A Control Strategy for Smoothing Active Power Fluctuation of Wind Farm with Flywheel Energy Storage System Based on Improved Wind Power Prediction Algorithm

The fluctuation of active power output of wind farm has many negative impacts on large-scale wind power integration into power grid. In this paper, flywheel energy storage system (FESS) was connected to AC side of the doubly-fed induction generator (DFIG) wind farm to realize smooth control of wind power output. Based on improved wind power prediction algorithm and wind speed-power curve modeling, a new smooth control strategy with the FESS was proposed. The requirement of power system dispatch for wind power prediction and flywheel rotor speed limit were taken into consideration during the process. While smoothing the wind power fluctuation, FESS can track short-term planned output of wind farm. It was demonstrated by quantitative analysis of simulation results that the proposed control strategy can smooth the active power fluctuation of wind farm effectively and thereby improve power quality of the power grid.

永磁直驱风电低电压穿越与功率平抑策略研究

针对永磁直驱风电机组低电压穿越和功率平抑两种问题,提出采用改进超级电容储能系统(ISCESS)和串联制动电阻(SDBR)的联合控制策略。将ISCESS并联在机组的直流链上,SDBR则串联在电网与并网点之间。当风电并网系统正常运行时,ISCESS凭借快速充放电能力平抑机组的并网功率。当电网故障电压骤降时,SDBR抬升并网点的电压并耗散不平衡能量,另一部分不平衡能量则由ISCESS吸收。研究结果表明,所提策略在正常运行时能有效对永磁直驱风电机组的并网功率进行平抑,在电网故障时能有效提升机组的低电压穿越能力。

动态三次指数平滑法的火电厂发电量预测研究

研究具有动态平滑系数和参数的动态三次指数平滑法在火电厂发电量预测的适用性,并且与传统的时间序列预测模型加权移动平均法进行比较。以部分河北省邯郸市的火电厂发电量为研究对象,对月发电量进行预测。通过采集到的发电量数据对两种预测模型进行编译和实现,并嵌入预测干预法,通过相对误差和方差的比较,证明基于动态三次指数平滑的时间序列预测模型具有良好的预测精度和预测数据拐点的能力,在火电厂发电量的预测中有较高的实用性。

有源滤波器在大功率工程中的应用

对于大功率非线性负载,有源电力滤波器受到变流器晶体管功率和开关频率的限制,不能有效地抑制负载谐波电流.为此,提出了一种由并联有源滤波器和串联平波电抗器组成的混合有源滤波系统.实验结果表明,这种滤波系统在不加大有源滤波器带宽的条件下不仅滤波效果明显,而且容量要求小,仅为负载平均功率的2%或更低.

隐式曲面的一种光滑拼接定义

利用函数的幂级数给出了隐式曲面的一种光滑拼接定义 ,证明了在此定义下的k阶光滑拼接即为k阶变尺度连续 。