中压开关柜中内部电弧故障的仿真与实验
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[1,3]
t = 0 = T0
Molar gas constant Volume of the compartment Gas mass inside the compartment Arc power Specific heat of the gas at constant volume Fraction of Pel leading to pressure rise, or coefficient of energy conversion
1
Introduction
The safety of the MV metal-enclosed switchgear
pressure and temperature inside the switchgear can not only enhance the safety of products, but also can save a great deal of test fee, shorten the period of development of new products, and the computation results can be used as the guide basis for improvement of existing products and development of new products. The investigations on arc faults have been done much in the world[1 6], but not so in China[7,8]. We have established the mathematical model for computation of pressure and temperature rise inside the enclosure after the arc faults occur on the basis of standard computation method, and software for calculation has been worked out. A metal-enclosed enclosure to simulate the bus compartment of MV switchgear has been made for the purpose of verifying the validity of computation results. A series of arc initiation tests on it have been done by using a pressure sensor to measure the pressure rise inside the enclosure. The effect on the pressure rise from some factors such as fault currents and the size of pressure relief vents were investigated. The computed results were compared with measured ones and both agreed well.
to the equipment and fatal injury to personnel. To simulate the fault arcs based on appropriate calculation methods can not only shorten the development period of arc resistant switchgear, but also save the development cost. The mathematical model to simulate and compute the pressure rise due to the internal arcing fault is described in this paper. The effects on pressure rise resulting from some factors such as fault currents and the size of pressure release vents are investigated via a test model and tests. The results of computation and of measurement during the tests are compared and agreed well. Therefore, this simulation software is helpful to the design of new arc-resistant switchgears. For instance, if the mechanical strength of an enclosure is known by test or by calculation using FEM software such as ANSYS, then the minimum area of the pressure relief vent or the maximum fault current which the enclosure could withstand can be achieved by using our simulation software with short calculation time. The method is also described in this paper. Keywords: Numerical simulation, metal-enclosed switchgear, internal arcing faults
p T where R V m P el cv kp
t=0 =
p 0 = 1.013×10 5 Pa = 293 K
and money, an appropriate computation method becomes an important tool to evaluate the effect of internal arc faults. Unfortunately, as stated above, internal arcing faults are complicated phenomena, and the knowledge on thermodynamics, hydrodynamics, gas dynamics, numerical analysis and simulation, computer, electrics and mechanics etc. should be concerned. Currently, there are mainly standard computation method, improved computation n method, CFD computation method[1] and ray-tracing computation method
Received October 9, 2003; in revised form December 12, 2003
万方数据
第 19 卷第 3 期
蔡
彬等
中压开关柜中内部电弧故障的仿真与实验
83
2
Computation Method
Because internal fault test spends too much time
Fra Baidu bibliotek
(2) After the pressure relief vent is opened The gas flow through the pressure relief hole shall be taken into account. The velocity of the gas flow through the hole is assumed to be homogeneous. The gas mass dm transferred from the compartment in a time interval d t is given by[1,6] dm = α ⋅ S ⋅ ρ n ⋅ υ n ⋅ dt adiabatic gas flow, p and T are given by dp k p ⋅ R ⋅ Pel α ⋅ S ⋅ k ⋅ p ⋅ RT = − ⋅Ψ dt c v ⋅V V dT k p ⋅ R ⋅ T ⋅ Pel α ⋅ S ⋅ (k + 1) ⋅ T ⋅ RT = − ⋅Ψ dt c v ⋅ p ⋅V V Primary condition is p T
2004 年 3 月 第 19 卷第 3 期
电 工 技 术 学 报
TRANSACTIONS OF CHINA ELECTROTECHNICAL SOCIETY
Vol.19 Mar.
No.3 2004
Simulation and Experiments on Internal Arcing Faults in MV Metal-clad Switchgear
Cai Bin Xi’an Abstract Cheng Degui Li Zhipeng 710049 China Jiaotong University Xi’an
The internal arcing faults in the metal-enclosed switchgear may cause serious damage
is more and more regarded by users and manufacturers because of its importance to the power distribution systems. Some causes, such as insulation aging, mal-operation, insufficient maintenance, ingress of foreign bodies (e.g. small animals, tools, organic residues.) and small ground fault, will initiate internal arc inside the switchgear, therefore, the pressure and temperature inside switchgear will rise rapidly due to the energy transfer from arc, the power supply will be interrupted, the personnel can be injured or killed and the equipment destroyed. Internal arcing fault is a complicated phenomenon with various physical and chemical effects such as intense light, sound, electric, and thermal effects. In order to prevent the internal fault, it’s necessary to make clear its course and mechanism. To establish the mathematical model for simulation and analysis of
t = 0 = T0
Molar gas constant Volume of the compartment Gas mass inside the compartment Arc power Specific heat of the gas at constant volume Fraction of Pel leading to pressure rise, or coefficient of energy conversion
1
Introduction
The safety of the MV metal-enclosed switchgear
pressure and temperature inside the switchgear can not only enhance the safety of products, but also can save a great deal of test fee, shorten the period of development of new products, and the computation results can be used as the guide basis for improvement of existing products and development of new products. The investigations on arc faults have been done much in the world[1 6], but not so in China[7,8]. We have established the mathematical model for computation of pressure and temperature rise inside the enclosure after the arc faults occur on the basis of standard computation method, and software for calculation has been worked out. A metal-enclosed enclosure to simulate the bus compartment of MV switchgear has been made for the purpose of verifying the validity of computation results. A series of arc initiation tests on it have been done by using a pressure sensor to measure the pressure rise inside the enclosure. The effect on the pressure rise from some factors such as fault currents and the size of pressure relief vents were investigated. The computed results were compared with measured ones and both agreed well.
to the equipment and fatal injury to personnel. To simulate the fault arcs based on appropriate calculation methods can not only shorten the development period of arc resistant switchgear, but also save the development cost. The mathematical model to simulate and compute the pressure rise due to the internal arcing fault is described in this paper. The effects on pressure rise resulting from some factors such as fault currents and the size of pressure release vents are investigated via a test model and tests. The results of computation and of measurement during the tests are compared and agreed well. Therefore, this simulation software is helpful to the design of new arc-resistant switchgears. For instance, if the mechanical strength of an enclosure is known by test or by calculation using FEM software such as ANSYS, then the minimum area of the pressure relief vent or the maximum fault current which the enclosure could withstand can be achieved by using our simulation software with short calculation time. The method is also described in this paper. Keywords: Numerical simulation, metal-enclosed switchgear, internal arcing faults
p T where R V m P el cv kp
t=0 =
p 0 = 1.013×10 5 Pa = 293 K
and money, an appropriate computation method becomes an important tool to evaluate the effect of internal arc faults. Unfortunately, as stated above, internal arcing faults are complicated phenomena, and the knowledge on thermodynamics, hydrodynamics, gas dynamics, numerical analysis and simulation, computer, electrics and mechanics etc. should be concerned. Currently, there are mainly standard computation method, improved computation n method, CFD computation method[1] and ray-tracing computation method
Received October 9, 2003; in revised form December 12, 2003
万方数据
第 19 卷第 3 期
蔡
彬等
中压开关柜中内部电弧故障的仿真与实验
83
2
Computation Method
Because internal fault test spends too much time
Fra Baidu bibliotek
(2) After the pressure relief vent is opened The gas flow through the pressure relief hole shall be taken into account. The velocity of the gas flow through the hole is assumed to be homogeneous. The gas mass dm transferred from the compartment in a time interval d t is given by[1,6] dm = α ⋅ S ⋅ ρ n ⋅ υ n ⋅ dt adiabatic gas flow, p and T are given by dp k p ⋅ R ⋅ Pel α ⋅ S ⋅ k ⋅ p ⋅ RT = − ⋅Ψ dt c v ⋅V V dT k p ⋅ R ⋅ T ⋅ Pel α ⋅ S ⋅ (k + 1) ⋅ T ⋅ RT = − ⋅Ψ dt c v ⋅ p ⋅V V Primary condition is p T
2004 年 3 月 第 19 卷第 3 期
电 工 技 术 学 报
TRANSACTIONS OF CHINA ELECTROTECHNICAL SOCIETY
Vol.19 Mar.
No.3 2004
Simulation and Experiments on Internal Arcing Faults in MV Metal-clad Switchgear
Cai Bin Xi’an Abstract Cheng Degui Li Zhipeng 710049 China Jiaotong University Xi’an
The internal arcing faults in the metal-enclosed switchgear may cause serious damage
is more and more regarded by users and manufacturers because of its importance to the power distribution systems. Some causes, such as insulation aging, mal-operation, insufficient maintenance, ingress of foreign bodies (e.g. small animals, tools, organic residues.) and small ground fault, will initiate internal arc inside the switchgear, therefore, the pressure and temperature inside switchgear will rise rapidly due to the energy transfer from arc, the power supply will be interrupted, the personnel can be injured or killed and the equipment destroyed. Internal arcing fault is a complicated phenomenon with various physical and chemical effects such as intense light, sound, electric, and thermal effects. In order to prevent the internal fault, it’s necessary to make clear its course and mechanism. To establish the mathematical model for simulation and analysis of