Based on a lot of measurement and analysis,this paper find that the unbalanced nature of 35 kV grids due to unsymmetrical capacitance values gives difficulty in neutral point operation in mountainous area.Improving co...Based on a lot of measurement and analysis,this paper find that the unbalanced nature of 35 kV grids due to unsymmetrical capacitance values gives difficulty in neutral point operation in mountainous area.Improving compensation of Petersen coil can rectify imbalance of voltage but bring up new problem that Petersen coil can not extinguish grounding arc effectively in fault.To put down contradiction mentioned above,this paper proposes a combination operation for neutral point of 35 kV grids as neutral point insulated in routine operation and grounding through Petersen coil in fault,then EMTP simulation is carried out.Simulation indicates that new neutral operation method can improve lightning withstand level and decrease trip-out rate of grids.展开更多
随着分布式电源和电动汽车在配电网的渗透率不断提高,越来越多的电力电子设备接入使得配电系统的谐波治理面临新的挑战。该文从系统耦合特性分析出发,提出一种基于相对增益矩阵(relative gain array,RGA)的多功能并网逆变器(multifuncti...随着分布式电源和电动汽车在配电网的渗透率不断提高,越来越多的电力电子设备接入使得配电系统的谐波治理面临新的挑战。该文从系统耦合特性分析出发,提出一种基于相对增益矩阵(relative gain array,RGA)的多功能并网逆变器(multifunctional grid-tied inverter,MFGTI)协同谐波补偿优化方法。通过引入RGA耦合度分析,构建补偿源与节点电压间的传递特性模型,建立包含耦合度、独立性和综合效能的多维评价指标,实现补偿源的最优配置;提出基于最小二乘法的补偿电流优化算法,在考虑设备容量约束下确定最优补偿策略。结合工程实际,构建综合电气距离和谐波敏感度的评价指标,提出无需量测系统所有节点谐波数据的量测点筛选方法。算例对比分析和仿真验证结果表明,所提方法能够协调多台MFGTI对配电系统的谐波进行综合补偿,有效降低系统谐波污染水平。展开更多
讨论非结构网格上温度扩散方程的能流计算方法.应用有限点方法(Finite Point Method,简称FPM)导出基于有限点两点公式和三点公式的能流计算公式,该公式适用于任意多边形及非匹配网格等非结构网格;给出网格角点温度新的计算公式.数值试...讨论非结构网格上温度扩散方程的能流计算方法.应用有限点方法(Finite Point Method,简称FPM)导出基于有限点两点公式和三点公式的能流计算公式,该公式适用于任意多边形及非匹配网格等非结构网格;给出网格角点温度新的计算公式.数值试验表明:基于两点公式的离散解和基于三点公式的离散解均具有平方阶的收敛速度;基于三点公式的离散解的精度总优于基于两点公式的离散解.展开更多
基金Project Supported by Natural Science Foundation of CQ CSTC （ 2005BA6021 ）.
文摘Based on a lot of measurement and analysis,this paper find that the unbalanced nature of 35 kV grids due to unsymmetrical capacitance values gives difficulty in neutral point operation in mountainous area.Improving compensation of Petersen coil can rectify imbalance of voltage but bring up new problem that Petersen coil can not extinguish grounding arc effectively in fault.To put down contradiction mentioned above,this paper proposes a combination operation for neutral point of 35 kV grids as neutral point insulated in routine operation and grounding through Petersen coil in fault,then EMTP simulation is carried out.Simulation indicates that new neutral operation method can improve lightning withstand level and decrease trip-out rate of grids.
文摘随着分布式电源和电动汽车在配电网的渗透率不断提高,越来越多的电力电子设备接入使得配电系统的谐波治理面临新的挑战。该文从系统耦合特性分析出发,提出一种基于相对增益矩阵(relative gain array,RGA)的多功能并网逆变器(multifunctional grid-tied inverter,MFGTI)协同谐波补偿优化方法。通过引入RGA耦合度分析,构建补偿源与节点电压间的传递特性模型,建立包含耦合度、独立性和综合效能的多维评价指标,实现补偿源的最优配置;提出基于最小二乘法的补偿电流优化算法,在考虑设备容量约束下确定最优补偿策略。结合工程实际,构建综合电气距离和谐波敏感度的评价指标,提出无需量测系统所有节点谐波数据的量测点筛选方法。算例对比分析和仿真验证结果表明,所提方法能够协调多台MFGTI对配电系统的谐波进行综合补偿,有效降低系统谐波污染水平。
文摘讨论非结构网格上温度扩散方程的能流计算方法.应用有限点方法(Finite Point Method,简称FPM)导出基于有限点两点公式和三点公式的能流计算公式,该公式适用于任意多边形及非匹配网格等非结构网格;给出网格角点温度新的计算公式.数值试验表明:基于两点公式的离散解和基于三点公式的离散解均具有平方阶的收敛速度;基于三点公式的离散解的精度总优于基于两点公式的离散解.
