Since the total capacity of the accident security load of the desulfurization system is not large, the capacity of the largest electric motor often exceeds 20 of the rated capacity of the diesel generator, so it is necessary to install a soft starter on the largest electric motor to limit the starting current and avoid excessive selection of the capacity of the diesel generator set.
For wet desulfurization, a desulfurization absorption tower is installed on the desulfurization island, so it is necessary to consider the lightning protection of the absorption tower. If the desulfurization island is arranged near the chimney of the main plant, you can first check whether the absorption tower is within the protection range of the chimney, otherwise, set the lightning rod at the top of the absorption tower to avoid repeated setting.
For the scheme of setting up desulfurization pressure working transformer, since the desulfurization transformer is arranged outside the human column, the desulfurization pressure distribution device is generally arranged in the desulfurization island, and the power supply distance is relatively long, so it is appropriate to use cable for power supply. Due to the long length of the cable, taking into account the cable failure to avoid the unit shutdown, it is recommended to set up protection equipment between the cable and the desulfurization transformer, that is, install a vacuum circuit breaker.
Conclusion Due to the rapid development of flue gas desulfurization, desulfurization methods are constantly improving. For different desulfurization process systems, the electrical system design should not only meet the requirements of the existing regulations and standards, but also combine the characteristics of the desulfurization system to design. The above design experience is only a comprehensive hospital in recent years to do the desulfurization project experience, for your reference.
Office of the Engineer. He has served as the main electrical equipment of Hangzhou Union Coal Transformation Flue Gas Desulfurization Project, the main electrical equipment of Anshun Power Plant Phase Project Flue Gas Desulfurization, the main electrical equipment of Anshun Power Plant Phase 2300,07 and Baihe Power Plant Phase 23, Bay Project. Contact Address Chengdu Dongfeng Road 18 Southwest Electric Power Design Institute Postal Code 610021 Contact Phone Lighting Engineering Power Supply Design Several Questions Yong Jing of Chongqing University's School of Electrical Engineering Attended Several Questions, such as Power Supply Radius, Wiring Type, Protection Method, Overvoltage Protection, etc. And put forward the solution through analysis.
With the rapid development of the national economy, major cities across the country have invested heavily in lighting projects. Chongqing night scene is also known as the city's business card for lighting projects. However, due to the particularity of its use function, the power supply system of lighting projects has some problems different from those of conventional building power supply design, which are proposed to be discussed with colleagues.
1 Characteristics and 1.1 of power supply system for lighting engineering Power supply lines and power distribution equipment for lighting engineering are located outdoors, which are greatly affected by temperature difference between year and season and wind and sun, and are vulnerable to lightning strikes, resulting in relatively harsh operating environment. The design should pay attention to the leakage protection question; lightning protection question; distribution system ground fault protection question, etc.
In 1.2 lighting engineering, the use of lamps is large and the distribution range is wide. Design should pay attention to select the appropriate power supply radius; appropriate leakage protection action current.
1.3 lighting engineering lighting source generally uses gas discharge light source, the starting current is large, the starting time is long, and sometimes there is a strong harmonic generation. Design should pay attention to the choice of protection characteristics of electrical protection.
The determination of 2.1 power supply radius The power supply radius is directly related to the configuration of power transformation and distribution stations. The power supply radius should not only meet the requirements of voltage loss, but also meet the requirements of single-phase short-circuit protection sensitivity and grounding fault action time. Taking poly-ethylene insulated electric system lines as an example, it is assumed that the current flowing on the lines is 90% of the rated current carrying capacity of the lines, the setting current 1 of the protection long-delay tripping device is 90 of the rated current carrying capacity of the line, and the setting current of the instantaneous tripping device is 5 out, which meets the condition of line voltage loss 10, meets the condition of single-phase short-circuit protection sensitivity at the end of the line, meets the condition of grounding fault action time 53, such as 1. Since the line section directly supplying power to lighting equipment should not be too large, only the calculation results of 35 stomach 2 and below are listed; the operation characteristics of the 045 short-circuit device are taken as an example in the calculation. Assuming that the 101 side of the transformer is an infinite large-capacity system, the transformer is taken as an example by the 6301, and the calculation results are not different when the transformer capacity is different.
Meet the voltage plug-in single-phase, road protector sensitivity grounding, action time requirements of the power supply radius electrical winding section un2 protection radius meet the voltage loss requirements meet the single-phase short circuit protectionIt can be seen that the power supply radius meeting the sensitivity requirement of single-phase short-circuit protection is the smallest, only more than 100 meters, I .e. the distance between power transformation and distribution stations should not exceed 300 meters, which is obviously not easy to meet. Therefore, the line cross-section must be increased to ensure that the sensitivity requirements of single-phase short-circuit protection are met. However, in fact, when the line is very long, the single-phase short-circuit current is very small, which is only equivalent to an overload current for the system. There is no need to require protection of instantaneous action. If only 53 actions are required, the power supply radius can be greatly increased.
Due to the poor operating environment, the cable with higher insulation strength should be selected as the distribution line. In addition, considering the power supply radius requirements, the cross-section selection is more appropriate between 1035mn12. This distribution radius of up to 250 m420m.
2.3.1 In order to ensure the safety of use when selecting the 15-wire system, leakage protection devices shall be provided in each circuit. The calculation method of leakage action current is as follows: 70mAkm;VV5X25 is laid 70mAkm through the tube; W5X16 is laid 62mAkm through the tube; VV5X10 is laid through the tube 56 and is called 2 fluorescent lamp metal frame to install each set of 0.1mA; Leakage data of high-strength gas discharge lamp is unknown.
Take the 535 circuit as an example. If the power distribution distance is 400 and 300 sets of 2361 fluorescent lamps are connected to the circuit to ensure that the leakage protection device of the power distribution line does not operate by mistake, the leakage protection action current 1 of the leakage protector shall be therefore, a leakage protector with a large action current 300 shall be set separately for each circuit, and no leakage protector shall be shared by several circuits.
As we all know, when the first phase grounding fault occurs in the ding system, the fault current is the vector sum of the other two opposite capacitance currents. the fault current is very small and does not constitute harm to human body. the power supply may not be interrupted to improve the reliability of power supply, and leakage protection is not required. However, an insulation monitor should be installed in the system to detect and eliminate the fault in time to avoid the first phase grounding fault.
Ting system should not be equipped with neutral line, otherwise when the neutral line insulation is damaged, the insulation monitor cannot detect the fault, and the ding system will become system operation at this time, and it is very dangerous without leakage protection.
Therefore, when a special transformer is set up for a lighting project, 100.23kV transformer can be considered, and the neutral point is insulated to ground, so that leakage protection equipment can be omitted.
Selection of protection characteristics of automatic air switch in 2.4 circuit 2.4.1 Since gas discharge light sources are commonly used in lighting engineering lighting sources, especially high-intensity gas discharge lamps, which have large starting current and long starting time, in order to avoid misoperation of automatic air switch, the protection characteristics should be selected as switches with large instantaneous operating current multiples and can avoid starting current.
2.4.2 Lighting engineering lighting has a strong simultaneity, in order to avoid overload when the transformer is started, it should be started by sub-loop.
2.4.3 lighting engineering due to some harmonic heavy light source and the use of switching power supply in the control circuit, in order to avoid the 3 system neutral line overload, neutral line with automatic air switch overload protection should be used.
The lines and equipment of the over-voltage protection lighting project are installed outdoors to prevent the insulation damage of the transformer caused by the transmission of atmospheric over-voltage along the line to the substation, and the lightning arrester shall be set at the distribution box for over-voltage protection.
3 Conclusion To sum up, due to the particularity of lighting power distribution in lighting engineering, sufficient attention should be paid to the following aspects when designing the system; 3.1 power supply linesCable runs shall be used with a cross section between 1035 mm2.
The 3.2 power supply radius shall be limited to 250m420rn according to the size of the cable section used in order to meet the requirements of ground fault protection and voltage loss. [br] When the 3.3 adopts 15 wiring type, the operating current shall be determined according to calculation, and a separate leakage protector shall be provided for each circuit.
3.4 For the power transformation and distribution system dedicated to the lighting project, the wiring type can be considered, using 100.23kV neutral point insulation transformer.
Switches for 3.5 circuit protection shall be automatic air switches with neutral overload protection.
3.6 The distribution box near the transformer shall be equipped with lightning arrester for over voltage protection.
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