水电机组一次调频理论积分电量计算方法

Calculation Method of Theoretical Integral Electric Quantity for Primary Frequency Regulation of Hydropower Units

2019年西南地区异步联网后,水电机组一次调频能力受到巨大考验,电网频率波动明显增大,电站一次调频动作次数呈10倍增加,导致一次调频考核合格率大幅降低。研究发现当前电网考核机组一次调频理论积分电量计算方式存在一定不足,即一次调频理论电量与电网频率呈正比关系,但实际水轮发电机组一次调频调节速率受PID参数、控制系统机械调节速率及水轮机水流惯性时间常数的影响,功率变化速率较慢,一次调频理论积分电路与实际功率变化偏差较大,导致水电机组一次调频考核不合格率大幅增加;对水轮发电机组调节系统整体建模,并根据实际情况合理简化得到简单准确的一阶模型,通过对简化模型的传递函数拉氏反变换得到指数函数,由此计算水电机组一次调频理论积分电量,实测对比证明采用指数函数计算一次调频理论积分电量准确度高,符合水电机组一次调频调节规律。

After the asynchronous interconnection in Southwest China in 2019,the primary frequency regulation capacity of hydropower units will be greatly tested,the frequency fluctuation of power grid will increase significantly,the number of primary frequency regulation actions of power stations will increase 10 times.and the qualification rate of primary frequency regulation assessment will decrease significantly.Through research,it is found that the calculation method of theoretical integral power of primary frequency regulation of current power grid assessment units has someshortcomings.The theoretical power of primary frequency regulation has a positive proportional relationship with power grid frequency.However,the actual primary frequency regulation rate of hydro generator units is affected by PID parameters.mechanical regulation rate of control system and hydraulic turbine flow inertia time constant.The power change rate is slow.The deviation between the theoretical integral circuit and the actual power is large,which leads to a substantial increase in the unqualified rate of the primary frequency regulation assessment of hydropower units.Through the analysis of the overall modeling of the regulating system of hydro generator units,and according to the actual situation,a simple and accurate first-order model is obtained after reasonable simplification.The exponential function is obtained through the inverse Laplace transform of the transfer function of the simplified model.The calculation of the theoretical integral power of primary frequency regulation of hydropower units shows that the exponential function has high accuracy in calculating the theoretical integral power of primary frequency regulation,which is in line with the regulation law of primary frequency regulation of hydropower units.