SUMMARY OF PhD THESIS

Transcription

1 FACULTY OF ELECTRICAL ENGINEERING Eng. Paul-Dan MUREŞAN SUMMARY OF PhD THESIS ELECTRICAL POWER EFFICIENCY IN DISTRIBUTION SYSTEMS PhD Advisor, Prof. PhD. eng. Virgil MAIER Evaluation commission of PhD thesis: PRESIDENT: - Prof.PhD.eng. Radu CIUPA - dean, Electrical Engineering Faculty, Technical University of Cluj-Napoca MEMBERS: - Prof.PhD.eng. Virgil MAIER PhD Advisor, Technical University of Cluj- Napoca - Prof.PhD.eng. Gheorghe LĂZĂROIU - referent, Politehnica University of Bucharest - Prof.PhD.eng. Radu D. PENTIUC - referent, Ştefan cel Mare University of Suceava - Prof.PhD.eng. Sorin Gh. PAVEL - referent, Technical University of Cluj-Napoca.

2 Lately, we are witnessing an overall population increase throughout the world. As a result the energy consumption is also growing together with a dramatic drop in resources. Therefore, due to the negative impact on the environment as well as the consequences of global warming, society is facing three extremely complex issues economical and demographical growth, the energy and resources consumption, preserving the environment. We might say that the world is facing an unprecedented trilemma. Issues concerning energy have become a general preoccupation of nowadays society. The energy efficiency growth has a major impact in the safety of food processing, durable development and competiveness, economizing primary resources and reduction of gases that cause the greenhouse effect. Thus, the European Committee has come up with a set of measures in order to impose a new European policy concerning energy. These measures are meant to stop the changes in climate and stimulate the security and competiveness of the energy sector. The European Committee came up with a set of documents that represent The New Energy Policy of the EU with the following objectives: - reduction of gases that cause the green house effect with 30% by year 2020, compared with 1990; - a growth in renewable energy in the total energy mix, from less than 7% in 2006, to 20% of the total energy mix by 2020; - a growth to at least 10% for the bio-fuel in the total fuel usage by 2020; - a reduction of 20% in the primary energy usage by The great interest in economizing and rationalizing the energy consumption derives from the fact that the planet s natural resources are limited. Consequently a growing number of countries are overseeing the reduction of energy loss, improvement of energy consuming installations, as well as redesigning the production technologies in order to insure specific energy consumption as low as possible. For this purpose, the first step that must be taken is to determine the energy balance, the useful energy used throughout the operation circuit versus the absorbed energy, as well as determining the necessary expenses in order to optimize the energy balance. This is where the terms real energy balance and optimal energy balances derive from. The purpose of the thesis - Electrical power efficiency in distribution systems is to establish a methodology that allows determining and analyzing the efficiency growth through 2

3 consumption reduction in distribution systems. The main method used is the energy balance, which allows both qualitative and quantitative analysis of the way energy is used within a predetermined system (counter). Elaborating and analyzing the electro-energetic balances is the most efficient way to establish the technical and organizational measures that will lead to a growth in the performance of the energy used in a system and diminishment of consumptions. The electro-energetic balance analyzed in the thesis, on Baciu power station for 110/20/10 kv, has as purpose the enhancement of quality, establishing the ideal consumption structure and reducing the energy losses in order to attain the best energy-technological parameters. Through its approaching the hereby thesis contributes to solving the multiple issues that specialist in the energy field are facing and through the energy balance it offers an efficient way to use as rational as possible the available energy resources. The studies that have been conducted within the thesis, show the fact that the loss reduction in distribution systems is far more economical than enhancing the generating capacities and energetic efficiency is the cheapest existing resource. The thesis is structured in six chapters and its content is organized as follows: Chapter 1 outlines the current structure of the national energetic system. It also deals with its components (aerial and sub terrestrial lines, transformers and so on), functioning regimes and types of consumers. Chapter 2 is dedicated to calculation of electrical parameters of all the elements that are part of a distribution system, considering the determination errors as well. The software, which was created in order to determine the temperature of the conductors and the LEA parameters from exploitation, is detailed at the end of the chapter. Chapter 3 outlines the calculation of energy drop and loss in the pre-determined system considering the relative determination errors. Towards the end of the chapter power loss within the balance components and their relative errors are determined. Chapter 4 details the elements that can be found in the electrical balance equation, the calculation of loss within the electrical lines and power transformers, reactance coils and compensation batteries, as well as energy loss derived from measurement equipments and commercial loss. The necessary measurements in order to determine the electrical balance as well as the necessary apparatus are also detailed here. This chapter closes with diagrams of 3

4 electrical connections of tri-phased and mono-phased counters that are used for eluding electrical energy. Chapter 5 details measures for reducing the energy consumption both without costs and also measures that require important investments. Furthermore, certain methods for reducing energy loss within power lines and transformers, as well as reducing the reactive power in electrical lines, are detailed. Chapter 6 presents the elaboration of the electrical balance on a working day and within a calendar month for Baciu power station. The real balance of the input and output energy from the system on April 11 th, 2010 Table 6.2 No Specification Input Output ΔW kwh kvarh ε r % kwh kvarh ε r % kwh kvarh ε r % 1 Input 110 kv Transformer 25 MVA Transformer 16 MVA Outgoing 10 kv Outgoing 20 kv Total Conventional power transformation efficiency is defined in [83]: (1 W ) W i ,43, %. (6.1) 4

5 Fig Sankey diagram for Baciu power station on the 11 th of April Fig The closure of the electrical balance for Baciu power station within one calendar day: a) without considering the errors; b) considering the errors; c) same, with an increased error zone. 5

6 Should we determine the balance components without assessing the determination errors, the closure error (fig. 6.10, a) is: W % W i Wu W i W 100 0,6%. (6.2) If the errors of the balance have been estimated for the input and output, the result that comes from the intersection areas of uncertainty is a non-empty values domain, so the balance was closed without an error of closure, figure 6.10, b. When elaborating optimization methods for a real balance one needs to take into account those data whose efficiency overpasses as value the error domain for determining that certain data. The balance closure lot for the energy balance on the 11 th of April at Baciu power station is different to null and is equal to the following: { W i r1} { Wu Wp r2)} [ r2; r1] [ 2.025; 2.079]% Wi. (6.3) In order to find some methods to optimize the technological consumption, this chapter ends with a simulation of the power station in EDSA, using Advance Power Flow resulting in the optimum functioning regime for the power station. CONTRIBUTIONS ŞI CONCLUSIONS (selection) Personal contributions The author s main contributions are the following: - Designing a Sankey general diagram for aerial power lines; - Designing a SEE main structure highlighting the tension levels, the main power station types and the types of connections within tension levels. - Determining the variation of loss that occurs through radiation and convection, based on the conductor type and the environment; - Developing the methods for determining electrical parameters of aerial and underground lines, including the estimation of total error and comparative assessment of these; 6

7 - Determining LEA electrical parameters upon exploitation, through implementing a software platform, that calculates the four parameters based on the wind speed, solar radiation, emissivity coefficient, absorption coefficient, environment temperature and so on; - Designing a calculation program of the LES resistance within continuous and alternative power; - Designing a nomogram for determining direct and reversed reactance of the conductors of a bare cord, set up on a medium voltage console; - Suggestion of a calculation method for the loss of active and reactive energy within the network elements; - Defining the tension drop and loss, as well as power loss, indicating the determination of relative errors; - The complete definition of the electrical balance equation, highlighting the total energy loss that may appear in the system; - The electrical balance closure of the power station considering the determination errors of the balance components; - Elaboration of electrical tri-phased and mono-phased figures for eluding electrical energy; - Elaboration of the electrical balance of Baciu power station, considering the relative errors of determination for the values used in the balance; - Designing Baciu power station using EDSA program; - Computer assisted analysis of the functioning regime of Baciu power station in order to determine the optimum functioning regime, using EDSA; - Suggestion of an optimization method for Baciu power station s own technological consumption Conclusion Enhancement of electrical efficiency upon all the segments of an energy system has a major contribution in economizing the primary energy sources and thus reducing the gases that cause light house effect. Optimization of energy processes also contributes to sustaining durable development and competitiveness growth. 7

8 Development and usage of various methods in order to determine the calculation parameters of an energy system, such as power lines, allow the choice of the best out of them, for each specific case. The aim is to use the measurements apparatus as efficient as possible in order to determine the parameters and the balance elements with minor error. Due to the fact that each determination method of a value or parameter has a certain error it is considered a permanent necessity to determine and consider the error of each value. This has allowed the estimation of the total error, a more accurate determination of consumption and loss, as well as the closure of the electro-energetic balance considering the above. The software detailed in the thesis allows the determination of LEA exploitation electrical parameters, highlighting the diminishment of energy loss, calculation errors and costs of the electrical energy. Methodological adaption of the electro-energetic audit to current condition is imposed by the following evolutions: - related to the measurement equipments such as electronic counters, far more versatile than a classical apparatus assembly; - related to the science field, through elaboration of new determination and analysis methods, through precision growth by comparison to traditional methods. An accurate knowledge of all the parameters of a system s elements is the essential for a correct elaboration of electro-energetic balances and determination of the optimization measures. Establishing the optimum configuration, both in designing-developing phase as well as exploiting phase, in real functioning conditions, has great importance in minimizing own technological loss and functioning safety. All of the aspects that must be taken into account may have serious financial implications. Minimization of these costs is a core component of the energetic policy of any power producing company. The usage in this thesis of the facilities provided by EDSA program for the technical aspects (Advance Power Flow), confirm the utility of this program as a powerful calculation instrument. 8