Development Of Flywheel Inverter System For Voltage Sag Mitigation

Power quality is an issue that has been given a continuous attention by the electricity providers and also the consumers. Nowadays, the application of power electronic devices in the industrial sector has rapidly increased. Many of the equipment used in the industries are sensitive to an even small disturbance in power supply such as voltage sag. Voltage sag can cause low quality product, low production quantity and also machine restarting. The voltage sag problem can reduce the profit in long term if it is not given a proper attention.There are many type of solutions that have been developed to mitigate the voltage sag problem. The type of solution that is usually taken by the consumers is by installing energy storage device such as battery, capacitor and motor generator (MG) to inject the power back to the AC system during the voltage sag. In this work, a flywheel is used as the energy storage device. Flywheel has few advantages such as long life cycle, low maintenance work and also cheap. A DC machine has been used with the flywheel in this application. At normal condition, the flywheel stores kinetic energy during the rotation of the machine. The kinetic energy will be transformed to electrical energy when there is a sag in the AC system. In order to deliver the energy to the AC system, the flywheel is used with the static synchronous compensator (STATCOM) system. This system supplies reactive power to compensate the voltage loss during the sag. This work has been divided into two parts which are the simulation and the experiment part. Two types of faults which are balanced phase fault and unbalanced phase fault have been simulated. The balanced phase fault has been created by starting of large induction motor. On the other hand, the unbalanced phase fault has been created by performing a short circuit on the AC supply system. For the experiment part, this sag mitigation system has been tested under the balanced phase fault condition. From both the simulation and experiment results, a good agreement has been obtained. The mitigation system has shown a good ability in mitigating voltage sag problem

Determination of Critical Overload Transmission Line Using Novel Maximum Power Line Stability Index

Recent years, a larger number of DG’s are being employed especially at the critical load ends to reduce the burden on the main feeder. One of the benefits of employing DG that it improves the system voltage stability even with load increment. The primary focus of this paper rests on creating a novel line voltage stability index. The line stability index approach is proposed based on Thevenin theory to gauge the DG level impact on transmission line. Transmission issues due to the overloading of lines in high DG penetration areas during the outage scenarios taking place earlier. The rationale for the proposed strategy will be experimented on a standard IEEE 30 bus test system compared with other line voltage stability indexes

Optimal Placement and Sizing of Distributed Generators Based on a Novel MPSI Index

The Objective: This paper presents a method to identify the optimal location and size of DGs based on the power stability index and particle swarm optimization (PSO) algorithm.Materials and methods: First, a novel maximum power stability index (MPSI) is derived from the well-established theorem of maximum power transfer. The MPSI is utilized as an objective function to determine the optimal DG locations. Next, a PSO-based model with randomized load is developed to optimize DG sizing in view of the system’s real power losses.Results and Conclusion: Lastly, a IEEE 30-bus test system is employed in the simulation. The performance of proposed MPSI index are comparable with other voltage stability indices. The DG optimization model considering voltage stability and loss minimization provides better results compared to that obtained using only loss minimization approach

Widespread compact fluorescent lamp evaluations in 50 Hz electrical network

Rapid development in electrical technology has imposed strong challenges to modern power system. Power quality has become a great concern due to proliferation of power electronic technology in modern electrical loads. Specifically for lighting load such as compact fluorescent lamps (CFLs), one of the concerning issues is harmonics. CFL is a cost-competitive and energy efficient compared to incandescent lamp. Inevitably, CFL produces harmonics current due to nonlinearity behaviour of the electronic ballast circuit. This paper presents a study on the widespread installation of CFL lamps in electrical power network. Initially, the harmonic current characteristics of local-branded CFL was identified from laboratory measurement. Then, a simulated CFL model was developed in MATLAB/Simulink to replicate the identified characteristics. The same step was repeated for other two different brands where eventually all models were embedded into a distribution network. The results show that at low voltage level, with installation more than 50 units for each type of CFL, the harmonic voltage distortion exceeded the 8% total harmonic distortion (THD) limit as stipulated in EN50160 standard. However, at higher voltage, the amount of THD decreased to average 0.94% and further down to average 0.28% at small transmission voltage level

Study of linear-correlation based solar irradiance measurement device photovoltaic application

Solar irradiance is the most fundamental element for energy generation from the photovoltaic system. Huge number of measurement instruments are produced commercially for better reading of this parameter. Nevertheless, there are still no detail studies that have ever been reported regarding the critical relationship between solar irradiance and other electrical parameters such as voltage or current in the literature. This study is essential to determine the correct parameters to be considered in developing a precise measurement of solar irradiance. In this study, a linear-correlation based solar irradiance measurement device has been designed to investigate this relationship. The obtained solar irradiance values from the proposed device exhibit an excellent agreement with those measured by the commercial solar meters/sensors which highly suggest that this study should become a trigger for better improvement of the solar measurement system in the future

Efficient Operation of Lithium-Ion Batteries Based on GPV-Forecasted PV Output

Load forecasting is essential in order to fulfil a demand of the consumer. Nevertheless, for a small-scale Battery Energy Storage System (BESS) based on sole photovoltaic (PV), it needs a very strong effort to always meet a consumer's demand due to unstable meteorological conditions. An ideal PV system requires a constructive control strategy in order to alleviate its fluctuating output. In this study, an energy control scheme that executes next-day forecast of generation for the purpose of fully utilizing the stored energy in the batteries has been proposed. Experimental equipment was structured and the operation was completely administered by RX621 microcontroller. The implemented system worked very well without any distractions and it succeeded in controlling and preventing the batteries from being over-charged or overdischarged. Impressively, average consumption for September 2015 is considerably high, which suggests that the proposed control succeeded in utilizing energy corresponded to 98.6 % of the monthly-average generation

Penempatan dan pensaizan optimum bagi penjana teragih dalam sistem kuasa untuk peningkatan kestabilan voltan

Pada masa kini, kebanyakan sistem kuasa beroperasi dengan muatan beban yang tinggi serta menghampiri had kestabilan voltan disebabkan kekurangan rizab kuasa. Keadaan ini sekiranya berterusan boleh mengakibatkan kawasan yang lemah dalam sistem tersebut menghadapi masalah ketakstabilan voltan. Isu ketakstabilan voltan merupakan salah satu cabaran utama dalam operasi sistem kuasa. Salah satu strategi penyelesaian yang dianggap sesuai untuk meningkatkan kestabilan voltan dan kebolehpercayaan sistem pengagihan adalah dengan menggunakan unit Penjanaan Teragih (PT). Di samping pelbagai manfaat yang dijangkakan dari penggunaan PT, kewujudan sejumlah besar unit PT dalam sistem pengagihan sebaliknya boleh menimbulkan pelbagai masalah dari segi sudut operasi dan ekonomi. Oleh itu, bagi memastikan manfaat yang maksimum boleh diperolehi dari kehadiran sejumlah besar PT dalam sistem pengagihan, penentuan penempatan dan saiz unit PT secara optimum perlu dilakukan. Fokus tesis mi adalah untuk membangunkan satu formulasi pengoptimuman yang barn untuk menyelesaikan masalah penempatan dan pensaizan optimum PT dengan menimbang fungsi berbilang objektif untuk menyasarkan peningkatan kestabilan voltan, pengurangan kehilangan kuasa dan pengurangan kos PT. Satu indeks kestabilan voltan barn yang dinamakan Indeks Kestabilan Kuasa Maksimum (IKKM) telah dibangunkan untuk mengenal pasti bas sensitif dalam sistem kuasa yang mudah terdedah kepada keruntuhan voltan. Pengolahan indeks IKKM dibuat bersandarkan kepada gabungan konsep pemindahan kuasa maksimum dan teori kestabilan sistem dua bas. Bagi menyelesaikan masalah pengoptimuman pula, Algoritma Carian Jejak-balik (ACJ) yang merupakan satu teknik pengoptimuman heuristik yang agak barn telah diguna pakai dalam kajian. Pengesahan keseluruhan ACJ yang dicadangkan telah dilakukan ke atas dua sistem ujian, iaitu, IEEE 30-bas dan sistem pengagihan 69-bas. Selain itu, keberkesanan teknik pengoptimuman mi juga telah dibandingkan dengan teknik pengoptimuman heuristik yang lain seperti Pengoptimuman Kerumun Zarah (PKZ) dan Algoritma Genetik (AG). flasil kajian menunjukkan bahawa indeks IKKM yang dicadangkan dapat mengenal pasti dengan tepat bas beban yang terdedah kepada keruntuhan voltan. Keputusan menunjukkan peningkatan tahap kestabilan voltan yang memuaskan telah dicapai melalui penempatan PT yang optimum. Manakala dalam penentuan kapasiti PT, cadangan model pengoptimuman yang memberi penekanan terhadap kedua-dua manfaat teknikal dan ekonomi telah menunjukkan prestasi sistem yang terbaik dan aspek kehilangan kuasa serta kos pelaburan PT yang optimum. Selain itu, hasil keputusan menunjukkan bahawa pengoptimuman menggunakan ACJ memberikan prestasi terbaik berbanding dengan PKZ dan AG dari segi masa pengkomputeran dan kadar kejayaan dalam mencapai penumpuan sejagat

EFFECT of DG Optimizing on overload Transmission line Stability

Typical steady state studies always treat the peak power demands as the worst case conditions. Periods of light load are also critical in the assessment of the possible state of a power system. While heavy load conditions are generally associated with overload, low voltage and generation deficiency, light load conditions may give rise to over-voltage and undesirable reactive power requirements at generation side. This paper focus on study the effect of DG Optimizing on overload Transmission line Stability. The system dispatch constraints should be taken into account to compensate or varying DG generation output and to enhance the operational performance of power systems. This dispatching operation depends on the change of DG generation and the dispatching strategy. The impact of DG generation uncertainty is limited with the generation dispatching operation and should not be neglected in system analysis

A Sizing Tool for PV Standalone System

This project aims to develop a software for sizing a standalone photovoltaic (PV) systems. The proposed tool has the capability to allow the user to employ meteorological data such as ambient temperature, irradiation data, and peak sun hour (PSH) in designing the PV system. Usually, a micropower system is designed to serve a specific load demand, in this work, the stand alone PV is modelled with a particular load profile to ensure that the system meets required energy demand. The developed tool is used to determine the feasibility of the stand-alone system in terms of PV size and the estimated total power production. The tool developed with a built in database which stores different types of PV panels, batteries, charge controllers and inverters. The proposed sizing tool was validated based on the real data implemented on the case study for a residential buildings

A Risk Assessment of Transmission Line Overload Based on MLSI/PSO

Aiming at the randomness of the output power of distributed generation, a method of transmission line overload risk assessment based on MLSI/PSO is proposed. Based on the traditional partial swarm optimization algorithm, the corresponding weights are selected according to the influence factors of each input quantity, and the calculation accuracy of the traditional point estimation method is improved to realize the overload risk assessment of transmission lines. The risk of transmission line overload in IEEE30 bus system with wind-solar complementary generation unit is evaluated. The analysis results show that the proposed method has the characteristics of low calculation cost and high prediction accuracy compared with traditional point estimation method