计及锅炉动态的直流受端系统中长期频率响应计算方法

Mid-term and long-term frequency calculation method for the HVDC receiving-end system considering the boiler dynamics

直流故障后系统动态过程持续时间较长,计算中长期频率响应需要计及锅炉的动态。首先推导了直流受端系统的低阶频率响应模型,简要介绍了火力发电厂锅炉及机炉协调控制系统的工作原理。其次,提出采用非机理建模方法建立描述发电机机械功率-频率特性的传递函数模型。进行负荷扰动试验,量测并记录系统频率及发电机机械功率偏差量。在此基础上,应用功率谱及最小二乘法辨识模型参数,对负荷扰动试验时的扰动信号、样本选取等进行了讨论。最后,将该方法应用于含直流落点的IEEE3机9节点系统,计算了直流闭锁后受端系统的中长期频率响应,验证了基于辨识模型计算方法的有效性。

The dynamic process of power system after DC blocking will last for a long time.The boiler dynamics should be taken into consideration when calculating the system frequency response.Firstly,the low order frequency response model of the DC receiving-end system is derived.The boiler and the coordinated control system of the thermal power plant are introduced briefly.Then,the non-mechanism modeling method is adopted to establish the transfer function model which describes the mechanical power-frequency characteristics of the generator.The load disturbance test is carried out and the frequency and mechanical power deviations of the generator are measured.The power spectrum and the least square methods are applied to identify parameters of the transfer function model.The selection of load disturbance signal and samples is discussed.Finally,the proposed method is applied in the IEEE 3-generator 9-bus system with a DC feed line.The long-term frequency response of the receiving-end system after DC blocking is calculated.The results validate the effectiveness of the identified model considering boiler dynamics.