed generation issues. This model provides a good software simulation test bed for further research

Modelling of the Western University Campus Electrical Network for Infrastructural Interdependencies in a Disaster Response Network Enables Platform

The interdependencies that exist between multiple infrastructures can cause unexpected system behaviour when their component failure occurs due to large disruptions such as earthquake or Tsunami. The complexities of these interdependencies make it very difficult to effectively recover infrastructure because of the several challenges encountered. To overcome these challenges, a research program called Disaster Response Network Enabled Platform (DR-NEP) was initiated. This thesis deals with the modelling of electrical networks in order to study critical infrastructures interdependencies as a part of DR-NEP project. In first module of the thesis, the concept and understanding of interdependencies is presented. For studying the infrastructural interdependencies, three infrastructures are selected at Western campus: electrical power system, steam system and water systems. It is demonstrated that electrical infrastructure is the most significant infrastructure as all other infrastructures are dependent on electrical input. This thesis subsequently presents the development of a detailed model of the electrical power system of Western campus. This model is validated with actual measured data provided by the Western facilities management for different loading conditions and different feeder positions. Such a model has been developed for the first time at Western University. This model can be used not just for studying disaster scenarios but also for planning of future electrical projects and expansion of facilities in the Western campus. The second module of thesis deals with the different disaster scenarios, critical subsystems and the impact of appropriate decision making on the overall working of the Western campus, with a special focus on electrical power systems. The results from the validated electrical model are incorporated into the infrastructural interdependency software (I2Sim). A total of six disaster scenarios are studied; three involving the electrical power systems in collaboration with water and steam systems, and other three involving only the electrical power system. The study of interdependency during disasters is performed to generate a wiser decision making process. The results presented in this thesis are an important addition to the earlier work done in DRNEP project, which only involved three infrastructures: steam, condensate return, and water. In this iv thesis, the information on electrical networks which was earlier missing is provided through the validated electrical power model. It is demonstrated that decisions to reduce electrical power consumption on campus by evacuating campus areas are effective in stabilizing the hospital operations but not in maintaining Western business continuity. A decision to accommodate hospital activities according to power availability appears to be the better choice. The results presented in this thesis will help in a much better manner to pre-plan different preparedness strategies to deal with any future potential emergencies in the Western campus