随着国民经济的平稳较快发展，国力日趋增强，中国能源需求保持较快增长趋势，战略储备和生活需要越加明显，大型及特大型化工企业迅速拔地而起。煤化工较普通化工工艺流程长且控制复杂，装置多且装置之间关联性强，一个环节有问题将会联锁多套装置停运甚至发生爆炸。供配电系统作为设备驱动的主要动力源，为设备提供电能，是设备运行的首要条件，供配电系统的可靠运行是工艺稳定生产的关键。

宁煤煤制油项目是典型煤化工的代表，本文以煤制油项目供配电系统为研究对象，通过研究和分析该项目供配电系统的可靠程度，发现系统中影响稳定运行的问题，制定提高系统可靠稳定运行的优化方案。通过对整个系统不同运行方式下短路电流的计算和短路故障对系统影响的研究与分析，发现400V系统是备自投切换，会造成系统短时失电，装置停运，针对此项问题提出了电源快速切换的优化措施；该项目35kV系统中性点经消弧线圈接地，消弧线圈虽能补偿单相接地电容电流，但不能补偿高频电流；化工装置10kV系统中性点不接地，当发生单相接地故障时，没有过电压抑制措施，单相接地会转成相间短路，故障范围扩大，针对35kV和10kV系统两种不同接地方式进行分析，并提出有针对性并符合现场实际的优化措施；该项目低压负荷主要是电动机，控制电动机启停的接触器和变频器都是普通型，不具备抗晃电功能，通过研究晃电对电气设备影响的机理，分析低压设备控制原理，提出不同的优化措施。

基于上述分析和ETAP仿真的基础上，本着改动小、预算少、见效快、收益多的原则，制定了改造优化方案并进行实施。通过改造后的试验和运行情况的跟踪，实现了系统可靠稳定运行的目标，400V系统电源切换由原来的2.5s缩短至现在的100ms左右；当系统发生单相接地故障时，接地电流限制在1A以下，不会产生过电压和电弧，带故障运行2小时不会造成故障范围扩大；低压电动机均增加了抗晃电功能，不会因为晃电而跳闸，导致装置停运，大大提高了化工装置的安全性。

With the steady and rapid development of the national economy and the increasing strength of the nation, China's energy demand keeps a rapid growth trend, and the strategic reserves and living needs become more and more obvious. Coal chemical industry is longer than common chemical process, and its control is complex. There are many devices and they have strong correlation. As the main power source of equipment, power supply and distribution system is the primary condition of equipment operation. The reliable operation of power supply and distribution system is the key to process stability.

The coal-to-oil project in NingXia Coal Industry Co.,Ltd is a representative of typical coal chemical industry，In this paper, the power supply and distribution system of coal-to-oil project as the research object, through the study and analysis of the reliability of the power supply and distribution system of this project, the problems affecting the stable operation of the system are found, make the optimization scheme to improve the reliable and stable operation of the system.Based on the calculation of the short-circuit current and the research and analysis of the influence of the short-circuit fault on the whole system under different operation modes, it is found that the 400V system is the automatic switch of the standby, which will cause the system to lose power and the device to shut down, the neutral point of 35kV system is grounded by arc suppression coil, which can compensate single-phase grounding capacitance current, but can not compensate high frequency current When the neutral point of 10 kv system of chemical plant is not grounded, when the single-phase grounding fault occurs, there is no over-voltage suppression measure, the single-phase grounding will turn into inter-phase short circuit, and the fault range will be expanded, this paper analyzes two different grounding modes of 35kV and 10kV system, and puts forward some optimization measures which are pertinent and accord with the actual situation;The low-voltage load of this project is mainly electric motor, the contactor and frequency converter that control the starting and stopping of electric motor are common type, and do not have anti-sloshing function, the control principle of low-voltage equipment is analyzed, and different optimization measures are put forward.

Based on the above analysis and ETAP simulation, in the light of the principle of small change, less budget, quick effect and more profit, the optimization scheme is made and implemented. Through the test and the tracking of the operation after the transformation, the goal of reliable and stable operation of the system is realized. The power switch of the 400V system is shortened from the original 2.5s to about 100ms now, the grounding current is limited to less than 1A, no overvoltage and arc will occur, and the fault range will not be expanded when the motor is operated with fault for 2 hours, it leads to the shutdown of the plant and greatly improves the safety of the chemical plant.

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