CC BY
12Sciences of Europe # 28, (2018)_61
10. Фальковский О.И. Техническая электроди- Электродинамика и распространение радиоволн. -намика. - М.: Связь», 1978 С. 117. М.: Советское радио, 1979. С 40.
11. Марков Г.Т., Петров Б.М., Грудинская Г.П.
TECHNICAL SCIENCES
INDUCED VOLTAGE MEASUREMENT METODS IN MUE RYAZAN CITY POWER DISTRIBUTION NETWORKS (RCPDN)
Vasilyeva T.N.,
Dr.Sci.Tech., prof.
Avanesyan M.A., senior lecturer Doronkin O.A.
postgraduate
Ryazan state radio engineering University.
ABSTRACT
This paper deals with induced voltage and its effects on the overhead transmission lines. Definition of induced voltage and its 3 constituent parts is given. Various measurement methods of induced voltage in different grounding networks are described, the most informative one is chosen and a comparative analysis of it is done.
Keywords: induced voltage, measurement methods, capacitive and inductive effect, overhead lines under induced voltage, transmission lines, grounded and ungrounded networks.
Introduction.
On demand of the municipal unitary enterprise "Ryazan City Power Distribution Networks" (MUE RCPDN), induced voltage lines are to be investigated. The company has provided a list of 39 lines, line names and electrical specifications. To carry out research on each item from the list it is necessary to find out which lines may fall under the definition "Overhead transmission line under induced voltage"
The analysis of this effect should start with the definition of this type of lines. According to the established standards_the overhead line (OL) under induced voltage is such a line and/or a communication overhead line (COL) which pass along the full length of the operating OL or its separate parts near the operating OL or close to the alternating current contact network of the electrified railway station, voltage of more than 25V being induced on the de-energized OL in different circuits of their grounding when the working current on the operating OL is the highest.
The lines with more than 25 V of induced voltage should be determined on the basis_of this definition.
What does the induced voltage represent and what are its distinguishing features?
Induced voltage is the potential difference between the conductive parts of electrical installations (overhead lines or electrical equipment of transforming substations ) and zero potential point resulting from the electromagnetic field effect of the operating equipment on the electricity generating plants located in close proximity to it.[1,2 ]
Induced voltage is characterized by 3 effect constituent parts:
1. Capacitive effect. This is the effect which facilitates electric charge generation in the de-energized OL being repaired due to the OL electric charge effect under operating voltage. This impact is completely lost
after the de-energized line is earthed at least at one point under weak resistance.
2. Conductive effect. This type of effect occurs on the de-energized OL in case of a wire break of the operating OL crossing the de-energized OL at the point of their contact. Being quite uncommon, this affect is the most dangerous one if contacting the grounded support and machinery under high voltage.
3. Inductive effect. It occurs on the de-energized OL of a longitudinal electromotive force (emf) under the impact of the alternating magnetic field of the operating OL. Transverse capacitive_and active resistance available causes "wire-ground" voltage. Inductive effect occurs on the ungrounded as well as ungrounded de-energized OL.
Thus, it is the inductive effect which produces voltage on the OL in any grounded circuits without de-energized OL wires being earthed.
Figure 1 shows inductive effect diagrams on the de-energized OL with AB length.
Graphs a) and b) show induced voltage distribution on the ungrounded OL or grounded at the ends respectively, graphs c) and d) - when the line is grounded
at one end, graphs f) and e) - when the line is earthed at one or more points along this line.
When the number of grounding points on the OL changes, it is zero potential point position which changes on it. It is this particular feature that industrial safety rules (ISR) are determined by.
What risks does induced voltage involve?
This effect, though being uncommon, is considered to be more dangerous in comparison with running voltage as safety devices fail to react against it. If an employee dealing with this problem gets under induced voltage, he will remain affected until he gets free from it by himself or is evacuated. Under the running voltage impact, safety devices work well enough and electricity is switched off.
Consequences of induced voltage effect for a person are rather serious: life-threatening burning injury sometimes even with fatal outcome. That's why, it is very important to observe safety rules while working on the de-energized power lines.
In preparation for a workplace on the overhead line, contact reliability of protective grounding with phase wires and grounding electrodes should be paid particular attention to. It is necessary to bear in mind that in case of accidental contact loss (ungrounded line), zero potential point may immediately change its position and the voltage at the workplace may exceed the allowed value. Therefore, to ensure safety at the workplace it is advisable to install two grounding electrodes in parallel.
Figure 2 shows the voltage at the workplace when the line is ungrounded.
The purpose of this study is to find_the safest and most informative measurement method of induced voltage in the networks which are served by MUE RCPDN.
Work tasks.
1. To select induced voltage measuring techniques for 10/0,38 KV networks
2. To choose induced voltage measuring devices for 10/0,38KV networks
3. To make clear procedural instructions on induced voltage measurement in 10/038KV network served by RCPDN
Theoretical considerations.
Induced voltage measurement must be performed at the points where induced voltage values are the highest, namely:
-at the beginning and the end of the overhead line; -at the division points of the double-circuit overhead lines into single-circuit ones;
-at the points where overhead lines change their position towards each other;
-at the transposition points of the de-energized or induced OL (fig.3).
Umax Umax Umax Umax
Figure 3 shows induced voltage maximum values.
At the moment there are no clear instructions in the established standards how to measure the induced voltage. Besides, the definition "Induced Voltage lines" contains some inaccuracy in particular in the part "in different networks of their grounding". Therefore, it is the engineering personnel of the enterprises who is responsible for making measurement procedural instructions as well as doing preliminary calculations.
There are different ways of defining induced voltage, [1-4] Consider two most popular ones widely used in electrical networks.
According to one of them measurements of induced voltage on de-energized OL are carried out in a usual mode of working line operation when power transmission is at its peak.
When the de-energized OL and COL are passing near some working lines, the main effect on the induced voltage values is generally exerted by the lines which are the nearest to the de-energized OL and COL, and in some cases by more distant lines having the highest load. [2, 4] Before measuring the overhead line, which is intended to be measured, must be de-energized and
grounded at the ends (in a switchgear-SWG) At the points of disconnection all the three OL phases must be earthed. In general, measurements on the de-energized OL are performed when all the three phases at the measuring points are simultaneously earthed, total portable grounding at the measuring points being connected to one and the same earth electrode. (fig.4)
Figure 4.
Induced voltage is calculated by the following for-
mula:
U
— u x
i.meas
I
h.o.
I
(1)
t.o.
where - U .meas. - measured induced voltage, V; Ih.o. the highest current of the operating OL, A; ho. - current of the operating OL at the time of measurement, A.
This method is difficult to use because it requires a more accurate definition of the impact of two or more induced lines as well as a more clear definition of induced voltage in each phase conductor. Besides, this method does not guarantee the required level of safety since, when the contact between the grounding conductor and the earth is broken, a strong current up to dozens kA is generated at the moment of measuring.
Consider another measuring method of induced voltage in different grounding networks [2, 3, 4].
OL is de-energized and grounded, portable grounding at workplace is installed (for safety purpose in preparation for a workplace), a switch and measuring devices are installed on the dielectric mat at the distance of 20 meters from the footing and other grounding devices, a measuring electrode is embedded into the ground, a network is set up.(fig.5)
Figure 5 shows induced voltage measurement in different grounding networks.
At the end of the measurement the maximum induced voltage value Ui.meas is calculated under the highest working current of the operating OL.
Grounded test leads are connected to the OL wires, portable grounding installed at the workplace is switched-off, with the help of an insulated rod and a switch test leads grounding is de-energized and their alternate connection to measuring devices is established. The circuit with the highest induced voltage values is chosen from a number of grounded and ungrounded wires and measuring device connections.
To determine the induced voltage value under different OL grounded and ungrounded networks the following mode of operation is established:
1. Grounding is disconnected in the second switchgear (SWG) and the induced voltage measurement is made according to the ungrounded circuit in the second SWG;
2. Grounding is disconnected in the first SWG and measurements on the ungrounded overhead line is made with a kilovolt-meter;
3. Grounding in the first SWG is connected, induced voltage measurements are performed according to the ungrounded circuit in the second SWG;
Measurements on the overhead lines having more than two SWG are carried out in the same way.
U
— u X
i.meas
I
h.o.
I
(2)
t .o.
where - Ui .meas. - measured induced voltage, V; h.o.- the highest current of the operating OL, A; ho - current of the operating OL at the time of measurement, A.
On passing the overhead line along some operating OL passageways:
I
U
— U
X
X ho.
I
Xto.
(3)
where - Ish.o. is the sum of the maximum possible current values passing along the operating OL, A. which is calculated by the formula:
L
I h.
n
= ILA . o.
(4)
i=1
where - ht.o. is the sum of the maximum possible measured current values passing along the operating OL, A. which is calculated by the formula:
L
I
t .o.
n
Ilto.
(5)
i=1
Induced voltage measurement system (IVMS) and induced voltage meter (IVM-15) made in Russia may be used as a measuring device (fig.6 ) It is designed to measure root-mean-square values of alternating voltage with industrial frequency of 50 Hz generated on the de-energized towards the earth sections of electricity generating plants to guarantee personnel safety involved in overhead line operation.
This device represents a two-terminal network one of which is a probe with induced voltage meter (IVM-15) and the other is a contacting wire with a clamp fixed to the grounding electrode.
To measure the induced voltage the second method will be used as it is more informative and meets safety requirements during the measurements.
Figure 6 shows induced voltage measurement system with IVM-15.
The research given will be helpful when making a procedural instructions for the RCPDN personnel involved in the field of electrical engineering.
References
1. Bessonov L.A. Theoretical basis of electrical engineering: Electrical circuits: Textbook for students of electrical, power-engineering, instrumentation-technology specialties. -7th edition, revised and supplemented - M.; Higher School, 2008 - 258p.
2. Organization standard "FGC UES": "Procedural instructions on induced voltage definition on disconnected overhead lines located near active overhead lines." M: OL - Spetsenergo, 2009, - 27p.
3. Inter-branch labor protection (safety rules) in electrical installation maintenance « 153-34.0-03.15000», - Moscow: STOCK COMPANY "NC ENAS PUBLISHERS", 2003. - 180p.
4. Tselebrovsky U. "Safety of works on overheard lines under induced voltage" I&R edition "Electrical Engineering News" NSTU
http://www.news.elteh.ru/arh/2008/51/07.php -
2018
DEVELOPMENT MICROPROCESSOR DEVICE MEASURING POWER FOR COMPUTER SYSTEMS MEASURE THE DISTANCE
Dudnik A.S.
Candidate of technical sciences, associate professor Associate Professor of the Department of Network and Internet Technologies
Kyiv National Taras Shevchenko University
ABSTRACT
At the moment, wireless sensor networks are an important tool for researching the physical world. Their importance is connected with new possibilities of use, due to such characteristics of the BSM, as the lack of the need for cable infrastructure, miniature nodes, low power consumption, built-in radio interface, high enough computing power, relatively low cost. All this made possible their widespread use in many spheres of human activity in order to automate the processes of information gathering, monitoring, control over the characteristics of various technical and natural objects. At the same time due to the limited resources of individual nodes for solving many problems, the cooperative work of all nodes of the network is necessary for the achievement of the goal. One of these tasks is the task of locating nodes in a wireless sensor network with self-organization. It consists in determining the coordinates of individual sensors without the use of external infrastructure. The problem of localization has been researched in the past, as in many applications, information about the location of objects or people is important, and a large number of systems have been developed to address them. The most famous of them is the Global Positioning System (GPS). However, the GPS approach can not be applied to the BSM in connection with its requirements for the availability of a large number of additional infrastructure (for example, satellites). In this
