Prabath J. Binduhewa

Extraction of parameters for simulating photovoltaic panels

Presented in this paper is a method of simulating photovoltaic modules by taking the manufacturer specified data at standard test conditions as inputs. A method for estimating unknown parameters of a simplified version of the single diode solar cell model corresponding to a given photovoltaic panel is described. In the proposed approach, the equivalent circuit represents an entire solar panel, composed of several solar cells. A new method, which is simple, is also proposed to identify the ideality factor of the equivalent diode along with the series resistance. Estimated unknowns are used in generating module output curves at different environmental conditions. The generated curves are compared with manufacturers data. The curves are also compared with curves generated with an alternative method available in the literature. The superiority of the proposed technique is demonstrated.

Uninterruptible power supply for short-time power back-up using ultracapacitors

This paper presents an uninterruptible power supply capable of proving power for several seconds. Ultracapacitors are used as the storage method since they are suitable for pulse power applications and longer life time. Selection of ultracapacitors and controller design for associated power electronic converters are presented in this paper. Further simulation results of the proposed uninterruptible power supply are also included in the paper.

Investigation of a smart transformer

A method for demand side voltage control, using a three winding smart transformer is investigated. The concept is to control the secondary side voltage of the transformer by injecting a voltage to the tertiary winding. This paper presents a design methodology for the proposed transformer, as well as for the controlling scheme, and validates the concept through simulation and hardware implementation. Also an analysis of the operational efficiency has been presented. Then, the limitations of the design and the possible improvements in developing the prototype model as a final product has been discussed.

Dynamic Stiffness-Based Control for a MicroGrid Microsource Interface

Intermittent renewable microsources in so-called MicroGrids will need to have plug-and-play functionality, therefore, will need to be integrated with local storage. The design of such cross-coupled nonlinear systems is complex and presently focuses on command tracking dynamics. In practice, the robustness of such systems to external disturbance inputs plays at least an equal role. This paper presents the dynamic stiffness methodology for such design and illustrates it for a single-phase photovoltaic microsource with battery energy storage. While this method has been applied with considerable success in motor drives (converter plus single load) and uninterruptible power systems (converter plus energy storage), it has not so far been applied to the more complex case considered here of a microsource with embedded storage (converter plus energy source plus storage). The mathematical model of the system is derived and presented in state feedback block diagrams whereby local and global external disturbances and cross-coupling are clearly identified. The resulting system is clearly able to prevent the propagation of external disturbances from one end to the other. Experimental results are provided to validate the operation of the proposed controller.

Investigation the feasibility of distribution system voltage regulation with a three winding transformer

It is anticipated that with increased penetration of micro scale renewable generation sources, electric vehicles and demand response initiatives the voltage of low voltage networks need to be controlled in real time. Commonly used method of voltage control is on-load tap changing. However as this has limitations, an electronically controlled Volt-Var Control (VVC) scheme based on a three winding transformer is investigated. Two configurations based on serial injection and parallel compensation are studied for their relevant merits. A simple radial network with two loads was considered to assess the effectiveness of the proposed WC schemes against a tap changing transformer. WC approaches presented in this paper seem to be promising. However, further work is required with a more realistic transformer and a power electronically controlled voltage source converter to assess the effectiveness of this scheme.

Alternative operation methods to reduce the energy demand of a traffic light controlled pedestrian crossing

Traffic light controlled pedestrian crossings are implemented to ensure the safety of pedestrians. This paper presents two methods to reduce the energy consumption of a traffic light system implemented to control the pedestrian crossing. Energy saving is gained by means of new operating sequences for the traffic lamps. Analytical results are presented to compare the energy saving achieved with alternative methods, when compared with standard operating method. Energy storage capacity reduction, when the traffic light system is powered by a photovoltaic panel, is also presented.

Design and implementation of a control strategy for a transformer with series compensation

With the increasing levels of distributed generation, the control of voltages within statutory limits across distribution networks becomes challenging. Further, the demand depends on the load busbar voltages to some extent and therefore the voltage control becomes an important means of load control especially at peak load periods. An electronically controlled series compensator based on a three winding transformer was investigated to control the distribution network voltages The controller design and operation of the three-phase series compensator and its control are discussed. The proposed topology and control strategies are evaluated for specific transformer loading condition using simulations.

Low cost torque estimator for DC servo motors

Electromagnetic torque of a DC motor can be measured directly by a torque sensor attached to the shaft. However, this is an expensive solution requiring additional power, interfacing and sometimes such a torque sensor can be too bulky to be implemented in a compact environment. Alternatively, the armature current measurement can be used to derive the electromagnetic torque of the DC motor, provided the motor torque constant is known and does not vary over the time. In addition, this method also needs an additional current sensor and its integration circuits. However, in general, DC servo motors are equipped with either absolute or incremental encoder connected to the shaft. This can be used to estimate the torque without any additional sensor.

Load flow analysis of low voltage dc networks with photovoltaic

Even though the power systems for the last century have been running on ac, with the emerging dc technologies such as solar photovoltaic (PV), LED lights, electric vehicles (EVs) and so on the interest for dc networks are also increasing. Rather than the traditional practice of inverting the dc power output of PVs to ac, it would be efficient if the dc power is used without inverting. With the development of the low voltage dc (LVdc) networks, it is essential to develop tools to analyze these networks. In this paper, a load flow program was developed to analyze LVdc networks that incorporate PV generation modules. The PV modules were modeled with its dc/dc converter in Simulink. The load flow study has been carried out on LVdc network using three different methods and the results were compared.

Design and Implementation of a Novel Controller for Autonomous 2.5 kW Wind Power Plant

Increase of electricity demand force the electrical engineers to come up with new solutions. Renewable energy sources, which needs lesser maintenance cost and with lesser environmental effects are gathering momentum. Wind power, major renewable energy source has great potential through out the world. Developing country as Sri Lanka is very much interested in wind power generation and putting effort to implement even for lower capacity. A new control was designed and implemented on 2.5 kW wind power plant is presented in this paper. The system was simulated and the results are validated with the laboratory setup before field implementation takes place