大型办公楼配电系统的谐波评估与抑制

为评估大型办公楼配电系统的谐波水平，寻求抑制谐波的方法，对该系统的特点进行了分析．应用公用电网谐波国家标准，确定了两层公共连接点（ＰＣＣ）上的谐波限值．在香港的１４ 座办公楼中对各ＰＣＣ的谐波水平进行了评估．发现有些情况下电压和电流的谐波畸变水平都超出了限定值，租户供电电路的谐波畸变尤其严重，有些直立干线上的电压总谐波畸变率甚至超过１５％ ．对照明、小功率用电和空调电路等分支电路中的谐波情况也进行了调查，总结了其谐波特点．基于对谐波评估结果的分析，提出了控制谐波源，减小直立干线阻抗，均衡布置非线性负荷，利用谐波的集合效应等谐波抑制措施．

Harmonic Evaluation and Mitigation in Distribution Systems for Large Office Buildings

Harmonic limits in public supply networks were provided in the China National Standard GB/T14549 93. The characteristics of the office building distribution systems were analyzed for harmonic evaluation and mitigation in such systems. Applying GB/T14549 93 in particular distribution systems, two layers of points of common coupling (PCCs) were introduced. The harmonic limits on PCCs were clarified. Harmonic survies were carried out in 14 office buildings in Hong Kong. The harmonic levels on PCCs were evaluated. It was found that harmonic distortion levels at the PCCs exceed the limits in some cases. Harmonic distortions in tenant supply circuits are especially serious. The voltage total harmonic distortions on some risers even exceed 15%. Harmonic distortion levels in some branch circuits, such as lighting, small power and air conditioning circuits were also investigated. Based on the analysis of the evaluation results, some technical measures for mitigation of harmonics were provided, such as restricting harmonic sources, reducing the riser impedances and using the harmonic grouping effects, etc.