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16Journal of Siberian Federal University. Engineering & Technologies, 2018, 11(5), 528-535
y^K 621.311
Development of Procedures for Determining the Optimal Placement of Symmetration Devices for Electrical Supply Systems 0.4 kV with Motor-Actuated Load
Viktoria V. Romanova, Sergey V. Khromov and Ivan F. Suvorov*
Transbaikal State University 30 Aleksandro-Zavodskaya Str., Chita, 672039, Russia
Received 21.10.2017, received in revised form 01.02.2018, accepted 16.05.2018
In this paper, we consider the development of methods for determining the optimal location of symmetrization devices for 0.4 kV power supply systems with motor-actuated load. The methodology includes the features of electric consumers and their geographical location. The practice procedures for application of the existing power supply system the Taptugary village, the Mogochinsk region, the Trans-Baikal Territory was given as an example. The practical significance for the developed application procedures was justified. The optimal solution of balancing problem based on economical parameters was obtained.
Keywords: power supply system, voltage asymmetry, asynchronous motor, power losses.
Citation: Romanova V.V., Khromov S.V., Suvorov I.F. Development of procedures for determining the optimal placement of symmetration devices for electrical supply systems 0.4 kV with motor-actuated load, J. Sib. Fed. Univ. Eng. technol., 2018, 11(5), 528-535. DOI: 10.17516/1999-494X-0051.
© Siberian Federal University. All rights reserved
Corresponding author E-mail address: sergeixrom@inbox.ru, romanova181@mail.ru
Разработка методики определения
оптимального размещения устройств симметрирования для систем электроснабжения 0,4 кВ с электродвигательной нагрузкой
В.В. Романова, С.В. Хромов, И.Ф. Суворов
Забайкальский государственный университет Россия, 672039, Чита, ул. Александро-Заводская, 30
Рассматриваются вопросы разработки методики определения оптимального размещения устройств симметрирования для систем электроснабжения 0,4 кВ с электродвигательной нагрузкой. В методику заложены особенности электропотребителей и их географическое расположение. Приведен пример применения методики для существующей системы электроснабжения с. Таптугары Могочинского района Забайкальского края. Дано обоснование практической значимости применения разработанной методики. Получено оптимальное решение вопроса симметрирования исходя из экономических показателей.
Ключевые слова: система электроснабжения, несимметрия напряжений, асинхронный двигатель, потери мощности.
Introduction
At present the power quality (PQ) problems are paid particular attention. Under current conditions, the power quality indices (PQI) such as voltage asymmetry and non-sinusoidality have become indispensable factors, which reduce the performance of the power supply systems themselves significantly and their connected consumers accordingly.
According to the research of the basic power quality indices in 0.4, 6 and 35 kV network nodes of the Trans-Baikal Territory power system it was found that deviation of the basic PQI such as voltage asymmetry and non-sinusoidality is a permanent factor during operation of the Trans-Baikal power system networks. In a number of cases the asymmetry level exceeds the GOST 32144 - 2013 [1] rated value [2] (by 2 - 3 times).
Due to unsatisfactory condition of PQ in the Trans-Baikal power system distribution networks, a great number of electric equipment failures at the consumers' facilities is observed. According to damage rate analysis of asynchronous motors (AM) at the Trans-Baikal Territory enterprises during 2015 - 2016, a large number of motor damage cases was registered in different sections of the Mogochinsk region. The emergencies are mainly associated with the voltage asymmetry of the supply mains.
The electric equipment reliability and performance is directly related to PQ in the distribution networks. For steady-state operation of the power-consuming units it is necessary to carry out a number of actions directed at PQ improvement and at voltage asymmetry removal, in particular.
Within this work framework, one of possible actions for PQ improvement, due to introduction of balancing devices into power supply system (PSS) at the designing stage is proposed.
This work scope is development and approbation for determining the optimal location of symmetrization devices for 0.4 kV power supply systems with motor-actuated load (using the example of the Trans-Baikal Territory).
Task setting
In accordance with the set goal the task on development of the power supply system calculation algorithm subject to using the balancing devices and their installation locations was implemented, based on which the procedure will be built. The diagram for calculation algorithm of the power supply system subject to using the balancing devices and their installation locations is given in Fig. 1.
Based on the experimental research data of the basic PQI, the information on the value of power loss in the elements of the power supply system under study, and, in addition, relying upon customers' allowable operating modes, it is possible to select the parameters of the balancing devices and determine the optimal location of these devices in the power supply system. Thus, the calculation of the value for supplementary power losses due to voltage asymmetry will enable to define the economic feasibility for carrying out particular actions for asymmetry removal, and besides, to specify the optimal application and location of these devices.
Fig. 1. Block diagram for calculation algorithm of the power supply system subject to using the balancing devices and their installationlocations
Researchresultsand their discussion
The developed procedure is a matter of interest during development of projects for power supply systems for regions with available non-li near loads.
The main criterion for the procedueeapplication consists in excess of the voltage asymmetry coefficie nt statistical value ((gn)innegative-phase sequence for this PSS over the allowable value K2U forAM (Table 1) installedin the same power supply system. The required k2U value is selected based o nthe customer's allowableo perating mode. The values of the allowable value K2U for AM are taken from the research results [3].
The procedure cun tie cmplomented in thefollowing sequence:
1) tet us determine tOe tneoes foe symmetrical operating modes in the main elements of the power supply system.
Caloulatlan oe supplementaiyp ower losses is made by formulas given in [4].
The lssnts fc Che fowen toansmirsien lines are determined based on the expression:
¿PpTL = t Zlrph, (1)
where I - symmetrical operating mode current (positive-phase sequence current); rph - phase conductor resistance.
Real-powcr AP' and tnac-tve Cr<ef pfwer losses for double-wound transformers are determined based on the expression:
AP
AQ' =-20-', (3)
x 100n Srt'
where Pk, Uk, Srt - nameplate data of individual transformer; S - substation full load (total of individual transformer loads); n - number of one-type transformers in the substation, parallel operating.
2) let us determine the losses for asymmetrical operating modes in the main elements of the power su.pfy sj^tem.
Tha odoitableamplitudeenO angulao asemmeityduringetgimation of increase of supplementary losses as compared to symmetrical operating mode can be accounted using the coefficient Kas:
Kas — 1 + K2J -I- ATojt
O+f (4)
RPHJ
where K2I, K0I - coefficients for asymmetry of negative-phase and zero-phase sequence currents. Based on the results of processing the statistical data for basic PQI in 0.4 kV network nodes of the Mogochinsk region, the Trans-Baikal Territory, we take on the values equal to K2I = 5%, K0I = 4.6%, K2U = 4.95%; Rn, Rph -resistancesoftheneutraland phase conductors.
Tablel.Table ofallowablevalues K2U
Motor model Motorpower, PL, kW Allowable value K2U, %
4A132S4Y3 7.5 1.8
AI132M4 11 1.26
Accordingly, taking into account (3), the expression (1) will be as follows:
kO'sUPL.PTL = ^PpTL^as . ()
TOe snppto meneasy losves ed ebr real-power via the asynchronous motorure determined based on thf engrossim
^PsnPLAM = e>41fccpi''C2nJ—- in)
whore kAM - the coefficient, accountingthe particular motor parameters (rated power, stator copper losses, starting current-to-rated current ratio); K2U - coefficient of voltage asymmetry in negative-ohase tepuhnce; PL -e ratedmetorrealpowwr.
The -oeffitieni ^ vdue fermduvtaM na^yrn^^ ;oad is kdvihep ik tflay osei equal to 1.85. D uringto ^-Busta^d avymmetrical operating mode, due to the flow of negative-phesesp quenre cAurentst tle^ cupptymLitLasy power 1osspi asour in the power transformers, which cap bedeteomtned bythe SbUowmjo fosmulh:
= O (Ap,* -If hS (7)
where K2U - the voltage asymmetry coefficient in negative-phase sequence; APIM - losses during idle mode; i^hic-loasei dvoine shortrtievrnt mt^ posc - storticircuih eolttgs.
c) Oat ut ptoceetl io fakinp thn specislmeasufes for removal of the voltage asyrnesemr0 end slistsaaniiocosiiso oV tieu ojsltof^ pppiiceeeoo anIe lovpteon ttf tliose devices.
Lel es ca^rssil^^^ ^i^^is^lti mal location and selection of the balancing devices. The fellow(nnsuetasks shall bu soOced fee thit purpose:
a) detect the motor, which is most sensitive to voltage asymmetry out of all motors present in the powcc ciyuyfy sesten^
bl delernune ttie khunr for к)кmmDttseoo>erating mode in the main elementsofthepower se^tfy sy utem wist ins^ed UcSancicg deo Sc^ in tie central nciC ctp tie lit agtanoCaOhodcOe tli^ flyback j^^riod C(ur instsVietion ofthebalantinn deelce.
CaSi^s^1atit^l^ ofth^iic^btick nsetod ics ic^tta^1slii^n oflhs balansinn devleeaunbe detsrmined by tPa foaiciw ingformula:
S
pp =_ (8)
((APsupl. w + VQsupl. w) - (VPsupl. +VQsupl.)) * C'
wliei^^ PP - the paybacK perihd; S- the total cost of the installed balancing devices; AUsupl. w g AQsupl. vr - supplementary losses without the balancing devices; tbaanC. +AVaanC. -supplementary losses withthebalancing device; C - the costof theelectric power.
c) determine the losses for asymmetric operating mode in the main elements of the power supply system with installed balancing device in each motor individually. Calculate the payback period for installation of the balancingdevice,
d)basedoncalculation results analysis select the most optimal option,
e)carryoutinstallationof thebalancingdevicein the power supply system.
ettonTo implement the procedure let us consider the power supply system section of the Taptugary village,the Mogochinsk region,theTrans-BaikalTerritory.
The following reference information was used for execution of this work:
1) the results of processing the statistical data for basic PQI in 0.4 kV network nodes of the Mogochinsk region, the Trans-Baikal Territory,
2) the configuration of the power supply system section of the Taptugary village, the electric power consumers' characteristics.
The power supply system, on which the procedure was approved, is given in Fig. 2. The power supply system section diagram consists of:
1) line 1 - wired with AS-25 (steel-aluminium conductor), the line length is 350 metres, feeds 7 private res idencehous eswithfurnacehe ating,
2) line 2-habled withGRSh 3*50+1*35 (eaMewhhflexMe coee, rubbe r coverendpofy am[de silk isolntion), tOo Vice Sengt5 io 50 merres, deeds the two -atoaeyel residence horse, iheerimaaysniiool, the kindeegari5n,lha aOmonialralioibueiding and the library,
3) llne5 -cabredwithAVVshv h^O )cabiewimh aluminium aora,PVC jacket, with protective layer in Oheformofpressedmui hosoi, ihe torn eeroth is7nmettit, ieed) ohe boiler house with two boilers anU mnioas: themoUei2A030S4Y3 Pl27.5 kW, C ores., tlre emoVe oehomsl fan P^O S^ihr, the d raugOefanPLag.4OW,
4) line 4 - wired with SIP 4*25 (self-supporting insulated conductor), the line length is 150 metres, feeds two ban mills with motors model AI132M4 PL=11 kW, 2 pcs.
Calculation of the power supply wiring diagram was made using the widely spread computer program Microsoft Office Excel. Main calculation results are summarized in Table 3. The cost indicato rsare tetenfiomlhes ooocea[0, 6].
Tliuo, foUowingiligcalculatio n results we obtained the value of power losses in the main elements of the poworauppl0 tysrem foethe cymweieicalopereticg rnoda,0lt osymmetricol opeooti^mode wtlltour device and the asymmetrical operating mode with installed
balancing davice. Baiol cat she data of oesulla (e(us ealermiuethenumber,poGerandOhelhootion for intlaeioOion iOiCo Oolaooicgdhviee.
|<3>j TM 1000/10/O.-
□ □
Line 1
Line 3 Line 4
Fig. 2. Power supply system section diagram of the Taptugary village
Table 2. Reference data of the village Taptugary network section
Parameter Line 1 Line 2 Line 3 Line 4 TS
Power, kVA 30.4 49.4 20.9 25 100
Current, A 80 130 55 65.7 330.7
Table 3. Calculation of payback period for installation of the balancing device based on supplementary power losses
Losses AP +AQ, kVA
1) During symmetrical operating mode 17.0+j16.0
2) Supplementary losses during asymmetrical operating mode
without balancing device 8.4+j0.2
during installation of the individual balancing device in the motor - option 1 2.5+j0.2
during installation of the common balancing device in all motors - option 2 2.7+j0.2
3) Cost of balancing devices, thu. rbs. -
Balancing device PL = 9 kW 39
Balancing device PL = 11 kW 45
Balancing device PL = 45 kW 126
Cost kW*hour, rbs 5
Total cost of BD (balancing device), option 1, thu. rbs. 168
Total cost of BD, option 2, thu. rbs. 126
Payback period, option 1, months 8.28
Payback period, option 2, months 5.95
Analysing the data given in Table 3 the conclusion can be made that for considered diagram it is economically viable to install one balancing device with 45 kW power on the common node of the lines 3, 4, containing the motor-actuated load, but not the individual one on each motor.
Following the results of the procedure implementation we found the necessity for application of the balancing devices for industrial consumers in the diagram under research. We selected the most cost-effective location of the balancing device in PSS.
It is evident that only upon available reliable information about the levels of PQI distortion, about the operating modes of the power consumers it is possible to make up the requirements specification for PSS designing and to select the optimal parameters for the balancing devices.
Conclusion
The developed procedure is of practical interest for designing of 0.4 kV power supply systems containing the motor-actuated load under voltage asymmetry conditions. The specifics of the electric power consumers' operating modes and their geographical location are built in the procedure.
Application of the procedure in PSS with available motor-actuated load will allow increase the operating reliability and efficiency of the asynchronous motors.
The proposed procedure will be the basis for implementation of the task for creation of the software complex allowing to make quick and accurate calculation of the power losses, to determine the economical feasibility of provision special measures for removal of the voltage asymmetry, for determination of optimal application and location of the balancing devices.
The work was executed within the framework of FSBEIHPE Trans-Baikal State University Council for Research and Innovative Activities Scientific Grant No. 247 - GR of 30/01/2018 implementation.
References
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