Background harmonic voltage test and evaluation

In the harmonics filed research, background harmonic voltage is always important. It is very crucial to the objectivity and rationality of the results. For example, when electric power companies distribute the harmonic voltages (currents) limit to customers, the background harmonic level of the POE should be taken into account. In the design of passive power filters, the background harmonic level of the POC should also be considered to get rational filter capacities. For the operating power grids, background harmonics can be obtained by field tests. However, due to the randomness of harmonics, it is related to the power grid structures, operating modes, load distributions etc. As a result, it is also needed to make a feasible test plan and method to get true and representative test results. For planning grids of the level year, background harmonics should be calculated and evaluated according to the existing grids. According to related national standards and referring to related IEC latest standards, this paper introduce test plans, selection criteria of test equipments, arrangement of the test time and data treatment methods etc. For the background harmonic prediction and evaluation of the level year, this paper introduces planning grids´ construction, equivalent points´ setting, calculation programs´ selection, harmonic current sources´ model and arrangement, background harmonic voltage calculation methods of the level year. This paper´s research has been successfully employed in the Xiangjiaba-Shanghai Ultra-HVDC Engineering.