含矿热炉负载的孤网运行稳定性与综合补偿研究

发布时间：2018-05-09 13:09

本文选题：孤网 + 矿热炉　；参考：《华北电力大学(北京)》2016年硕士论文

【摘要】：矿热炉是冶金工业中一种重要的负荷。由于其冶炼过程中存在功率的经常性波动,一般要求接入大电网运行。然而,在一些电网建设落后,但矿产资源十分丰富的地区,若要发展铁合金冶炼项目,只能考虑自备电厂孤网运行方案。孤网系统频率易受负荷扰动影响,而矿热炉冶炼过程中存在功率随机波动,极端工况下会瞬时失去大量负荷,可能使系统频率、电压超出允许范围,甚至引起发电机保护动作导致系统失稳。本文首先建立了孤网系统数学模型,分析了SPLC调节负荷功率的原理和控制策略,指出了恒功率控制可实现的临界工况。在此基础上,提出了SPLC和制动电阻协调控制的矿热炉孤网运行功率稳控策略。针对矿热炉短路工况下系统母线电压跌落的问题,提出了增大SPLC阻抗以支撑母线电压的控制方案。仿真结果表明,采用所提方案能实现各种工况下发电机输出功率的稳定和短路工况下母线电压的稳定,为矿热炉长期孤网稳定运行提供了可靠保障。由于矿热炉是非线性、时变负载,给系统带来了谐波和三相不平衡问题,而SPLC和制动电阻也会产生谐波电流,为此,本文研究了基于角型链式STATCOM的矿热炉供电系统综合补偿方案。仿真结果表明,采用所述方案,大大减小了孤网供电系统网侧的谐波、无功和负序电流,不仅有利于保护发电机本体,且提高了供电质量。
[Abstract]:Ore-heating furnace is an important load in metallurgical industry. Due to the frequent fluctuation of power in the smelting process, it is generally required to connect to the large power grid. However, in some areas where the construction of power grid is backward but the mineral resources are very rich, if we want to develop the ferroalloy smelting project, we can only consider the operation scheme of the isolated network of our own power plant. The frequency of the isolated grid system is easily affected by the load disturbance, but there is a random fluctuation of power in the smelting process of the furnace, which may cause the frequency and voltage of the system to exceed the allowable range because of the instantaneous loss of a large amount of load under extreme working conditions. Even causes the generator protection action to cause the system to lose the stability. In this paper, the mathematical model of isolated network system is established, the principle and control strategy of load power regulation by SPLC are analyzed, and the critical condition of constant power control is pointed out. On this basis, the power stability control strategy of SPLC and brake resistance coordinated control is put forward. In order to solve the problem of bus voltage drop under short-circuit condition of mine furnace, the control scheme of increasing SPLC impedance to support bus voltage is put forward. The simulation results show that the proposed scheme can achieve the stability of generator output power under various operating conditions and the stability of bus voltage under short-circuit conditions, which provides a reliable guarantee for the long term isolated network operation of the furnace. Because the thermal furnace is nonlinear and time-varying load, it brings harmonic and three-phase imbalance problem to the system, and SPLC and brake resistance also produce harmonic current. In this paper, a comprehensive compensation scheme for power supply system of thermal furnace based on angle chain STATCOM is studied. The simulation results show that the proposed scheme can greatly reduce the harmonic, reactive and negative sequence currents of the grid side of the isolated power supply system, which is not only conducive to the protection of the generator body, but also improves the power supply quality.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM712

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