**9. Acknowledgment**

The excellent collaboration that my colleagues and I have with the InTech editors was an experience and an honor for the professional manner in which they coordinated the accomplishment of this book.

Dorin Sarchiz

110 Electrical Generation and Distribution Systems and Power Quality Disturbances

The button MAINTENANCE ESTIMATION comand, presented in Figure 17, opens the interface for planning preventive maintenance for OEL or for its components, for a determined period and in the required technical and economic conditions, presented in

The influence of the number of renewals *r* [pieces], calculated on the OEL or on its components, allows a study of renewals influence on the reliability at the end of the period

Do to its complexity, the developed program, which was conducted on the basis of theoretical considerations presented in previous sections, allows a much easier assessment of the reliability of the studied system and allows an optimization in planning PM, in

The paper is the result of basic research in the field of operational research and maintenance management, with contributions and applications in optimization strategies of RCM for EDS. The contributions refer to the formulation the mathematical models of preventive maintenance strategies belonging to RCM, solving technical and economic objectives of the

The optimal solutions to these models, with applications on a OEL 20KV as an EDS subsystem, allow a fundamental planning of RCM, through: setting the optimal number of future actions for the preventive maintenance PM, on overhead electric line or its

**7.4 Preventive maintenance planning** 

of study, presented in Figure 22.

Fig. 22. Influence of the number of renewals

different technical and/or economic situations.

exploitation distribution systems and systems use electrical energy.

**8. Conclusions** 

Fig. 21. Interface for planning PM on the OEL or its components

Figure 21.

"Petru Maior" University of Targu Mures, Romania

#### **10. References**


**5** 

*India* 

**Power Quality Improvement by Using** 

**of Grid Side Converter** 

*MIC College of Technology, NIT Rourkela* 

Vasanth Reddy Bathula and Chitti Babu B.

**Synchronous Virtual Grid Flux Oriented Control** 

The conventional energy sources are limited and have pollution to environment as more attention and interest have been paid on the utilization of renewable energy sources such as wind energy, fuel cells and solar energy. Distributed power generation system (DPGS) is alternative source of energy to meet rapidly increase energy consumption. These DPGS are not suitable to be connected directly to the main utility grid. Rapid development of power electronic devices and technology, double sided converters are used to interface between DPGS and utility grid as they match the characteristics of the DPGS and the requirements of the grid connections. Power electronics improves the performance of DGPS and increase the

Rapidly increase in number of DGPS's leads to complexity in control while integration to grid. As a result requirements of grid connected converters become stricter and stricter to meet very high power quality standards like unity power factor, less harmonic distortion, voltage and frequency control, active and reactive power control, fast response during transients and dynamics in the grid. Hence the control strategies applied to DGPS become

In this chapter, a virtual grid flux oriented vector control [2] (outer loop controller) and three different types of current controllers such as hysteresis current controller, current regulated delta modulator, modified ramp type current controller (inner current loop) techniques are proposed, with main focus on DC link voltage control, harmonic distortion, constant switching frequency, unity power factor operation of inverter. Vector control of grid connected inverter is similar to vector control of electric machine. Vector control uses decoupling control of active and reactive power. The control system for the vector control of grid connected converter consists of two control loops. The inner control loop controls the active and reactive grid current components. The outer control loop determines the active current reference by controlling the direct voltage. A cascaded control system, such as vector control is a form of state feedback. One important advantage of state feedback is that the inner control loop can be made very fast. For vector control, current control is the inner control loop. The fast inner current control nearly eliminates the influence from parameter variations, cross coupling, disturbances and minor non-linearity in the control process. Vector control uses PI-controllers in order to improve dynamic response and to reduce the

power system control capabilities, power quality issues, system stability [1].

of high interest and need to further investigated and developed [3].

**1. Introduction** 

*Conference on Power Systems MPS 2010.,* Acta Electrotehnica Journal, Academy of Techinal Sciences of Romania, Technical University of Cluj-Napoca, Vol. 51, No. 5, 2010, Mediamira Science Publisher, pp.134-137, ISSN 1841-3323


http://www.cired2010-workshop.org/pages/012/title/Home.en.php

