Synthesis Procedure of the Power Supply Systems Topology at Mineral Resource Enterprises based on Logical-Probabilistic Assessments Denis Anatolyevich Ustinov and Sergey Vasilyevich Baburin National mineral resources university (university of mines) 2, 21st line, Vasilyevsky Island -199106, St. Petersburg, Russian Federation Abstract The article considers synthetic procedure of the power supply systems topology at mineral resource enterprises. The expediency of using general logic probabilistic method and developed on its basis the software "ARBITR" is substantiated to calculate the reliability of power supply systems. The results of the synthesis topology of power supply systems are cited as an example of consumers with underground mining operations and consumers of gas transmission systems. Recommendations are given for raise the reliability power supply of enterprises mineral complex. Keywords: reliability, power supply system, the logicalprobabilistic method, significance, autonomous source. Introduction The main type of energy used in the process of production, processing and transportation of solid, liquid and gaseous mineral resources is electrical energy. Power supply systems (PSS) objects mineral resource complex (MRC) should provide consumers with electricity with a given level of reliability, which is determined primarily by the following parameters: probability of failure-free operation for a given period of time, availability factor, the depth and duration of voltage dips. By the power supply disturbance emerge problems associated with the disorder complex technological processes, leading to considerable material damage with the occurrence of risk to human life, etc. Analysis of the power supply systems topology has allowed to reveal the generalized structure power supply system enterprises MRC, including devices improve power supply reliability: sources of autonomous power supply (APS); Automatic sectioning points (ASP); filter-compensating devices (FCD); fast-acting automatic input of a reserve (FAIR), devices control circuit under voltage of power transformers (fig. 1). On the fig. 1 is not shown power supply of busbar 6 (10) kv from centralized systems power supply of 35 kv, 110 kv, 220 kv through the step-down transformers main step-down substation, and also set of customers and converters of electric power, receiving power from the busbar means of radial, radial-trunk and ring power lines. In conditions of centralized systems power supply with closed structure, voltage dips under emergency conditions arise on all inputs, which does not regard them as independent sources. [1] According to the Energy Strategy of Russia until 2030, approved by the RF Government from November 13, 2009 1715-r, it is necessary to increase the probability of deficitfree operation of power systems of Russia with 0.996 to 0.9997, which corresponds to a decrease the allowable number of switching-off hours per year from 72 hours to 36 hours, including the time of regenerating of power supply. [2] Standards, constitutive requirements for indicators of reliability and stability of PSS and stability of technological processes at disturbances of power supply are lacking, hence the need for works realization at establishing the boundary parameters that must be provided at the facilities of MRC. According to State Standard R 54149-2010 "Quality standards of electric power in the power supply systems, general purpose", point 4.3.2.1 «Voltage dips' duration of the voltage dip can be varied from 10 milliseconds to 1 minute. However, this Standard does not impose requirements for the depth and duration of the voltage dip in power networks for specific and stability of technological processes at the enterprises MRC. As it was shown by studies and experience of operation of existing power supply systems, violation of technological processes in the oil industry arise during brownouts lasting 0.1 seconds.. Under the conditions of the petrochemical industry in emergency conditions occurring during a short circuit (short circuit) on one of the inputs and result in voltage dips to 0.3 from the nominal and during the process of liquidation of short-circuit 0.18 s, there has been a violation of the refining process, which led to the shutdown of 40 processing units with the appropriate material damage. Similar damage in case of a power failure occurs almost all branches the mining industry. Considering variety of industries in the MRC, it is necessary to establish the reliability of power supply, which provide stability of technological processes and develop method for the synthesis topology of power supply systems at MRC enterprises, properties and parameters which satisfy the requirements of the stability and safety of operation of technological objects of MRC. Research Results Justification of structure and parameters of the topology of the PSS should be performed using the methods of mathematical modeling in the process of variant structures for which shall be determined reliability, the number and value of the individual elements. Let us consider possibility of using wellknown methods for assessing the reliability of PSS and MRC based on their complexity and multiply By modeling it is advisable to use automated software systems. At the present time, the following software systems are used: «Risk Spectrum»; Complex by Prourzin V.A. 6402
numerical analysis of reliability; «BUNKER»; «RAY»; "Rizikon-reliability"; "ARBITR". In most of the above adducted software systems studied structures presented as event trees, fault trees or graphs of connectivity. However, this presentation of events has some disadvantages: presentation of the structural schemes in the form of event trees, makes it possible to correctly present only monotonous process of functioning of systems that cannot account difficulty in the models designed facilities; construction of fault trees demands the account of all possible variants of events, sequences and combinations is difficult by considering the complex, interconnected systems. These disadvantages are eliminated in the program complex for automated structural logic modeling of systems "ARBITR" [3]. In this method, as the original structural circuit the scheme of functional integrity (SFI) is used, showing the original system consisting of power and included in their structure elements. SFI is a block diagram in which functional tops (large circles) are marked the components of the real of power supply. They linked to each other with conjunctive and disjunctive contacts which characterize the logical connection of components. For each element are set its parameters. As examples two schemes of functional integrity of consumers with underground mining operations and consumers of gas transmission systems are considered below. Fig. 2 shows a generalized system SFI of power supply at gas pipeline compressor station (CS "Torzhok" of "Gazpromtransgaz St. Petersburg"), and fig. 3-SFI generalized system of power supply of mining consumers (mine Vorgashorskaja stock corporation "Vorkutaugol"). Initial data for calculation are the values meantime between failures and mean time to repair each item. They are determined on the basis of statistical data or reference data [4]. After that, it set a logical criterion of operation, such as the probability of obtaining power by any users of the system, and makes logical functions of the system. A the result of modeling parameters are determined by power system reliability, such as uptime, mean time between failures, mean time to repair the system, the probability of failure-free operation for a certain period of time and indicators characterizing the role of the elements in ensuring reliability. These indicators include the significance of positive and negative contributions of each element [5]. The importance of the element shows an increase in the reliability of the system by increasing the probability of failure-free operation of the cell from 0 to 1, then there is the maximum possible improvement: P P. (1) i 1 0 In the fact the existing elements already have a probability of failure of non-zero (p i). Therefore it is more expedient to use in the analysis of the values of the positive contributions of the elements. They represent a possible increase in the reliability of the system by increasing the probability of failure-free operation of the element from its current value to 1, and then there is a real opportunity to improve the reliability: i Pc p P. (2) i 1 c p i The negative contribution on the contrary shows how reduced reliability of the system by reducing the probability of failurefree operation of the element from its current value to 0. That is, it shows the most vulnerable elements of the loss which are most affected the reliability of the system: P P. (3) i 0 As a result of modeling the power supply reliability for mine consumers are established the parameters of power supply reliability for conveyor belt, mining combine and face conveyor. They are indicated at the fig. 3 small circles 74, 80 and 85. For this example the results of the calculations showed that the ratio of system availability factor for the number 74 (conveyor belt) was 0.993, and for 80 (face conveyor) and 85 (mining combine)-0.987. However, the set value of mean time between failures is T 0 = 1391 hours for belt conveyor and T 0 = 472 hours for face conveyor. The average failure rate in the year was respectively 6.3 and 18.5. The probability of failurefree operation for the belt conveyor in one year amounted to P = 0.0018, face conveyor and mining combine-p = 10-8. As a result of modeling the significance, positive and negative contributions values of the system elements are obtained. The values of the positive contributions ranged from 0 to 0.0029, and negative contributions from 0 to 0.99306. Elements that have the highest values of positive and negative contributions for the SFI are shown at the fig. 3 in the table. From the obtained results it is possible to identify elements, failure of which will result in the greatest economic damage. For this scheme it is the cable lines, transformer substations and switchgears. At the same time, these elements also have the highest values of positive contributions. The results of modeling for the SFI compressor station (fig. 2) [6] are showed that the cells of indoor switchgear (3, 6, 19, 20, 22, 23) and transformers (28, 29, 31, 32) have the greatest importance. The values of the positive contributions range from 0 to 0.002, negative contributions-from 0 to 0.035. The analysis of the positive contributions of elements of electric power enterprises MRC is showed that their value does not exceed 0.003. So, increasing the probability of failure-free operation of power supply systems through the modernization of its individual elements is possible only by an amount equal to the positive contribution of this element. Therefore, ensuring required parameters of reliability is advantageously carried out by means of structural and temporal reserving based on the synthesis of topology power systems enterprises MRC. Such measures include: reservation of the most important elements of the system; the use of additional sources of electrical energy, the role of which can act as a traditional independent sources working on diesel or natural gas, as well as alternative and renewable energy sources; the use of high-speed automatic standby activation [7]; the use of storage in the system, allowing to create some leeway to eliminate failures [8]. This is the 6403
most common for transport systems, and it is achieved by a device such as intermediate storage. Uninterruptible power supply for the most demanding consumers of electric power interruptions who allow to create a reserve for the time required to recover the power from the main source. The results of logical-probabilistic modeling are the basis for the synthesis of the topology of power supply systems for enterprises MRC to determine the optimal variant of the power supply system and reconstruction of existing industrial plants [9]. Fig. 4 shows a synthesis algorithm for topology of power supply systems. The algorithm also includes a variety of options for power supply system of the economic criterion. As an economic criterion can be accepted the mentioned level of costs or the value of the net discounted income. There are cases when the system on the contrary has structural redundancy. In such systems, there may be elements that can be excluded without reducing reliability. In some cases other elements can be used instead of the most vulnerable elements. For instance, conducted researches for gas compressor stations with the use of logical-probabilistic of modeling are showed that the option of power supply scheme for compressor station with a two-part indoor switchgear and one section complete transformer substations (one transformer) is more preferable than the traditional scheme with two transformers, however at the same time the costs of establishment and operation of the electricity system of the compressor station are significantly reduced, and reliability satisfies the requirements of normative documents.. It was also found that the comparative figures for the reliability of self-contained power plants and transmission lines of the external network differ by an insignificant value-0.1%. It suggests the establishment of an equivalent power supply system using local power supplies, are not inferior in terms of the reliability of power supply from the external power supply system in non-electrified areas of the country Figure 1: Generalized structure of power supply system enterprises MRC. QF-automatic switch; TC-thyristor commutator. Table I: Importance, positive and negative contributions of the elements Number of element Importance Negative contributions Positive contributions Name of the element 49 0,0002279-0,00022787 2,6561E-008 SB 1 UDS 202 54 0,00013332-0,00013279 5,2466E-007 CL 6 KV 55 0,0040238-0,0040234 4,6896E-007 56 0,99318-0,99306 0,00011575 SB 2 UDS 204 SB 1 UDS 204 65 0,99365-0,99306 0,00058892 CL 6 KV 66 0,99596-0,99306 0,0029 TKSHVP 67 0,99596-0,99306 0,0029 TKSHVP 71 0,99322-0,99306 0,00015088 CL 1,2 KV 72 0,9932-0,99306 0,00013247 PVI 73 0,9932-0,99306 0,0001308 CL 1,2КВ Figure 2: Scheme of the functional integrity of the system of power supply efficiency of the compressor station. 1.4- overhead power line 110 kv; 2.5-transformers 110/10 kv; 3,6,10-12,19,20,22-26-cells of indoor switchgear 10 kv; 7-9- automatic gas-piston station (AGPS); 13,15,17-automatic control system AGPS; 14,16,18 block the ventilation AGPS; 27-32-transformer 10/0.4 kv; 35-38-system functions; y- output functions representing the conditions of the sale an element of functionality in the system. 6404
Figure 3: Scheme of the functional integrity of the power supply system for mining consumers. Power line-line of electric power transmission; QF-circuit breaker; SB-section busbar; CL-cable line; TSVP, TKSHVP-transformer substations; KRUV-Switchgear; PVI-starter; UDSunderground distribution substation Conclusions 1. It is substantiated the expediency of using general logic probabilistic method and developed on the basis of its software "ARBITR". Logical and probabilistic modeling allows to determine indication of the significance and contributions of components. 2. It is offered the method for the synthesis of the topology of power supply systems of enterprises MRC, properties and parameters which satisfy the requirements of stability and reliability, taking into account the complexity and the multiply of the constituent components and based on the identified indicators of significance and contributions of components in the ensuring of reliability to select ways to optimize the power supply system of the industrial enterprises, allowing to minimize the number of elements and reduce capital and operating costs. 3. For electric power supply of mineral complex enterprises is necessary to use the system with distributed generation by independent power supply, the use of which will allow completely or partially to abandon the centralized power supply plants MRC without compromising reliability. Acknowledgments Work performed as part of the job 13.707.2014/K from 11/07/2014 to Ministry of Education and Science Russian Federation. References Figure 4: Algorithm for synthesis topology power systems for enterprises MRC [1] ARBITR. Software for automated structural logic simulation and calculation of reliability and safety for the control system during the design stage (PC ASM SZMA), basic version 1.0. Author: A.S. Mozhaev. Rights holder: OJSC SPIC SZMA. Moscow, 2003. [2] M.S. Ershov, A.V. Egorov, V.A. Antsiferov Methods for assessing the reliability and independence of supply sources in industrial power systems, Promyshlennaya energetika, 2014, N 1, pp.2-6. [3] E.Kh. Muratbakeev, B.N. Abramovich, A.V. Medvedev, V.V. Starostin Minimizing the damage caused by oil due to short interruptions of power supply, Promyshlennaya energetika, 2009, N 7, pp.25-28. [4] V.A. Ovseichuk The reliability and quality of electricity supply to consumers, Novosti elektrotekhniki, 2013, N 3, pp.50-53. [5] S.P. Petrov, S.V. Baburin, D.A. Ustinov The use of logic and probabilistic modeling method for calculating the reliability of power supply systems, Nauka i tekhnika v gazovoi promyshlennosti, 2011, N 3, pp.47-50. [6] S.P. Petrov, B.N. Abramovich, S.V. Baburin Identification of optimization directions of energy 6405
structure on the criterion of reliability, Gazovaya promyshlennost, 2011, N 9, pp.82-84. [7] S.P. Petrov, A.N. Makhalin, S.V. Baburin Improving the reliability of gas transport systems with the use logic and probabilistic modeling method, Zapiski Gornogo instituta, 2012, Vol.196, pp.261-265. [8] RD 34.20.574. Guidelines on the application of power systems elements reliability parameters and work units with steam turbine installations. Мoscow: SPO Soyuztekhenergo, 1985, p.20. [9] A.N. Shpiganovich, V.A. Pestunov Improving the efficiency of functioning of the power supply systems, Elets: EGU im. I.A.Bunina, Lipetsk: LGTU, 2004, p.281. 6406