INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 3, ISSUE 5, MAY 2014 ISSN 2277-8616 309 IJSTR©2014 www.ijstr.org Power Supply Quality Improvement With An Extended Range Domestic Voltage Requlators Ayodele Sunday. Oluwole, Temitope. Adefarati, Kehinde. Olususyi, Adedayo Kayode. Babarinde Abstract: One of the effects of the rapid expansion of distribution networks in Nigeria is that the service voltage of many consumers lies outside the stipulated tolerance. This problem has been addressed by the use of commercial, domestic voltage regulators that typically work between 150 and 250 V. Unfortunately the service voltage experienced by many consumers lie well outside this range. In order to establish the operating range of suitable regulators, a preliminary study of the voltage supply in Ondo State, Akure as a case study, the distribution network was carried out. It revealed that up to 30 of consumers receive voltages of less than 80V whilst up to 50 receive less than 120V. In the light of this, it was decided to design a suitable voltage regulator rated at 1.5KVA having an input voltage range between 50V and 250V with an expected nominal output voltage of 220V 6 .A theoretical framework was developed for the general class of switched electronic AC Voltage regulators using EXCEL ® . It provides a mechanism for computing the number and ratings of tapping needed to regulator transformers once the output voltage tolerance is specified. Index Terms: Distribution Network, regulator, transformer, tapping, voltage tolerance. ———————————————————— 1 INTRODUCTION THE problems encountered by consumers in the Nigerian power supply system are numerous. However, a major problem is the quality of power supplied. The availability of adequate supplies of electricity at the nominal level of 220 volts for domestic purposes is a matter of great concern throughout Nigeria. In the pre – oil boom era the quality of power as characterized by the supply voltage closely matched the nominal values. However the boom led to a phenomenal growth of demand in power which was met by crash supplies of expansion of the distribution lines often times without the commensurate upgrading of the supply transformers. In some cases larger transformers were installed to feed loads located further and further away from the sub – station (Olufeagba, 2006). The net result of this is that consumers in different parts of an area receive voltages far removed from the nominal values. Consequently a burgeoning market for automatic stabilizers and regulators rated between 0.5 KVA and 10 KVA for the domestic market has grown. The devices have various advertised performance limitations and employ a combination of electronics to select the tappings on transformers. In an ideal situation, voltages no less than 170 volts can be readily taken care of with outputs lying within the stipulated tolerance of the supply authority’s values. Unfortunately, the unrestricted expansion of the distribution networks has led to extremely low voltages so that the typical commercially available voltage regulators are not effective for restoring some sort of acceptable operating voltage. A preliminary study carried out during this research and reported below, reveals that the situation in practice is much worse with consumer voltages as low as 50 volts being quite possible (Olufeagba, 2006). Statistical data reveal that 22% of stabilizers purchased by consumers did not perform satisfactorily when the input supply voltage was less than 160 volts. Products like Qlinks, Binatone, Philips, Super Masters, Century etc, regulate input voltage that falls within 160 volts and 260 volts, a range that does not cater for the Nigerian buyer (Ogunlade, 1999). 2.1. The Objectives of the Research The objectives of this research are as follows: i. To determine the range of the voltages supplied to consumers in the electric power distribution network; ii. To design a suitable voltage regulator rated at 1.5 KVA with the output voltage of 220±6% volts, when the input voltage varying between 50 volts and 250 volts. iii. To evaluate the performance of the designed voltage regulator. 2.2 Scope of the Research The supply voltage experienced by the consumers in the Akure network was monitored at several parts of the network and the range of values established. The experience of users of commercial voltage regulators was assessed and confirmed theoretically. The parameters of voltage regulators that can improve the quality of service were then determined. A procedure for the design of the control transformer in a.c. Voltage regulators using a generic formula to determine the toppings were simulated and verified using EXCEL ® software. The decision circuit of the regulator was designed using an iterated logic technique. 2.3. Research Methodology. The design of the regulatory system depends mainly on the power requirements, the input voltage range, the nominal output voltage and regulation. These requirements need to be translated into design specifications for the output element which in this case is a multi-tapped transformer. The method employed in this research is based on tap-changing of a special regulator transformer. 3. The Automatic Voltage Regulator (AVR) The ideal automatic voltage regulator is a device which uses a switched autotransformer to maintain an AC output that is as close to the standard or normal mains voltage as possible, under conditions of fluctuation (Boylestad, 2007). It uses a servomotor (or negative feedback) to control the position of the tap (or wiper) of the autotransformer. An increase in the mains voltage causes the output to increase, which in turn causes the tap (or wiper) to move in the direction that reduces the output towards the nominal voltage (Patchet, 1954). With the exception of passive shunt regulators, all modern electronic voltage regulators operate by comparing the actual output voltage to some internal fixed reference voltage. Any difference is amplified and used to control the regulation element in such a way as to reduce the voltage error. This forms a negative feedback servo control loop; increasing the open-loop gain tends to increase regulation accuracy, but