The Voltage Sag Problems and Solutions - Report Example

THE VOLTAGE SAG PROBLEMS AND SOLUTIONS Name: Course: Instructor: Institution: City: Date: Abstract In the recent years, several industrial facilities have had to grapple with issues of service reliability and the quality of power within their premises. This has been greatly attributed to the ever increasing automation and sensitivity of electronic equipment. Despite the fact that quite a number of utilities put more efforts into ensuring that there is reliability and improved quality in power supply, issues of frequent voltage sags have become so rampant. This explains why it is utterly important for any electronic equipment to be protected from such interruptions as voltage sags and power surges (Bollen, 2000). Table of Contents Abstract 2 Introduction 4 Research Problem and Research Outcomes Specification 4 Literature Review 6 Voltage Sag Explained 6 Causes of Voltage Sag 7 Solutions to Voltage Sag 7 Research Methodology and Planning 8 Research Framework 9 Research Approach 9 Research Design 10 Research Strategy 11 Research Philosophy 12 Data Analysis 12 Justification of Preliminary Research Findings 13 Conclusion 14 References 14 Introduction For any electronic device, it is a requirement that the electricity supply is such that its voltage remains within a range that is not only consistent, but one that is also safe for the said device. There have been so many confusions between voltage sags and power interruptions in so far as the safety of electronic devices is concerned, with many people finding it difficult to distinguish between the two. The truth, however, is that voltage sag is just part of power interruptions. Specifically, therefore, voltage sag may be defined as a very brief scenario when the magnitude of the Root-Mean-Square (RMS) voltage drastically falls. According to Math & Bollen (2000), typical voltage sag takes virtually less than one minute to occur, and they are usually brought about by such phenomena as falling trees, lightening, or merely a fault in the electronic equipment. Whereas voltage sag causes a drastic reduction in the effective voltage in a system, interruptions are mainly fatal in the sense that they lead to a total absence of voltage in the system (Math & Bollen, 2000). This paper, therefore, seeks to provide some in-depth research in the problem of voltage sag. It involves a discussion on what the previous researchers have presented on this matter in terms of the actual causes, effects, and solutions to voltage sag problems. Research Problem and Research Outcomes Specification Owing to the current technological advancements especially in issues to do with power and its interruptions, so many problems have occurred due to voltage sags in electronic devices and distribution systems at large. Such problems have led to significant losses to the consumers of power, and to the extreme, deaths have also had to occur (Bollen, 2000). In view of this reality, the consumers of power, producers and suppliers of power, as well as research institutions have been on a journey of trying to understand the causes of voltage sag with a view to reducing its occurrence in the system. Despite these attempts, not so much information is available especially to the users on the basics about voltage sag. Ironically, however, these are usually the most affected whenever voltage sag occurs in electronic equipment and the distribution system as well. In fact, for the longest time now, users and other stakeholders have always taken issues of voltage sag for granted not knowing that even though it signifies a small reduction in the effective voltage, its consequences can be dire at times. Unless enough knowledge is provided out there in matters voltage sag and its problems, it may be very difficult for users to evade some of these dire consequences that come with voltage sag. The users of power have every right to obtain a scientific platform of the voltage sag problem as well as to acquire scientific analysis of the many instances of voltage sag. Through such information, these users are likely to make informed decisions on what exactly to expect in case voltage sag occurs under their watch. This information is also significant in helping the users to note and understand the various causes of voltage sag with the aim of attempting to manage voltage sag events when they occur within their jurisdictions. Two main factors are significant in determining whether indeed the impact created by voltage sag occurrence is intense or not. These are strength and time-frame within which the sag occurs, and the sensitivity of the equipment being used. Some of the electronic instruments that are quite susceptible to voltage sag include motor starter contactor; PLCs, control relays, and speed drive controls (Math & Bollen, 2000). Unfortunately, this information is particularly not with the very end users of most of this equipment. This, therefore, necessitates the implementation of such a research as this particular one so that not only users of this power may be aware, but also the power producers and suppliers alike. At the end of this research, therefore, certain specific outcomes are expected. They serve as the hypotheses for the research. First, it is expected that the findings will point to the fact that voltage sag is brought about by three main causes i.e. faults in the transmission line, starting of the induction motors, and the energizing of the transformer. The second hypothesis for the research is that some of the solutions to voltage sag problems include the use of electrical and electronics equipment whose tolerance is slightly higher to cushion them from voltage sags, implementing the use of coil hold-in devices mainly to counter the effect of voltage sags on contactors and individual relays, adjusting the power being supplied to the equipment in question, and setting up power conditioning devices (Bollen, 2000). Literature Review Voltage Sag Explained Voltage sag is not necessarily a total lack of power, but a temporary fall in the effective voltage in electronic equipment or the power supply and distribution system that typically occurs usually in a period of less than one minute (Dugan, Mark, Surya, & Wayne, 2003). It has always been the desire of most utilities to ensure a secure and reliable electric power within their premises. Their desire, however, has always been thwarted by voltage sag is attributed to very many causes that keep varying always. This has been a challenge in the sense that even when users prevent their utilities from a certain cause(s) of voltage sag, there are still other causes that will remain unmitigated at all times which continues to leave them vulnerable (Sankaran, 2002). Causes of Voltage Sag Of the many cause of voltage sag, storms have been reported as the most prevalent causative agent of voltage sag especially in external environments. According to Dugan, Mark, Surya, & Wayne (2003), when a storm occurs, it leads to several instances of variations in the supply of power to different users. In the course of this, voltage sags also have a higher likelihood of occurring. System faults are also a major cause of voltage sag. According to Math & Bollen (2000), when faults occur, the operations of a power plant and other industrial utilities are interfered with in one way or another. The extent of damage, however, largely depends on whether the fault is symmetrical or asymmetrical. For a symmetrical fault, the strengths of the resultant voltage sags are of equal magnitude in each phase, while for asymmetrical faults, the resultant voltage sags have magnitudes that are not equal (Dugan, Mark, Surya, & Wayne, 2003). System faults that may lead to voltage sags are such that their magnitudes are largely affected by such factors as the impedance of the fault, the pre-sag voltage level, the manner in which the system is configured, and the type of fault (Bollen, 2000). Starting of induction motors is also a source of voltage sags. It is indeed a known fact that induction motors are usually balanced at 3 loads (Dugan, Mark, Surya, & Wayne, 2003). This, therefore, makes the voltage sag arising from their starting to be symmetrical in nature. Solutions to Voltage Sag The solutions to voltage sag especially in electronic equipment are mainly founded on the knowledge and understanding of how sensitive equipment is to power interruptions and voltage sags alike (Le, Lamoree, & McGranaghan, 1994). According to Dugan, Mark, Surya, & Wayne (2003), one way of solving voltage sag and its impact thereof is by installing controls and also using equipment whose tolerance to voltage sag is high. In most cases, such information is usually available on the equipment being bought. This is more of a precautionary measure than a solution. Voltage sag especially on individual relays and contactors may also be solved by installing devices known as coil hold-in (Le, Lamoree, & McGranaghan, 1994). They go a long way in helping to reduce the adverse effects of voltage sag in these particular equipment. Other miscellaneous ways of solving the problems of voltage sag involve installing power conditioning devices (Dugan, Mark, Surya, & Wayne, 2003). For AC power supply, an Uninterruptible Power Supply (UPS) may be used though with some caution since UPS is dependent on the limited battery life besides emitting hydrogen gas which is harmful. Constant Voltage Transformer (CVT) is also useful in helping to regulate voltage so as to reduce the adverse effects of voltage sag (Le, Lamoree, & McGranaghan, 1994). Research Methodology and Planning The methodology adopted to collect the data and information for this research in order to answer the research question and explain the objectives include both qualitative and quantitative approaches. It will involve collection of data and information from the database of several electrical and electronic magazines that provides a discussion on the voltage sag problem and the proposed solutions. Moreover, it will also incorporate designing questionnaire for a public survey of the power users in order to grasp their views regarding their experiences with voltage sag problems and how they can tackle it. Research Framework The research will be based on a research framework that deduces and induces as termed by the model of Ragain (Jeucken, 2004). According to Ibid (2001), the process of deduction is based on the process of achieving a specific result from the general theories and ideas. In this case, the theories and approaches will revolve around the common beliefs surrounding voltage sag problems and its possible solutions. Research Approach Qualitative Method: This approach determines the perspective of the groups or individuals associated to the research question – power utilities, in this case. It will involve the emerging questions on voltage sag problems, data analysis induced from specific to general theories and prior researches on voltage sag and problems associated with it. Quantitative Method: Along with the quantitative approach, this study will use a statistical procedure and test the theory by analyzing the relationship between the variables that will include a survey and thorough study of the statistics surrounding the voltage sag problem and its problems. Mixed Approach: In order to determine the conclusion, the research will take an account of both quantitative and qualitative approaches and the subsequent data collected from the approaches, specifically as regards the subject of voltage sag and its associated problems. A design will then be established, that will include power quality practicalities as well as the theoretical framework. Research Design In the quantitative approach, the study will select a survey that will determine the trend, and opinions of the power utilities with the help of cross-sectional questionnaires and structured interviews. According to Ogden & Goldberg (2002), questionnaires are inherently quantitative. They focus on numbers and estimates based on the accuracy of responses or the similarity of the same. In this case, the issue is to ensure that a great percentage of acceptable questionnaire responses represent the majority opinion. It is however not off the mark to represent other unpopular perspectives to the matter. The questionnaire design will thus incorporate less personal questions few leading questions and majorly ones where the respondent simply has to tick where appropriate. The questionnaires will be evaluated with the interviews to establish quality of the responses and the level of bias on the responses produced by both sets of methods. For the qualitative approach, the study will take case studies of three instances where voltage sag caused some destruction in order to provide a clear understanding on the problems of voltage surge and its solutions from a practical point of view. Figure 1 below shows the research design in accordance to the three approaches as discussed above: Figure 1: The proposed research design to be adopted for Voltage Sag Study Research Strategy The research will follow a research study as shown in Figure 2 below: Figure 2: The proposed research strategy for the Voltage Sag Study The research will be conducted in a three phase strategy. The first two phases will be more off preparatory stages while the last phase will be more data oriented. The initial phase will involve review of back ground material on the subject matter – Voltage Sag Problems and Solutions. This will involve extensive reading, review and taking notes of written information on the research topic. Valuable materials in this phase will be electrical power reports, journals, expert reviews and other documented details that define the general state of voltage sag. This will present a firm basis and extensive grasp of the research topic. It will also provide the researcher with extensive valuable information that will subsequently be used in the preceding stages of the research. The second research strategy will be analysis of the research question. In the initial phase, major emphasis was on getting access to all valuable information on the topic of study. In this second phase, more effort is now directed towards analyzing and internalizing the research question. It also involves obtaining literature reviews on the research topic. Effort will be to analyze the available information in relation to the research question. This will be vital in sorting out the most relevant information from the whole lot of available data (Vithal & Jansen, 2007). The third phase will involve actual data collection, data analysis, data processing, writing of drafts and compiling of the final report on the research undertaking. This will be the most tedious and demanding phase of the whole undertaking. Research Philosophy The philosophy for this research will be positivism, as this topic should be studied in a scientific manner and based on facts surrounding the voltage sag problem and its possible solutions. It will also take the philosophy of axiology that determines surveys and statistical analysis in order to collect data for this research (Ogden, & Goldberg, 2002). Data Analysis The collected numerical data from power users as well as power producers and distributors shall be processed, analyzed, and later subjected to comparisons and contrasts in order to establish the views of other scholars, power engineering experts and columnists on the issue of voltage sag and its problems. The responses from quantitative survey questionnaires earlier on administered to power utilities will also be analyzed and scrutinized using the 7-point Likert Scale (Vithal & Jansen, 2007). Since the research involves three case studies, it will be easy to identify credible responses for subsequent documentation. In order to increase on effectiveness and accuracy of the collected data, the questionnaires will be designed in a way as to seek suggestions from the respondents on the possible approaches to help in the improvement of the problem of voltage sag. Justification of Preliminary Research Findings As was explained in the research problem, and based on the literature review provided herein, various hypotheses and expected research results were put forward. These hypotheses are convincingly justifiable on their own merit. First, it is expected that the findings will point to the fact that voltage sag is brought about by three main causes i.e. faults in the transmission line, starting of the induction motors, and the energizing of the transformer. This hypothesis is highly justifiable if the information contained in the literature review carried out in this research paper is anything to go by. In the literature review, for example, it is agreed that faults and starting of induction motors are a major cause of frequent voltage sag problems for power utilities (Dugan, Mark, Surya, & Wayne, 2003). The second hypothesis for the research is that some of the solutions to voltage sag problems include the use of electrical and electronics equipment whose tolerance is slightly higher to cushion them from voltage sags (Han, Jiang, & Le, 2003), implementing the use of coil hold-in devices mainly to counter the effect of voltage sags on contactors and individual relays (Marty, 1997), adjusting the power being supplied to the equipment in question, and setting up power conditioning devices. The information available on voltage sag and problems associated with it is in absolute agreement with this preliminary result for this research. It is known, for example, that Constant Voltage Transformers (CVTs) are a source of voltage sag ride-through. Conclusion In conclusion, therefore, it is agreeable that voltage sag can be one of the most costly forms of power problems if taken for granted by power utilities as well as power producers and distributors. It is recommended, therefore, that irrespective of the magnitude of the effective power the user uses in their equipment and systems, it is mandatory that they employ some of the voltage sag problem solutions discussed herein. It is, however, important that an understanding is sought on the difference between power interruptions and voltage sag as the two are completely different. While voltage sag is all about a drop in the effective voltage in a system or electronic equipment for a significantly short period of time, power interruptions involve a complete lack of power for however long it takes. References Bollen, M. H. J. (2000). Understanding Power Quality Problems: Voltage Sags and Interruptions. New York: IEEE Press. Dugan, R. C., Mark, M., Surya, S. & Wayne, B. H. (2003). Electrical Power Systems Quality. McGraw-Hill Companies, Inc. Han, Y., Jiang, Q., & Le, J. (2003). Modern power and FACTS and DFACTS technologies. Electrical Equipment, vol. 4, pp. 5-10. Khalid, S. et al. (2011). Power quality issues, problems, standards & their effects in industry with corrective means. International Journal of Advances in Engineering & Technology (IJAET), vol-1, issue 2, pp 1- 11. Le, T., Lamoree, J., & McGranaghan, M. (1994). Distribution system voltage sags: interaction with motor and drive loads. Proceedings of IEEE/PES Transmission and Distribution Conference, Chicago, USA, 1994. Marty, M. (1997). Common power quality problems and best practice solutions. Shangri-la Kuala Lumpur, Malaysia 14. Math, H. & Bollen, J. (2000). Understanding power quality problems: voltage sags and interruptions. IEEE Press, New Delhi. Ogden, T. E., & Goldberg, I. A. (2002). Research proposals: a guide to success. San Diego, Calif, Academic Press Sankaran, C. (2002). Power Quality. CRC Press LLC. Shailesh, M., Deshmukh1, B. D., & Gawande, S. P. (2013). A review of Power Quality Problems-Voltage Sags for Different Faults. International Journal of Scientific Engineering and Technology, Volume No.2, Issue No.5, pp. 392-3971. Styvaktakis, M., Bollen, H. J., & Gu, I. Y. H. (2000). Classification of power system events: Voltage dips. 9th International IEEE Conference on Harmonics and Quality of Power, Orlando, Florida USA, Vol. 2, pp. 745- 750. Vithal, R., & Jansen, J. (2007). Designing your first research proposal: a manual for researchers in education and the social sciences. Kenwyn, Juta. Read More

This information is also significant in helping the users to note and understand the various causes of voltage sag with the aim of attempting to manage voltage sag events when they occur within their jurisdictions. Two main factors are significant in determining whether indeed the impact created by voltage sag occurrence is intense or not. These are strength and time-frame within which the sag occurs, and the sensitivity of the equipment being used. Some of the electronic instruments that are quite susceptible to voltage sag include motor starter contactor; PLCs, control relays, and speed drive controls (Math & Bollen, 2000).

Unfortunately, this information is particularly not with the very end users of most of this equipment. This, therefore, necessitates the implementation of such a research as this particular one so that not only users of this power may be aware, but also the power producers and suppliers alike. At the end of this research, therefore, certain specific outcomes are expected. They serve as the hypotheses for the research. First, it is expected that the findings will point to the fact that voltage sag is brought about by three main causes i.e. faults in the transmission line, starting of the induction motors, and the energizing of the transformer.

The second hypothesis for the research is that some of the solutions to voltage sag problems include the use of electrical and electronics equipment whose tolerance is slightly higher to cushion them from voltage sags, implementing the use of coil hold-in devices mainly to counter the effect of voltage sags on contactors and individual relays, adjusting the power being supplied to the equipment in question, and setting up power conditioning devices (Bollen, 2000). Literature Review Voltage Sag Explained Voltage sag is not necessarily a total lack of power, but a temporary fall in the effective voltage in electronic equipment or the power supply and distribution system that typically occurs usually in a period of less than one minute (Dugan, Mark, Surya, & Wayne, 2003).

It has always been the desire of most utilities to ensure a secure and reliable electric power within their premises. Their desire, however, has always been thwarted by voltage sag is attributed to very many causes that keep varying always. This has been a challenge in the sense that even when users prevent their utilities from a certain cause(s) of voltage sag, there are still other causes that will remain unmitigated at all times which continues to leave them vulnerable (Sankaran, 2002). Causes of Voltage Sag Of the many cause of voltage sag, storms have been reported as the most prevalent causative agent of voltage sag especially in external environments.

According to Dugan, Mark, Surya, & Wayne (2003), when a storm occurs, it leads to several instances of variations in the supply of power to different users. In the course of this, voltage sags also have a higher likelihood of occurring. System faults are also a major cause of voltage sag. According to Math & Bollen (2000), when faults occur, the operations of a power plant and other industrial utilities are interfered with in one way or another. The extent of damage, however, largely depends on whether the fault is symmetrical or asymmetrical.

For a symmetrical fault, the strengths of the resultant voltage sags are of equal magnitude in each phase, while for asymmetrical faults, the resultant voltage sags have magnitudes that are not equal (Dugan, Mark, Surya, & Wayne, 2003). System faults that may lead to voltage sags are such that their magnitudes are largely affected by such factors as the impedance of the fault, the pre-sag voltage level, the manner in which the system is configured, and the type of fault (Bollen, 2000). Starting of induction motors is also a source of voltage sags.

It is indeed a known fact that induction motors are usually balanced at 3 loads (Dugan, Mark, Surya, & Wayne, 2003). This, therefore, makes the voltage sag arising from their starting to be symmetrical in nature.

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