Electromagnetic transients of a micro-turbine based distributed generation system

According to the characteristics of double fed asynchronous generator rotor energy flow, research and design based on the DSP control with two-way flow of energy function of Dual PWM converter and discusses the grid side converter control method of Dual PWM converter in particular. The wind turbine simulation model is established by using the electromagnetic transient PSCAD/EMTDC software. The simulation system is used to simulate the P, Q decoupling control and maximum wind energy tracking control of the generator. Wind is a natural phenomenon generated by the solar radiation heat, the earth's surface caused by uneven heating of the atmosphere. It is estimated that only 1% of the wind on the ground will be able to meet the needs of the world's energy. With the continuous improvement of the level of wind power generation technology, the cost of wind power gradually reduced, considering environmental benefits, the cost will be close to the cost of coal-fired power generation. Therefore, great efforts to develop wind energy as the representative of the renewable energy and new energy, to achieve sustainable development, has become the consensus of the whole society, strategic choice to solve the energy crisis and environmental problems. 2.Overview of control technology of doubly fed wind power gener ation Wind power is the kinetic energy contained in the natural wind into electrical energy in the process, the wind turbine wind energy capture and convert it into mechanical energy, driven by rotary generator, and the generator for converting mechanical energy conversion into electrical energy. As countries around the world pay more attention to wind power, wind power has become the world's fastest, most widely studied and applied new energy technology. With the development of wind power technology, wind turbine, wind turbine generator, converter and its control system and the way of the wind turbine, there are different types of. Among them, the doubly fed wind power generation system due to the converter control capacity is small, the speed of operation range wide characteristics become currently the world's most widely used VSCF wind power generation system. Variable speed constant frequency generator in asynchronous generator rotor side applied three-phase low frequency current to realize AC excitation, the output power is constant frequency and constant voltage amplitude, frequency, phase of the exciting current control. At the same time, the active power and reactive power decoupling control of the generator is realized by using the vector control technology. Control active power capable of adjusting the rotation speed of the wind turbine, to capture the maximum wind power tracking control; regulation of reactive power adjustable power factor and improve the dynamic and static stability of the wind turbine and power system operation. In addition, the VSCF wind power generation technology, so to achieve good flexible connection between the generator and power grid system, compared with the traditional constant speed constant frequency generation system easier to achieve grid connected operation and operation

Chapter 256 - Basic Design of Electric Power Generating System with Wind Energy Generation System for a Large Ship

To ensure minimization of power losses as well as economic feasibility of electrical power generation, economic load dispatch happens to be one of the most challenging optimization problems which is faced in electrical engineering. With the advent of distributed power systems, an interconnection of power systems generating from different sources have come into consideration. However, all sources do not operate in the same manner and hence the generation cost for different sources varies significantly. Economic Load Dispatch (ELD) can be defined as a technique to schedule the power generator outputs with respect to the load demands, and to operate the power system in the most economical way. This paper presents a neural network model for implementing economic load dispatch for a three as well as six generation system. The load is also varied for both the 3 and 6 generations systems. The results clearly indicate that the cost of generation increases with the increase in load, which is also intuitive and hence gets tested. Thus the proposed model can be used to implement an optimized economic load dispatch mechanism for multi-unit power systems which is a typical characteristic of distributed power systems.

A service-oriented architectural (SOA) model is proposed for power system reliability analysis especially for generating capacity adequacy evaluation. Generating system adequacy evaluation is performed to evaluate the ability of the system generating capacity to meet the total system demand. The proposed SOA model is composed of generation system reliability (GSR) service provider, power system service registry and service requester. The data pertaining to power system reliability analysis are represented in extensible markup language (XML) for exchanging the reliability data among the users and service providers. The GSR service provider describes the reliability evaluation services and publishes them to the power system service registry. The calling sequences of reliability evaluation services along with required data are configured as SOAP (Simple Object Access Protocol) messages and the proposed SOA model communicates between the service provider and the service requester with formally defined messages. The proposed model for generating system reliability analysis is highly distributed and has inherent features such as scalability and flexibility and provides a loosely coupled environment for power system reliability analysis.

The reasons to shift the generation system from conventional fuel oil generating system to clean energy sources are now based on the increase of fuel cost, climate change and environmental issues in reducing the greenhouse gas emission and also pollution. Wind is one of the renewable energy that has many advantages and the level of the penetration has increased now. Despite the abundance amount of wind, the fluctuation and the intermittent make wind generation system can affect the reliability of the power system. One of the solutions to the problems above is the use of electrical energy storage system. Power that stored in the electrical energy storage system can be used later when the wind is not strong enough to generate electric power. This research intends to investigate more on li-ion battery as one of the promising means in enhancing the reliability of power system when connecting to wind generation system in order to enhance the power system reliability. This work should contribute significantly in wind energy generation stability improvement with the storage system and there will be an advantage in battery storage system application. The results show the stability improvement of the simulation system connected to the wind generation with the battery.

Solar power is very useful renewable energy, got anywhere. But it is got only in the daytime on sunny days. On the other hand, sometime the grid cannot receive overflowed solar power when electric demand is small. Recently storage battery is utilized in the grid, in the household, combined with solar power generator for accumulating overpowered electricity and emitting it after sunset. It is very useful to utilize solar power effectively and efficiently. It is also useful on the power failure. But we have very little information of technical traits of storage battery, such as energy loss with accumulating and emitting electricity. Building Research Institute in Japan has a demonstration house, which has solar power generator and storage battery combined system. The authors have measured generated solar power, accumulated and emitted overpowered electricity of solar power generation and storage battery combined system for a year. Lots of traits of solar power and storage battery combined system are got. The authors have made modeling and formulation solar power and storage battery combined system, incorporating these traits. In this way, efficiency and effectiveness of solar power generator and storage battery combined system with any generation, storage capacity, can be evaluated with this formulation.

In the context of supplementing energy requirement for remote localities far from the reach of the national grid and having good wind energy potential, installation of modular wind plants operating in the stand-alone mode is the desirable choice. The optimal operation of such isolated generating system is essential so as to increase the overall efficiency and hence reduce the cost of energy generation. Reducing losses also helps to reduce the maintenance needs and increase the longevity of the generating system. Many works relating to the analysis, design and performance optimization of grid connected DOIG based VSCF generation system has been reported in literatures. However, surprisingly little attention has been focused on optimal operation of stand alone DOIG based VSCF generation system. In this paper an optimal operational strategy has been developed for a DIOG based VSCF generation system supplying an isolated load. The constrained optimization problem is solved in the MATLAB environment using the Lagrange multiplier technique. The control algorithm makes the generating system to operate at min. machine loss trajectory while the wind speed, active load power and load power factor angle varies with in their specified range. The theoretical prediction is supported by simulation using MATLAB SIMULINK

A generating system, consistent with its reliability criterion, is capable of serving a firm load for which it is built. In addition to the firm load, the same generating system is capable of supporting a limited amount of interruptible load. This capability is defined as the interruptible load carrying capability (ILCC) of that system. The additional load is served by the resources acquired to serve the firm load, without affecting the reliability of the firm load. The magnitude of ILCC for a given system increases with the reliability of the system, with increased duration of interruption and with the level of reliance that is placed on the emergency operating procedures. The authors present a probabilistic approach used to calculate the ILCC of the Alberta Interconnected System (AIS). These findings helped to determine the maximum level of interruptible load service that Alberta's electric utilities can offer their customers. The impact of various factors on ILCC is discussed and the process is illustrated with numerical results. >

—This article presents an enhanced control strategy for a direct-driven permanent synchronous generator based wind-power generation system with a flywheel energy storage unit. The behaviors of the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit under unbalanced grid fault conditions are investigated. Three control targets for the grid-side converter during network unbalance conditions are identified, including eliminating the oscillations in the total active power or reactive power or no negative-sequence current injecting into the grid. Meanwhile, the DC-link voltage oscillations can be effectively suppressed during the unbalanced grid fault by controlling the flywheel energy storage unit. Furthermore, a proportional–integral-resonant controller is designed for the flywheel motor to eliminate the oscillations in the DC-link voltage. Finally, the proposed coordinated control strategy for the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit has been validated by the simulation results of a 1-MW direct-driven permanent magnet synchronous generator wind power generation system with a flywheel energy storage unit under unbalanced grid fault.

Modeling of the wind and PV hybrid microgrid is carried out by PSCAD/EMTDC. The model includes direct-drive wind power generator, Single-stage photovoltaic power generation system and storage battery. Simulate and analyze the operating characteristics of the microgrid running in grid-connected and islanding mode, which take into account the actual wind speed and light intensity. The simulation results show that the battery is able to regulate the voltage of the point of common coupling and smooth the power fluctuation of wind generator and PV generation system in the grid-connected mode. The microgrid can isolate itself from the grid in a rapid and seamless fashion when the battery adopting P/V and Q/f control strategy based on the droop characteristics.

The contribution of solar power in electric power systems has been increasing rapidly due to its environmentally friendly nature. Photovoltaic (PV) systems contain solar cell panels, power electronic converters, high power switching and often transformers. These components collectively play an important role in shaping the reliability of PV systems. Moreover, the power output of PV systems is variable, so it cannot be controlled as easily as conventional generation due to the unpredictable nature of weather conditions. Therefore, solar power has a different influence on generating system reliability compared to conventional power sources. Recently, different PV system designs have been constructed to maximize the output power of PV systems. These different designs are commonly adopted based on the scale of a PV system. Large-scale grid-connected PV systems are generally connected in a centralized or a string structure. Central and string PV schemes are different in terms of connecting the inverter to PV arrays. Micro-inverter systems are recognized as a third PV system topology. It is therefore important to evaluate the reliability contribution of PV systems under these topologies. This work utilizes a probabilistic technique to develop a power output model for a PV generation system. A reliability model is then developed for a PV integrated power system in order to assess the reliability and energy contribution of the solar system to meet overall system demand. The developed model is applied to a small isolated power unit to evaluate system adequacy and capacity level of a PV system considering the three topologies.

The main aim of this paper is to propose an integrated solar mesh photovoltaic energy generating system (SPV) which includes an SPV, DC-DC boost converter and voltage source converter (VSC), inductors interface, corrugated filter, and three-phase system that would provide various linear and non-linear applications. The currents of the reference grid are forecasted with the power balancing theory to assess the three branches of the voltage source converter (VSC). The hypothesized SPV energy-producing system offers unitary reactive factor and power allowance for voltage control in a three-phase 3φ distribution system. A DC PI voltage regulator governs the VSC's intermediate circuit tension (proportional integral), The maximum power point tracking (MPPT) with an ace in power point is accomplished with the DC-DC boost converter within a two-stage Solar photo voltaic power producing system. The network-connected SPV electrical generation system is designed and analyzed in MATLAB.

Dynamic regulation reliability of a pumped-storage power generating system: Effects of wind power injection

The frequency and duration method has been developed for the evaluation of generating system reliability in the planning of electric power systems. This method makes it possible to determine all major reliability indices: probability and frequency of system deficiency states and the expected energy not supplied to the consumers. For practical applications, simple two-level daily load models have been suggested. The higher load level is taken to match with the estimated daily load peak and the lower level is usually assumed to be equal to mean value for different days. The duration of the higher load level is adopted to be the same for all days but no recommendation has been given as to how to choose it. To investigate the applicability of two-level load models for assessing generation system reliability for planning purposes, a series of comparative analyses of the IEEE Reliability Test System has been performed, applying the exact and various two-level load models. The applicability of two-level models in estimating the absolute and relative system reliability indices is analysed for various generation system structures and load diagram shapes. It has been shown that the two-level load approximation offers a very good estimation of the relative values of all main reliability indices of the prospective generation systems. It has also been established that the two-level diagrams provide fair estimates of the absolute values of the reliability frequency in most cases investigated. This good behaviour of the two-level models has also been found to hold if there are some predictable as well as unpredictable load diagram shape modifications.

In high altitude wind power (HAWP) generating system, medium voltage AC (MV-AC) permanent magnet synchronous generator (PMSG) is used. The generated electrical power is transmitted to ground without any power conditioning in the air-borne unit. The ground based power conversion system (PCS) interfaces variable voltage and variable frequency medium voltage power into distribution level grid voltage. The proposed PCS consists of a three-level vienna rectifier for generation side control, a half bridge DC-DC converter for isolation and step-down purpose and a grid/load connected inverter for load side active power control. Three-level operation in the generation side converter reduces the switch/diode voltage stress to half and therefore allows to use low voltage rating power semiconductor devices. The vienna rectifier is controlled for sensorless maximum power-point tracking (MPPT) of the air-borne wind turbine. The phase lock loop (PLL) is used for speed and rotor position detection of the PMSG for optimal torque control of the airborne wind turbine (AWT). Simulation studies have been carried out using computer programs like PSIM and MATLAB. For the validation of the proposed methodology, scaled down laboratory based prototype is built and tested. The obtained experimental results confirm the performance of the PCS for interfacing HAWP generation system to the grid.