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This paper has focused on power quality investigation based on complex measurements in the substations of local distribution networks. The distribution network area chosen for the present analysis is of interest for a further renewable sources connection. For the power quality assessment a new type of information report is discussed as viable future alternative for network operator. According to this,...
Power quality is one of the most discuss topics in power industry. There are numerous types of power quality issues but voltage sags and harmonics are a major concern to the customers. Generally, voltage sags are short duration reductions in rms voltage caused by faults in the electric supply system and starting of large loads. Many industrial customers using sensitive equipments suffer a huge loss...
The necessity for clean electric power without any power quality problems has persuaded distribution companies to overcome these issues. Sag/swell, flicker and harmonics are these ones. Among them, voltage sag is one of the most important problems. This phenomenon imposes a bad effect on domestic and industrial loads, especially on sensitive ones. An alternative is use of distributed generation (DG)...
The Dynamic Voltage Restorer (DVR) is an equipment works based on power electronic devices which has been applied to protect the sensitive loads against voltage disturbance. This equipment is one of the instruments in Custom Power Park (CPP) which uses Distributed Generation (DG) source connected to DC bus to compensate the voltage sag of sensitive loads. Combined operation of DVR with DG unit connected...
Power quality has become an important factor in power systems, for consumer and household appliances with proliferation of various electric/ electronic equipment and computer systems. The main causes of a poor power quality are harmonic currents, poor power factor, supply voltage variations, etc. In recent years the demand for the quality of electric power has been increased rapidly. Power quality...
This paper describes the application of the smart medium to low voltage transformer to increase the flexibility of distribution networks, support the accommodation of distributed generation and to attenuate the voltage fluctuations originating from medium voltage network. The theoretical framework is set and three possible control strategies are investigated and their performance to mitigate voltage...
Voltage sag is one of the major power quality problem which results in a failure or a mis-operation of end use equipments. Sensitive industrial loads and Utility distribution networks all suffer from various types of outages and service interruptions which can cost significant financial loss per incident. The aim therefore, is to recommend measures that can improve voltage sag. In this paper a method...
Since Microgrid located downstream in distribution network, voltage sags caused by short circuit have become common power quality events that users of Microgrid have to face. According to where the short circuits occurred, voltage sags can be divided into two categories, interior voltage sag and exterior voltage sag. Exterior voltage sag caused by short circuit taking place in distribution network,...
The paper describes the process of revision of European Standard EN 50160 on voltage characteristics of electricity supplied by public distribution networks, with a consequent evaluation of the Italian situation. The revision was initiated after the decision of the Council of European Energy Regulators (CEER) to participate to the standardization activities collaborating with the European Committee...
Recently, Dynamic Voltage Restorer (DVR) has become a popular power electronic device as a protection for sensitive loads from voltage sag. Voltage sag widely known as one of the major problem in power quality, it is defined as a short reduction of voltage from the nominal. DVR is a custom power device for voltage sag mitigation which works when the fault occurs in power distribution system. In this...
Most of the dispersed generation systems (DGS) have smaller installation capacity and have to be connected to the distribution network to supply electric power into the utility as well as local loads. When the DG is interconnected in parallel with the utility distribution system, some operating conflicts might arise that affect the system power quality. This paper investigate the effect of DG on the...
Nowadays, many electrical systems are practically sensitive to short power disturbances and voltage sags. Since three decades ago, many research of superconducting magnetic energy storage (SMES) system have been doing to improve power quality of sensitive electric systems. The objective of this paper is to present the modeling and analysis of a SMES to protect a sensitive load in Azarbayjan distribution...
The problem of voltage sags and Swells and its severe impact on sensitive loads is well known. To solve this problem, custom power devices are used. One of those devices is the Dynamic Voltage Restorer (DVR), which is one of the most efficient and effective modern custom power devices used in power distribution networks. This paper described DVR principles and voltage correction methods for balanced...
A Unified Power Quality Conditioner (UPQC), which integrates shunt and series active filters, is a powerful tool to settle the power quality problems. In this paper analysis results of a combination the UPQC with the superconducting magnetic energy storage (SMES) are presented. The proposed scheme can compensate voltage sag, voltage interruption and harmonics at the point of common coupling (PCC)...
With the development of information and automation techniques, dynamic voltage problems are once again in the spotlight. Dynamic voltage restorer (DVR) is a modern and important custom power device used for mitigating voltage sags in power distribution systems. The operating principles, structures, and control strategies of DVR are surveyed and compared in the paper after investigating a large amount...
Recent improvements and advances in power electronic technology offer potential solutions to several technical and economical problems associated with distribution networks. In particular, dispersed generation (DG) units that use this technology can provide both energy and ancillary services. In this paper, a selected number of DG units (in particular, fuel cells and photovoltaic cell-based systems),...
This is a companion paper to a paper of the same title, Part I. In the Part I paper, it was proposed that a centralized control system be established to coordinate some selected dispersed generators (DGs) in a distribution system for providing the usual energy service as well as some ancillary services, such as reactive power control, load following, and compensation of continuous PQ disturbances...
Distributed generation (DG) has impacts on the performance of connected distribution network. DG is usually not requested to participate in voltage regulation of the distribution network and will be disconnected from the distribution network quickly enough when a fault occurs in it for eliminating DG's negative influence. But in this way it will also limit the capability of DG to suppress the voltage...
Improvement of the power quality in the utility grid can be obtained by connecting damping power-electronic devices. Regarding the increased presence of converter-based distributed generation units in the power system, an active front end for distributed generation units is extended with a mitigating function. The effects of this mitigating function on harmonic voltage distortion and voltage dips...
In recent years, power system has employed many applications of power electronics technologies for power quality improvement. Unified Power Quality Conditioner (UPQC), which consists of double converters connected by a DC capacitor with each other, has great potential because of its high controllability. Various attractive applications for power quality improvement are considered but the active power...
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