CC BY
2УДК 621.75 Mufidzade N.A., Aliyev I.H.
Mufidzade N.A.
Azerbaijan State Oil and Industry University (Baku, Azerbaijan)
Aliyev I.H.
Azerbaijan State Oil and Industry University (Baku, Azerbaijan)
INVESTIGATION OF OPERATIONAL MODES OF NEUTRAL IN ELECTRICAL NETWORKS
Аннотация: the article examines the influence of asymmetry on the magnitude of the current through the human body using computer models of an autonomous power supply system with voltage up to 1000 V with an insulated neutral made in software environment "Matlab-Simulink". The results of the study on a computer model the results of modeling are presented when a person touches phase A and the asymmetry in the network changes from 0 up to 10% (maximum permissible value of asymmetry) which confirms the influence of asymmetry on the value current through the resistance of the human body.
Ключевые слова: autonomous power supply system, computer model, 4-wire network, isolated neutral.
ASE dens with power up to 10 kW and over 10 to 100 kW. The rationale for these proposals is also given here. If in an ASE with a power of up to 10 kW, it is recommended that the power supply circuit be carried out using two-wire lines with
wires isolated from the ground, since in such systems, as consumers of electrical energy single-phase power receivers will be used [2], then in ASE with a power of up to 100 kW the presence of three-phase consumers is possible. Earlier Semenova M.N. [3] justification was given for the transfer of three-phase 4-wire networks from solidly grounded neutral mode to isolated. However, this proposal
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concerned rural electric networks with voltages up to 1000 V, the power of supply transformers in which is 160 kVA or more. Note also that in these networks there are qualified electrical personnel who are not entrusted with not only their operation, but also their maintenance. The scope of application of ASE with a power from 10 to 100 kW is currently extensive. They can be used in the following cases:
- in the absence of centralized power supply,
- in the absence of the possibility of connecting to a centralized power supply
system,
- remote objects,
- dachas, small houses, trade tents,
- remote warehouses, cabins, houses at recreation centers,
- for power supply of remote video surveillance and communications,
- for powering fire and security alarm systems,
Basically, such systems are used to provide electricity to private households,
farms
farms such as apiaries, cheese factories, greenhouses and greenhouses [4], [5], [6]. As a power source the most Photovoltaic (solar) batteries and wind power plants are in wide demand. It is not economically feasible to include an energy service in the structure of such enterprises. On In our opinion, such ASEs should be designed and executed in such a way that the value individual risk of electric shock was less than acceptable, i.e. less than 10-6. We will assess the risk of electric shock using the computer system we have developed. model described in [8]. A computer model of the electrical network was developed in the MATLAB software package using Simulink extensions and the SimPowerSistems library, the blocks of which model specific devices: sources energy, transformers, power lines and other equipment. The created computer model allows simulate electrical network modes that are difficult to organize in a real network. The computer model includes the parameters of a 4-wire network with an isolated neutral and power power supply 100 kVA. Proposed computer model of the network makes it possible to study the influence of the following factors upon human touch to one of the phases:
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- the influence of the network neutral mode on the magnitude of the current through the human body,
- influence of network phase insulation parameters on the magnitude of current through the human body,
- the influence of asymmetry in the network on the amount of current through the human body,
Table 1. The influence of asymmetry on the magnitude of the current through the
resistance of the human body.
I'm in Network asymmetry (%)
phase A 0 2.5 5 7(5 ID
Unbalan 2.6 279 2,79 23 23
ced UA 5.43 5,44 5,*5 S.47
and I IV3 241 5 243 243 243 243
in phase A UlB 241 5 237,2 237.2 П»|Ч А ¿3.-.2 237,3
Ur в 241.5 »4 Я2 245,2 245.2 245.2
Unbalan 2,8 2,bD 2,® 1, и
ced Lu, A. 5.43 5.44 j,-5 Е.47
and 1 IL В 241 5 2^2 245.2 245,2 245,2
on phase 8 1Л.В 241 S 243 243 2ЛЗ 243
Ut. Б 241,5 237,2 237,: ¿37,2 237,2
Unbalan киЛ 2.6 2,5В 2,58 2,1 8 2,sa
ced LA 5.13 5, G уз S,ИЗ
and 1 и,.з 241 5 237,2 237,2 23",2 237,2
in phase C и, Ь 241 Ь 24ïv 245,2
UtB 141.Z 2U 2А2 2л2 2ЛЭ
Conclusion. Using a computer model, the following values were obtained: I h - current flowing through the human body, In.p. - current flowing in the neutral wire and UA, UB, UC - voltages on phases A, B, C. From the table 1 shows that with increasing asymmetry in the network, the current through the human body increases. The highest the values of Ih are obtained when a person touches the phase at which the asymmetry is modeled (in our In this case, this is phase A). With an unbalance of 10%, the current through the human body has a numerical value equal to 2.8 mA.
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