The problem of resonance phenomena in power systems of industrial enterprises using capacitor banks for reactive power compensation was detected. Circuit of the capacitor banks tier to downshift main substation tires ispresent. But there is no common algorithm to calculate and avoid such trouble. The main goal of this article is to introduce some basics for power supply systems with possible resonant circuits engineering

Bederak, Ya. S.

Gapon, D. A.

Purpose. The problem of resonance phenomena in power systems of industrial enterprises using capacitor banks for reactive power compensation was detected. Circuit of the capacitor banks tier to downshift main substation tires is present. But there is no common algorithm to calculate and avoid such trouble. The main goal of this article is to introduce some basics for power supply systems with possible resonant circuits engineering. Methodology. At the first step the data on the change of the current in the chemical company network when changing capacitor banks value are received. For these purposes the oscilloscope function of digital protection relay was used. Current data samples were analyzed by spectrum detection software. Most significant levels of the 3rd and 5th harmonics were achieved. Comparison of harmonic distortion levels with and without capacitor bank is given. Results. Achieved data allow making conclusion about overloading reasons of capacitor banks while higher harmonics currents presence. A voltage and current harmonious composition measuring in the absence of power quality analyzers using digital protection relay terminals or emergencies registers are proposed. The necessity of power quality monitoring near capacitor banks connections to avoid resonance phenomena (current and voltage resonance) in industrial power supply systems is proven. The control algorithm of capacitor banks to provide electromagnetic compatibility, while various modes of nonlinear load operation is given. Originality. Using of digital protection relay oscilloscoping for current resonant detection can allow to significally reduce time and cost of solution. Replacement parallel circuit comprising a branch and one active-inductive load to another branch network in the presence of higher harmonics source are proposed. Practical value. A sequence for measuring the levels of harmonic components at the connections of capacitor banks in the absence of specialized instruments is proposed. The algorithm to avoid possible resonance currents in the presence of condensing units is proposed.В статье рассматривается проблема резонансных явлений в системах электроснабжения промышленных предприятий, использующих конденсаторные установки для компенсации реактивной мощности. Приведены данные по изменению токов 3-й и 5-й гармонических составляющих в сети химического предприятия при изменении мощности присоединенных конденсаторных установок. Предложен способ измерения качества электроэнергии при отсутствии анализаторов. Разработан алгоритм обеспечения электромагнитной совместимости на присоединениях конденсаторных установок.У статті розглядається проблема резонансних явищ у системах електропостачання промислових підприємств, що використовують конденсаторні установки для компенсації реактивної потужності. Наведено дані щодо зміни струмів 3-ї та 5-ї гармонійних складових в мережі хімічного підприємства при зміні потужності приєднаних конденсаторних установок.  Запропонований спосіб вимірювання якості електроенергії в умовах відсутності аналізаторів. Розроблений  алгоритм забезпечення електромагнітної сумісності на приєднаннях  конденсаторних установок

Electrical Engineering & Electromechanics (E-Journal - National Technical University "Kharkiv Polytechnic Institute") / Електротехніка і Електромеханіка (Національний технічний університет - "Харківський політехнічний iнститут")

ЗАБЕЗПЕЧЕННЯ БЕЗАВАРІЙНОЇ РОБОТИ КОНДЕНСАТОРНИХ УСТАНОВОК В ЕЛЕКТРОПОСТАЧАЛЬНИХ СИСТЕМАХ ПРОМИСЛОВИХ ПІДПРИЄМСТВ

Library of National Technical University "Kharkiv Polytechnic Institute"

Електричні станції, мережі і системи  
56  ISSN 2074-272X. Електротехніка і Електромеханіка. 2016. №1 
© D.A. Gapon, Ya.S. Bederak 
UDC 621.311                                                                                                               doi: 10.20998/2074-272X.2016.1.10 
 
D.A. Gapon, Ya.S. Bederak 
 
GUARANTEEING THE TROUBLE-FREE OPERATION OF CAPACITOR BANKS 
IN POWER-SUPPLY SYSTEMS OF INDUSTRIAL ENTERPRISES 
 
Purpose. The problem of resonance phenomena in power systems of industrial enterprises using capacitor banks for reactive 
power compensation was detected. Circuit of the capacitor banks tier to downshift main substation tires is present. But there is no 
common algorithm to calculate and avoid such trouble. The main goal of this article is to introduce some basics for power supply 
systems with possible resonant circuits engineering. Methodology. At the first step the data on the change of the current in the 
chemical company network when changing capacitor banks value are received. For these purposes the oscilloscope function of 
digital protection relay was used. Current data samples were analyzed by spectrum detection software. Most significant levels of 
the 3rd and 5th harmonics were achieved. Comparison of harmonic distortion levels with and without capacitor bank is given. 
Results. Achieved data allow making conclusion about overloading reasons of capacitor banks while higher harmonics currents 
presence. A voltage and current harmonious composition measuring in the absence of power quality analyzers using digital 
protection relay terminals or emergencies registers are proposed. The necessity of power quality monitoring near capacitor banks 
connections to avoid resonance phenomena (current and voltage resonance) in industrial power supply systems is proven. The 
control algorithm of capacitor banks to provide electromagnetic compatibility, while various modes of nonlinear load operation is 
given. Originality. Using of digital protection relay oscilloscoping for current resonant detection can allow to significally reduce 
time and cost of solution. Replacement parallel circuit comprising a branch and one active-inductive load to another branch 
network in the presence of higher harmonics source are proposed. Practical value. A sequence for measuring the levels of 
harmonic components at the connections of capacitor banks in the absence of specialized instruments is proposed. The algorithm 
to avoid possible resonance currents in the presence of condensing units is proposed. References 9, tables 2, figures 2. 
Key words: power supply system, resonance, capacitor bank, power quality, electromagnetic compatibility. 
 
В статье рассматривается проблема резонансных явлений в системах электроснабжения промышленных 
предприятий, использующих конденсаторные установки для компенсации реактивной мощности. Приведены данные 
по изменению токов 3-й и 5-й гармонических составляющих в сети химического предприятия при изменении 
мощности присоединенных конденсаторных установок. Предложен способ измерения качества электроэнергии при 
отсутствии анализаторов. Разработан алгоритм обеспечения электромагнитной совместимости на 
присоединениях конденсаторных установок. Библ. 9, табл. 2, рис. 2. 
Ключевые слова: система электроснабжения, резонанс, конденсаторные установки, качество электрической энергии, 
электромагнитная совместимость. 
 
Problem definition. In some cases in power-supply 
systems of industrial enterprises dangerous resonant 
phenomena can arise. For example, at simultaneous 
utilization of the smooth soft start device which includes a 
semiconductor converter and a capacitor bank, the failure 
resonant currents able to destroy the capacitor bank as 
well as the whole power supply-system were fixed [1]. 
Generally, we can speak that the phenomenon of the 
current resonance is inherent for power-supply systems to 
which nonlinear customers and devices of reactive power 
compensation are connected simultaneously. Trends of 
the modern electrical customers’ development permit to 
speak that power and number of used semiconductor 
converters increase permanently. Devices of reactive 
power compensation including capacitor banks become 
more and more widely used. So, a task of the capacitor 
banks and, in general, power supply systems of industrial 
enterprises protection from resonant phenomena is actual. 
There is necessity to develop methods and techniques to 
improve electromagnetic compatibility of power supply 
systems of industrial enterprises. 
Analysis of last investigations and publications. In 
[2] it is noted that resonance arising on the substation’s 
buses results in sharp increase of the current, mainly by 
sharp increase of its harmonic components in the 
resonance circuit. In [3] it is determined that in the circuit 
including capacitor bank in one loop and active-inductive 
load in another one, voltage resonance in addition to 
current one can arise. A technique of the calculation of 
the resonant frequency in such a circuit is proposed in [4]. 
Ya.E. Shklyarskiy and A.N. Skamin have determined the 
dependence of the capacitor bank’s overload factor on 
compensating devices’ power, power of linear and 
nonlinear loads, spectra of current and voltage. Besides, 
assessment of the power grid’s parameters at various 
conditions of arising of higher harmonics which 
guarantees the capacitor bank operation without overload 
is presented [5]. 
The goal of the paper: to develop a methodology of 
measurement of harmonic components on capacitor 
banks’ connections and propose measures to prevent 
current resonance in power supply systems of industrial 
enterprises which include capacitor banks. 
Main research material. Operational regulations 
for exploitation of consumers’ electrical installations [6] 
recommend that on the medium voltage capacitor 
installations’ connections on-line monitoring of the 
electrical energy quality parameters should be carried out, 
and on the low voltage capacitor installations’ 
connections such measurements should be carried out 
periodically. To do it, it is necessary to use specialized 
analyzers of the electrical energy quality. A lot of world-
wide manufacturers develop and produce such devices. 
However, they are very expensive, so utilization of such 
devices in power supply systems of industrial enterprises 
requires huge expenses. High price of electrical energy 
quality analyzers is determined mainly by utilization of 
high-technological elementary base that is necessary to 
guarantee high requirements for the measurement’s 
 ISSN 2074-272X. Електротехніка і Електромеханіка. 2016. №1 57 
precision. However, the presence of the high accuracy is 
not principal to determine and analyze the resonance. So, 
in the case of the absence of specialized measurement 
devices it is possible to measure the voltage and current 
harmonic compositions by using microprocessor 
terminals of the relay protection or fault recorders which 
have the accuracy class 0.5 for current and voltage 
measurement. Mainly they have a function of the 
registration of current and voltage oscillograms at 
arbitrary time. However, it is necessary to note that some 
terminals of relay protection (for example, by Siemens) 
use preliminary signal processing by using an analog band 
filter to extract first harmonic. It is obvious that in this 
case information about presence and parameters of higher 
harmonics losses. Therefore, before the oscillograms 
registration it is necessary to be sure that the device is 
able to save necessary spectral components. Obtained data 
are converted in the COMTRADE format which is open 
and described in the free Standard permits to proceed 
information by using a wide spectra of computer codes. 
There are developments by Siemens, Aniger, Hartron, 
Uniti and other Companies. Most of codes permits to 
carry out computations of higher harmonic components of 
current and voltage.  
One-line diagrams of the capacitor bank 6 kV No. 1, 2 
are presented in Fig. 1, 2 respectively.  
 1 section 6 kV of main step-down substation №1
1 input on substation 1
1 input on substation 2
1 input on substation 3
1 input on substation 4
1 input on substation 5
capacitor bank 1/1 
1980 kVAr 
capacitor bank 1/2 
1980 kVAr  
Fig. 1. One-line diagram of the capacitor bank No. 1 connection 
to buses 6 kV of the main step-down substation of the industrial 
enterprise 
 2 section 6 kV of main step-down substation №1
2 input on substation 1
2 input on substation 2
2 input on substation 3
2 input on substation 4
2 input on substation 5
capacitor bank 2/1 
2640 kVAr 
capacitor bank 2/2 
1320 kVAr  
Fig. 2. One-line diagram of the capacitor bank No. 2 connection 
to buses 6 kV of the main step-down substation of the industrial 
enterprise 
 
Measurement was carried out on the capacitor 
bank’s connections of 6 kV which are used for the 
reactive power compensation on the bus section of the 
step-down substation at the chemical enterprise. In Tables 
1, 2 values on n-th harmonic components on buses of the 
capacitor banks No. 1, 2 are respectively presented. It is 
necessary to note that in both case amplitude of the 3rd 
voltage harmonic does not exceed 4%, and amplitude of 
the 5th harmonic component isles than 5% that is 
permissible in the correspondence with the Sate Standard 
GOST 13109 – 97 [7].  
 
Table 1 
Values of coefficients of the n-th current harmonic component 
in percent before and after the capacitor bank No. 1 connection 
After the capacitor unity 
connection 
(partial connection) 
After the capacitor unity 
connection 
(full) Harmonic 
No. Current of 
the phase 
А 
Current of 
the phase С 
Current of 
the phase А 
Current of 
the phase С 
3 0.7 0.41 0.74 0.44 
5 8.95 6.63 26.00 18.78 
 
Results of measurements prove that at the change of 
the connected capacitor bank’s power (see Table 1, 2) 
currents of higher harmonic components can arise 
essentially exceeding permissible normative values [8] 
resulting in the capacitor bank’s overload. In the same 
time load on connections can vary widely. Depending on 
the value of the inductive load the current resonance at the 
frequency of one or another current harmonic can arise. 
To prevent such situations it is necessary to change the 
capacitor bank’s connected capacity in such a way that 
the quiescent frequency of the oscillation circuit do not 
coincide with the frequency of one of any present higher 
harmonics. It is necessary to note that realization of such 
a adjustment requires huge investigations at the first stage 
of which it is necessary to collect a lot of information 
about resonant phenomena in power-supply systems of 
industrial enterprises. Therefore, there is an actual 
necessity to organize monitoring of the electrical energy 
quality on the capacitor bank’s connections. Proceeding 
of data collected in such a way will permit to guarantee in 
the future electromagnetic compatibility of capacitor 
banks independently on the composition and character of 
the network loading [9]. 
 
Table 2 
Values of coefficients of the n-th current harmonic component 
in percent before and after the capacitor bank No. 2 connection 
After the capacitor unity 
connection 
(partial connection) 
After the capacitor 
unity connection 
(full) Harmonic 
No. 
Current of 
the phase А 
Current of 
the phase 
С 
 Current of 
the phase 
А 
3 1.06 0.76 0.59 0.48 
5 13.7 10.65 8.9 2.29 
 
So, to prevent resonant phenomena on the capacitor 
banks’ connections the following sequence of actions is 
proposed: 
1. Measurement of parameters of electrical energy 
quality on the capacitor banks’ connections. 
1.1. Measurement of parameters of electrical energy 
quality on the capacitor banks’ disconnected connections 
(determination of the voltage harmonic set). 
 58 ISSN 2074-272X. Електротехніка і Електромеханіка. 2016. №1 
1.2. Measurement of parameters of electrical energy 
quality on each stage of the capacitor bank from minimal 
power to full power of the capacitor bank. 
2. Proceeding of the measurement results. 
Determination of the capacitor bank’s power at which 
there is essential increase of the coefficient of the n-th 
current harmonic component. 
3. Determination of sources of nonlinear distortions 
influencing on the electrical energy quality. 
4. Building an equivalent circuit of the parallel one 
which includes the capacitor unit in one loop and active-
inductive load in another one at presence a higher 
harmonics source in the network. 
5. Calculation of the resonance frequency and the pass 
band in the circuit. 
6. Decrease of the capacitor bank’s power at the 
coincide of the resonance frequency in the circuit with the 
frequency of odd higher harmonics divisible by 50 Hz. 
7. Check of the possibility of resonance phenomena 
arising in the mode of the nonlinear load start at presence 
of the higher harmonics source in the network that is 
connected for short time [1]. 
Conclusions. 
1. It is propose to measure the voltage and current 
harmonics set струму at the absence of electrical energy 
quality analyzers by using microprocessor relay 
protection terminals or by fault recorders. 
2. Necessity of organization of the electrical energy 
quality monitoring on the capacitor banks’ connections to 
prevent resonance phenomena (current and voltage 
resonance) in power-supply systems of industrial 
enterprises is proved. 
3. An algorithm to guarantee the electromagnetic 
compatibility on the capacitor banks’ connections which 
can work in the mode of the nonlinear load start as well as 
in the mode of steady operation of electrical load. 
 
REFERENCES 
1. Gapon D.A., Bederak Ya.S. Features of the operation 
regime of the mains during soft start of powerful synchronous 
motors. Promyshlennaia energetika – Industrial Power 
Engineering, 2014, no.2, pp.27-30 (Rus). 
 
2. Beliy V.B. Electromagnetic compatibility of power-supply 
systems’ elements comprising reactive power compensation 
devices. Vestnik Altaiskogo Gosudarstvennogo Agrarnogo 
Universiteta – Bulletin of the Altai State Agrarian University, 
2009, no.6, pp. 62-65 (Rus). 
3. Bederak Y.S., Oleynik S.V., Shuliak A.A. Research of 
capacitors mode 6 (10) kV connected to branches of dual 
limiting current reactor. Elektromekhanichni i enerhozberihaiuchi 
systemy – Electromechanical and energy saving systems, 2013, 
vol.2, part 2, pp. 290-294. (Ukr). 
4. Bederak Y.S. Electromagnetic compatibility of complex 
industrial power supply systems Visnyk NTU «KhPІ» – Bulletin 
of NTU «KhPІ», 2014, no.60, pp. 37-45. (Ukr).  
5. Shklyarskiy Ya.E., Skamin A.N. Industrial research into 
high harmonic influence on compensation devices. 
Elektrotekhnika i elektromekhanika – Electrical engineering & 
electromechanics, 2013, no.1, pp. 69-71 (Rus). 
6. Rules of technical operation of electrical consumers, 
approved by the Ministry of Fuel and Energy of Ukraine 
25.07.2006, no.258 (as amended by Order of the Ministry of 
Energy and Coal Industry of 13.02.2012 no.91) with 
amendments, approved by the Ministry of Energy and Coal 
Industry of Ukraine 11.16.2012 no.905. (Ukr). 
7. State Standard 13109-97. Electric Energy. Compatibility of 
technical equipment. Standards of quality of electric energy in 
power systems for general use. Interstate standard. Moscow, 
IPC Standards Publ., 1998. 31 p. (Rus). 
8. IEEE Standard 519-1992. IEEE recommended practices and 
requirements for harmonic control in electrical power systems. 
– 100 p.  
9. Bederak Y.S. Current and voltage monitoring 
implementation with varying load character in the branches of 
twin reactor in the presence of higher harmonics sources. 
Enerhetyka ta elektryfikatsiia – Energetic and electrification, 
2013, no.8, pp. 48-51 (Ukr). 
 
Received 09.10.2015 
 
D.A. Gapon1, Candidate of Technical Science, Associate Professor, 
Ya.S. Bederak2, Engineer, 
1 National Technical University «Kharkiv Polytechnic Institute», 
21, Frunze Str., Kharkiv, 61002, Ukraine. 
phone +38 057 7076551, e-mail: dima12345ml@mail.ru 
2 PJSC «AZOT», 
72, Pervomayskaya Str., Cherkassy, 18014, Ukraine. 
phone +38 047 2392979, e-mail: ei@uch.net 


Guaranteeing the trouble-free operation of capacitor banks in power-supply systems of industrial enterprises

Purpose. The problem of resonance phenomena in power systems of industrial enterprises using capacitor banks for reactive power compensation was detected. Circuit of the capacitor banks tier to downshift main substation tires is present. But there is no common algorithm to calculate and avoid such trouble. The main goal of this article is to introduce some basics for power supply systems with possible resonant circuits engineering. Methodology. At the first step the data on the change of the current in the chemical company network when changing capacitor banks value are received. For these purposes the oscilloscope function of digital protection relay was used. Current data samples were analyzed by spectrum detection software. Most significant levels of the 3rd and 5th harmonics were achieved. Comparison of harmonic distortion levels with and without capacitor bank is given. Results. Achieved data allow making conclusion about overloading reasons of capacitor banks while higher harmonics currents presence. A voltage and current harmonious composition measuring in the absence of power quality analyzers using digital protection relay terminals or emergencies registers are proposed. The necessity of power quality monitoring near capacitor banks connections to avoid resonance phenomena (current and voltage resonance) in industrial power supply systems is proven. The control algorithm of capacitor banks to provide electromagnetic compatibility, while various modes of nonlinear load operation is given. Originality. Using of digital protection relay oscilloscoping for current resonant detection can allow to significally reduce time and cost of solution. Replacement parallel circuit comprising a branch and one active-inductive load to another branch network in the presence of higher harmonics source are proposed. Practical value. A sequence for measuring the levels of harmonic components at the connections of capacitor banks in the absence of specialized instruments is proposed. The algorithm to avoid possible resonance currents in the presence of condensing units is proposed

D.A. Gapon

Ya.S. Bederak

Directory of Open Access Journals

Electrical Engineering & Electromechanics

GUARANTEEING THE TROUBLE-FREE OPERATION OF CAPACITOR BANKS IN POWER-SUPPLY SYSTEMS OF INDUSTRIAL ENTERPRISES

Purpose. The problem of resonance phenomena in power systems of industrial enterprises using capacitor banks for reactive
power compensation was detected. Circuit of the capacitor banks tier to downshift main substation tires is present. But there is no
common algorithm to calculate and avoid such trouble. The main goal of this article is to introduce some basics for power supply
systems with possible resonant circuits engineering. Methodology. At the first step the data on the change of the current in the
chemical company network when changing capacitor banks value are received. For these purposes the oscilloscope function of
digital protection relay was used. Current data samples were analyzed by spectrum detection software. Most significant levels of
the 3rd and 5th harmonics were achieved. Comparison of harmonic distortion levels with and without capacitor bank is given.
Results. Achieved data allow making conclusion about overloading reasons of capacitor banks while higher harmonics currents
presence. A voltage and current harmonious composition measuring in the absence of power quality analyzers using digital
protection relay terminals or emergencies registers are proposed. The necessity of power quality monitoring near capacitor banks
connections to avoid resonance phenomena (current and voltage resonance) in industrial power supply systems is proven. The
control algorithm of capacitor banks to provide electromagnetic compatibility, while various modes of nonlinear load operation is
given. Originality. Using of digital protection relay oscilloscoping for current resonant detection can allow to significally reduce
time and cost of solution. Replacement parallel circuit comprising a branch and one active-inductive load to another branch
network in the presence of higher harmonics source are proposed. Practical value. A sequence for measuring the levels of
harmonic components at the connections of capacitor banks in the absence of specialized instruments is proposed. The algorithm
to avoid possible resonance currents in the presence of condensing units is proposed.В статье рассматривается проблема резонансных явлений в системах электроснабжения промышленных
предприятий, использующих конденсаторные установки для компенсации реактивной мощности. Приведены данные
по изменению токов 3-й и 5-й гармонических составляющих в сети химического предприятия при изменении
мощности присоединенных конденсаторных установок. Предложен способ измерения качества электроэнергии при
отсутствии анализаторов. Разработан алгоритм обеспечения электромагнитной совместимости на
присоединениях конденсаторных установо

Gapon, D.A.

Bederak, Ya.S.

Наукова електронна бібліотека періодичних видань НАН України (Vernadsky National Library of Ukraine)

D. A. Gapon

Ya. S. Bederak

Crossref

eNTUKhPIIR Electronic National Technical University "Kharkiv Polytechnic Institute"; Institutional Repository

Електричні станції, мережі і системи  56  ISSN 2074-272X. Електротехніка і Електромеханіка. 2016. №1 © D.A. Gapon, Ya.S. Bederak UDC 621.311                                                                                                               doi: 10.20998/2074-272X.2016.1.10  D.A. Gapon, Ya.S. Bederak  GUARANTEEING THE TROUBLE-FREE OPERATION OF CAPACITOR BANKS IN POWER-SUPPLY SYSTEMS OF INDUSTRIAL ENTERPRISES  Purpose. The problem of resonance phenomena in power systems of industrial enterprises using capacitor banks for reactive power compensation was detected. Circuit of the capacitor banks tier to downshift main substation tires is present. But there is no common algorithm to calculate and avoid such trouble. The main goal of this article is to introduce some basics for power supply systems with possible resonant circuits engineering. Methodology. At the first step the data on the change of the current in the chemical company network when changing capacitor banks value are received. For these purposes the oscilloscope function of digital protection relay was used. Current data samples were analyzed by spectrum detection software. Most significant levels of the 3rd and 5th harmonics were achieved. Comparison of harmonic distortion levels with and without capacitor bank is given. Results. Achieved data allow making conclusion about overloading reasons of capacitor banks while higher harmonics currents presence. A voltage and current harmonious composition measuring in the absence of power quality analyzers using digital protection relay terminals or emergencies registers are proposed. The necessity of power quality monitoring near capacitor banks connections to avoid resonance phenomena (current and voltage resonance) in industrial power supply systems is proven. The control algorithm of capacitor banks to provide electromagnetic compatibility, while various modes of nonlinear load operation is given. Originality. Using of digital protection relay oscilloscoping for current resonant detection can allow to significally reduce time and cost of solution. Replacement parallel circuit comprising a branch and one active-inductive load to another branch network in the presence of higher harmonics source are proposed. Practical value. A sequence for measuring the levels of harmonic components at the connections of capacitor banks in the absence of specialized instruments is proposed. The algorithm to avoid possible resonance currents in the presence of condensing units is proposed. References 9, tables 2, figures 2. Key words: power supply system, resonance, capacitor bank, power quality, electromagnetic compatibility.  В статье рассматривается проблема резонансных явлений в системах электроснабжения промышленных предприятий, использующих конденсаторные установки для компенсации реактивной мощности. Приведены данные по изменению токов 3-й и 5-й гармонических составляющих в сети химического предприятия при изменении мощности присоединенных конденсаторных установок. Предложен способ измерения качества электроэнергии при отсутствии анализаторов. Разработан алгоритм обеспечения электромагнитной совместимости на присоединениях конденсаторных установок. Библ. 9, табл. 2, рис. 2. Ключевые слова: система электроснабжения, резонанс, конденсаторные установки, качество электрической энергии, электромагнитная совместимость.  Problem definition. In some cases in power-supply systems of industrial enterprises dangerous resonant phenomena can arise. For example, at simultaneous utilization of the smooth soft start device which includes a semiconductor converter and a capacitor bank, the failure resonant currents able to destroy the capacitor bank as well as the whole power supply-system were fixed [1]. Generally, we can speak that the phenomenon of the current resonance is inherent for power-supply systems to which nonlinear customers and devices of reactive power compensation are connected simultaneously. Trends of the modern electrical customers’ development permit to speak that power and number of used semiconductor converters increase permanently. Devices of reactive power compensation including capacitor banks become more and more widely used. So, a task of the capacitor banks and, in general, power supply systems of industrial enterprises protection from resonant phenomena is actual. There is necessity to develop methods and techniques to improve electromagnetic compatibility of power supply systems of industrial enterprises. Analysis of last investigations and publications. In [2] it is noted that resonance arising on the substation’s buses results in sharp increase of the current, mainly by sharp increase of its harmonic components in the resonance circuit. In [3] it is determined that in the circuit including capacitor bank in one loop and active-inductive load in another one, voltage resonance in addition to current one can arise. A technique of the calculation of the resonant frequency in such a circuit is proposed in [4]. Ya.E. Shklyarskiy and A.N. Skamin have determined the dependence of the capacitor bank’s overload factor on compensating devices’ power, power of linear and nonlinear loads, spectra of current and voltage. Besides, assessment of the power grid’s parameters at various conditions of arising of higher harmonics which guarantees the capacitor bank operation without overload is presented [5]. The goal of the paper: to develop a methodology of measurement of harmonic components on capacitor banks’ connections and propose measures to prevent current resonance in power supply systems of industrial enterprises which include capacitor banks. Main research material. Operational regulations for exploitation of consumers’ electrical installations [6] recommend that on the medium voltage capacitor installations’ connections on-line monitoring of the electrical energy quality parameters should be carried out, and on the low voltage capacitor installations’ connections such measurements should be carried out periodically. To do it, it is necessary to use specialized analyzers of the electrical energy quality. A lot of world-wide manufacturers develop and produce such devices. However, they are very expensive, so utilization of such devices in power supply systems of industrial enterprises requires huge expenses. High price of electrical energy quality analyzers is determined mainly by utilization of high-technological elementary base that is necessary to guarantee high requirements for the measurement’s  ISSN 2074-272X. Електротехніка і Електромеханіка. 2016. №1 57 precision. However, the presence of the high accuracy is not principal to determine and analyze the resonance. So, in the case of the absence of specialized measurement devices it is possible to measure the voltage and current harmonic compositions by using microprocessor terminals of the relay protection or fault recorders which have the accuracy class 0.5 for current and voltage measurement. Mainly they have a function of the registration of current and voltage oscillograms at arbitrary time. However, it is necessary to note that some terminals of relay protection (for example, by Siemens) use preliminary signal processing by using an analog band filter to extract first harmonic. It is obvious that in this case information about presence and parameters of higher harmonics losses. Therefore, before the oscillograms registration it is necessary to be sure that the device is able to save necessary spectral components. Obtained data are converted in the COMTRADE format which is open and described in the free Standard permits to proceed information by using a wide spectra of computer codes. There are developments by Siemens, Aniger, Hartron, Uniti and other Companies. Most of codes permits to carry out computations of higher harmonic components of current and voltage.  One-line diagrams of the capacitor bank 6 kV No. 1, 2 are presented in Fig. 1, 2 respectively.   1 section 6 kV of main step-down substation №11 input on substation 11 input on substation 21 input on substation 31 input on substation 41 input on substation 5capacitor bank 1/1 1980 kVAr capacitor bank 1/2 1980 kVAr  Fig. 1. One-line diagram of the capacitor bank No. 1 connection to buses 6 kV of the main step-down substation of the industrial enterprise  2 section 6 kV of main step-down substation №12 input on substation 12 input on substation 22 input on substation 32 input on substation 42 input on substation 5capacitor bank 2/1 2640 kVAr capacitor bank 2/2 1320 kVAr  Fig. 2. One-line diagram of the capacitor bank No. 2 connection to buses 6 kV of the main step-down substation of the industrial enterprise  Measurement was carried out on the capacitor bank’s connections of 6 kV which are used for the reactive power compensation on the bus section of the step-down substation at the chemical enterprise. In Tables 1, 2 values on n-th harmonic components on buses of the capacitor banks No. 1, 2 are respectively presented. It is necessary to note that in both case amplitude of the 3rd voltage harmonic does not exceed 4%, and amplitude of the 5th harmonic component isles than 5% that is permissible in the correspondence with the Sate Standard GOST 13109 – 97 [7].   Table 1 Values of coefficients of the n-th current harmonic component in percent before and after the capacitor bank No. 1 connection After the capacitor unity connection (partial connection) After the capacitor unity connection (full) Harmonic No. Current of the phase А Current of the phase С Current of the phase А Current of the phase С 3 0.7 0.41 0.74 0.44 5 8.95 6.63 26.00 18.78  Results of measurements prove that at the change of the connected capacitor bank’s power (see Table 1, 2) currents of higher harmonic components can arise essentially exceeding permissible normative values [8] resulting in the capacitor bank’s overload. In the same time load on connections can vary widely. Depending on the value of the inductive load the current resonance at the frequency of one or another current harmonic can arise. To prevent such situations it is necessary to change the capacitor bank’s connected capacity in such a way that the quiescent frequency of the oscillation circuit do not coincide with the frequency of one of any present higher harmonics. It is necessary to note that realization of such a adjustment requires huge investigations at the first stage of which it is necessary to collect a lot of information about resonant phenomena in power-supply systems of industrial enterprises. Therefore, there is an actual necessity to organize monitoring of the electrical energy quality on the capacitor bank’s connections. Proceeding of data collected in such a way will permit to guarantee in the future electromagnetic compatibility of capacitor banks independently on the composition and character of the network loading [9].  Table 2 Values of coefficients of the n-th current harmonic component in percent before and after the capacitor bank No. 2 connection After the capacitor unity connection (partial connection) After the capacitor unity connection (full) Harmonic No. Current of the phase А Current of the phase С  Current of the phase А 3 1.06 0.76 0.59 0.48 5 13.7 10.65 8.9 2.29  So, to prevent resonant phenomena on the capacitor banks’ connections the following sequence of actions is proposed: 1. Measurement of parameters of electrical energy quality on the capacitor banks’ connections. 1.1. Measurement of parameters of electrical energy quality on the capacitor banks’ disconnected connections (determination of the voltage harmonic set).  58 ISSN 2074-272X. Електротехніка і Електромеханіка. 2016. №1 1.2. Measurement of parameters of electrical energy quality on each stage of the capacitor bank from minimal power to full power of the capacitor bank. 2. Proceeding of the measurement results. Determination of the capacitor bank’s power at which there is essential increase of the coefficient of the n-th current harmonic component. 3. Determination of sources of nonlinear distortions influencing on the electrical energy quality. 4. Building an equivalent circuit of the parallel one which includes the capacitor unit in one loop and active-inductive load in another one at presence a higher harmonics source in the network. 5. Calculation of the resonance frequency and the pass band in the circuit. 6. Decrease of the capacitor bank’s power at the coincide of the resonance frequency in the circuit with the frequency of odd higher harmonics divisible by 50 Hz. 7. Check of the possibility of resonance phenomena arising in the mode of the nonlinear load start at presence of the higher harmonics source in the network that is connected for short time [1]. Conclusions. 1. It is propose to measure the voltage and current harmonics set струму at the absence of electrical energy quality analyzers by using microprocessor relay protection terminals or by fault recorders. 2. Necessity of organization of the electrical energy quality monitoring on the capacitor banks’ connections to prevent resonance phenomena (current and voltage resonance) in power-supply systems of industrial enterprises is proved. 3. An algorithm to guarantee the electromagnetic compatibility on the capacitor banks’ connections which can work in the mode of the nonlinear load start as well as in the mode of steady operation of electrical load.  REFERENCES 1. Gapon D.A., Bederak Ya.S. Features of the operation regime of the mains during soft start of powerful synchronous motors. Promyshlennaia energetika – Industrial Power Engineering, 2014, no.2, pp.27-30 (Rus).  2. Beliy V.B. Electromagnetic compatibility of power-supply systems’ elements comprising reactive power compensation devices. Vestnik Altaiskogo Gosudarstvennogo Agrarnogo Universiteta – Bulletin of the Altai State Agrarian University, 2009, no.6, pp. 62-65 (Rus). 3. Bederak Y.S., Oleynik S.V., Shuliak A.A. Research of capacitors mode 6 (10) kV connected to branches of dual limiting current reactor. Elektromekhanichni i enerhozberihaiuchi systemy – Electromechanical and energy saving systems, 2013, vol.2, part 2, pp. 290-294. (Ukr). 4. Bederak Y.S. Electromagnetic compatibility of complex industrial power supply systems Visnyk NTU «KhPІ» – Bulletin of NTU «KhPІ», 2014, no.60, pp. 37-45. (Ukr).  5. Shklyarskiy Ya.E., Skamin A.N. Industrial research into high harmonic influence on compensation devices. Elektrotekhnika i elektromekhanika – Electrical engineering & electromechanics, 2013, no.1, pp. 69-71 (Rus). 6. Rules of technical operation of electrical consumers, approved by the Ministry of Fuel and Energy of Ukraine 25.07.2006, no.258 (as amended by Order of the Ministry of Energy and Coal Industry of 13.02.2012 no.91) with amendments, approved by the Ministry of Energy and Coal Industry of Ukraine 11.16.2012 no.905. (Ukr). 7. State Standard 13109-97. Electric Energy. Compatibility of technical equipment. Standards of quality of electric energy in power systems for general use. Interstate standard. Moscow, IPC Standards Publ., 1998. 31 p. (Rus). 8. IEEE Standard 519-1992. IEEE recommended practices and requirements for harmonic control in electrical power systems. – 100 p.  9. Bederak Y.S. Current and voltage monitoring implementation with varying load character in the branches of twin reactor in the presence of higher harmonics sources. Enerhetyka ta elektryfikatsiia – Energetic and electrification, 2013, no.8, pp. 48-51 (Ukr).  Received 09.10.2015  D.A. Gapon1, Candidate of Technical Science, Associate Professor, Ya.S. Bederak2, Engineer, 1 National Technical University «Kharkiv Polytechnic Institute», 21, Frunze Str., Kharkiv, 61002, Ukraine. phone +38 057 7076551, e-mail: dima12345ml@mail.ru 2 PJSC «AZOT», 72, Pervomayskaya Str., Cherkassy, 18014, Ukraine. phone +38 047 2392979, e-mail: ei@uch.net 

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Guaranteeing the trouble-free operation of capacitor banks in power-supply systems of industrial enterprises

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