MIXED INITIATIVE AND ANTI-ISLANDING DETECTION METHOD AND SYSTEM

摘要

A mixed initiative and anti-islanding detection method and system. The method comprises the following steps: acquiring the change value ∆ωof the grid frequency in each control period, and acquiring the effect of the change value ∆ωof the grid frequency on the reactive power reference value Q ref by using a positive feedback frequency shift method and through gain processing, the correspondence between the change value ∆Q GCC of the reactive power reference value Q ref in each control period and ∆ωbeing as follows: ∆Q GCC =Κpf ∆ω, wherein K pf is the gain in the islanding effect pre-detection; when frequency shift occurs in the change value ∆ωof the grid frequency at 0.1Hz, determining that the islanding phenomenon probably occurs in an inverter, and triggering an initiative islanding detection method to perform further islanding detection; and otherwise, re-acquiring the change value ∆ωof the grid frequency, and performing gain processing on the ∆ω. In this method, only when the islanding effect is found through detection, an interference signal can be input to the power grid, and an RS flip-flop is used to trigger the initiative islanding detection method at the same time in all inverters, thereby ensuring the synchronization between all inverters, eliminating the dilutive effect in a distributed power generation system, and finally ensuring the effectiveness of the islanding effect detection.