International Journal of Engineering Science and Computing, January 2017 4156 http://ijesc.org/ ISSN 2321 3361 © 2017 IJESC Power Quality Improvement by Custom Power Devices- A Review Pradeep Kumar 1 , Dr. Ritula Thakur 2 , Dr.Lini Mathew 3 M.E Student 1 , Assistant Professor 2 , Associate Professor and Head 3 Department of Electrical Engineering, National Institute of Technical Teachers’ Training and Research, Chandigarh, India Abstract: Power quality is one of major concerns in the present era due to the increase in modern sensitive and sophisticated loads connected to the Distribution System. Recently, the Power electronics controllers are gaining concern to provide the quality of power for both power suppliers and consumers. Many power filtering technology i.e. passive filters, active power filters, hybrid filters have applied from time to time for giving the solution of power quality problems to end users, but the users could not fully satisfied them. New technologies, using power electronics-based concepts, have been developed to provide protection for commercial and industrial customers from power quality problems on the electrical distribution system. Such power electronics based devices are known as Custom Power devices. There are many custom power devices and they are divided in two groups: network-reconfiguring type and compensating type. The network reconfiguring devices are: solid-state current limiter (SSCL), solid-state breaker (SSB) and solid-state transfer switch (SSTS). The compensating devices are: Distribution Static Compensator (DSTATCOM), Dynamic Voltage Restorer (DVR), and Unified Power Quality Compensator (UPQC). This paper present an overview of custom power devices used in the distribution systems for mitigating the power quality issues. Ke ywor ds : Custom power, Distribution Static Compensator (DSTATCOM), Dynamic Voltage Restorer (DVR), Unified Power Quality Compensator (UPQC). I. INTRODUCTION In many ac distribution systems, due to installation of sensitive and sophisticated sensitive nature of loads, users continue to demand higher power quality. There are numerous power quality polluting loads are present in a power system. New technologies, using power electronics-based concepts, have been developed to provide protection for commercial and industrial consumers from power quality problems on the electrical distribution system. Such power electronics based devices are known as Custom Power devices. The custom power devices are installed in a distribution networks for mitigating the various power quality problems. The custom power enhances the reliability and quality of power that is delivered to customers. Custom power provides an integrated solution to these problems which are faced by the utilities and power distributors. The custom power devices are basically of two types – network reconfiguring type and compensating type. The network reconfiguring devices are: solid-state current limiter (SSCL), solid-state breaker (SSB) and solid- state transfer switch (SSTS). The compensating devices are: Distribution Static Compensator (DSTATCOM), Dynamic Voltage Restorer (DVR), and Unified Po wer Quality Compensator (UPQC). II. CUS TOM POWER CONCEPT Custom Power is a concept based on the use of power electronic controllers in the distribution system to supply value-added, reliable, high quality power to its customers. For many customers this is a preferred alternative to the customer improvising utility power by their own means, mostly in a band aid manner with numerous uninterruptible power supplies, as is done now. There are many utilities are moving in the direction of value-added Custom Power service to their end users (large customers). Custom Power means that the customer receives quality power with specified standards from a utility or a service provider. The equipments installed by the end users in coordination with the utility, which includes an acceptable combination of the following features:  No (or rare) power interruptions.  Magnitude and duration of voltage reductions within specified limits.  Magnitude and duration of overvoltages within specified limits.  Low harmonic voltage.  Low phase unbalance.  Acceptance of fluctuating, nonlinear and low power factor loads without significant effect on the terminal voltage. This can be done on the basis of an individual, large customer, industrial / Commercial Park or a supply for a high tech community on a wide area basis. III. CUS TOM POWER DEVICES Custom power is a strategy, which is intended principally to convene the requirement of industrial and commercial consumers. Figure. 1. Classification of custom power devices. Research Article Volume 7 Issue No. 1