This article examines and studies a coal-chemical plant through a dynamic computer model as well as designs an automatic load-shedding protection. The plant has on-site generation to support partial plant loads. In the past, disconnecting from the utility grid had caused frequency and voltage decays in the plant electrical system to dropout critical loads. A complete system computer model is constructed, including generator dynamics, excitation/automatic voltage regulators (AVRs), and prime mover/governor control characteristics. Transient stability simulations of various loading and generation conditions were carried out to understand and study system frequency and voltage behaviors and patterns of change under a sudden islanding case. This was accomplished by analyzing frequency versus time and rate of change of frequency versus time curves. Further, through carefully evaluating plant load priorities as well as load dependencies, a feasible load-shedding control scheme with backup strategies was configured and simulated by computer modeling and study. Simulation results verified that the proposed loadshedding scheme can correctly respond to frequency drop and automatically initiate the shedding of noncritical and independent loads to prevent further system frequency drop, thereby exceeding the allowable deviation. The suggested solution is automatic and feasible and has been successfully implemented at the plant.

中文翻译：

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某煤化厂自动减载保护

本文通过动态计算机模型对煤化工厂进行了研究和研究，并设计了自动减载保护。该工厂具有现场发电以支持部分工厂负载。过去，与公用电网断开连接会导致工厂电气系统中的频率和电压衰减，从而导致关键负载丢失。构建了完整的系统计算机模型，包括发电机动力学、励磁/自动电压调节器 (AVR) 和原动机/调速器控制特性。进行了各种负载和发电条件的瞬态稳定性模拟，以了解和研究突然孤岛情况下的系统频率和电压行为以及变化模式。这是通过分析频率对时间和频率对时间曲线的变化率来实现的。此外，通过仔细评估电厂负荷优先级以及负荷依赖性，通过计算机建模和研究，配置和模拟了具有备份策略的可行减载控制方案。仿真结果验证了所提出的减载方案能够正确响应频率下降并自动启动非关键和独立负载的减载，以防止系统频率进一步下降，从而超过允许偏差。建议的解决方案是自动且可行的，并已在工厂成功实施。仿真结果验证了所提出的减载方案能够正确响应频率下降并自动启动非关键和独立负载的减载，以防止系统频率进一步下降，从而超过允许偏差。建议的解决方案是自动且可行的，并已在工厂成功实施。仿真结果验证了所提出的减载方案能够正确响应频率下降并自动启动非关键和独立负载的减载，以防止系统频率进一步下降，从而超过允许偏差。建议的解决方案是自动且可行的，并已在工厂成功实施。