基于风险策略的配电网铁磁谐振故障分析与抑制措施研究

Ferromagnetic Resonance Fault Analysis and Suppression Measures of Distribution Network Based on Risk Strategy

一般认为母线容性电流在0 A~20 A范围内都有铁磁谐振风险,应采取预防措施,但是当处于临界区域时,往往难于“抉择”。为规避谐振危害,合理科学地选择治理措施,本研究讨论了铁磁谐振受电压互感器伏安特征影响的规律,并提出了消谐措施的应用方法。首先,根据谐振机理与不同类型配电网谐振特点对铁磁谐振的风险因素进行总结归纳;然后,使用PSCAD搭建仿真模型,对某型号为JDZJ的电压互感器进行伏安特性实测,拟合了电压互感器伏安特性曲线,精准建模;接着,通过概率手段研究了电压互感器伏安特性改善、电容值变化对铁磁谐振风险概率的影响,得到伏安特性饱和拐点提高到一定水平后谐振风险降低,电容值在电压互感器伏安特性提高后对谐振风险影响变小的结论,验证了《国家电网公司十八项电网重大反事故措施》中电压互感器伏安特性饱和点应大于1.9U_(m)/√3的合理性;最后仿真研究了采用一二次消谐措施后的消谐效果及系统谐振风险变化情况,从概率角度验证了消谐措施的有效性,为配电网的规划、电压互感器伏安特性选取和消谐措施选择提供了参考。

It is generally believed that there is a risk of ferromagnetic resonance when the capacitive current of the bus is in the range of 0 A~20 A,and preventive measures should be taken at this time.However,when it is in the critical area,it is often difficult to "choose".In order to avoid the harm of resonance and select treatment measures reasonably and scientifically,the author discusses the law of ferromagnetic resonance affected by the volt-ampere characteristics of voltage transformer,and puts forward the application method of harmonic elimination measures.Firstly,the risk factors of ferromagnetic resonance are summarized according to the resonance mechanism and the resonance characteristics of different types of distribution networks;Secondly,PSCAD is used to build the simulation model.The volt-ampere characteristics of a certain type of voltage transformer JDZJ are measured,and the volt-ampere characteristic curve of the voltage transformer is fitted to accurately model it.Thirdly,the influence of the improvement of volt-ampere characteristics of voltage transformer and the change of capacitance on the risk of ferromagnetic resonance are studied by means of probability.It is concluded that the resonance risk is reduced when the saturation inflection point of volt-ampere characteristics is increased to a certain level,and the influence of capacitance on the resonance risk is reduced when the volt-ampere characteristics of voltage transformer are improved.The rationality that the volt ampere characteristic saturation point of voltage transformer should be greater than 1.9U_(m)/√3 in “Eighteen Major Anti Accident Measures of State Grid Corporation of China”is verified;Finally,the harmonic elimination effect and the change of system resonance risk after using the primary and secondary harmonic elimination measures are simulated and studied.The effectiveness of the harmonic elimination measures is verified from the perspective of probability,which provides a reference for the planning of distribution network,the selection of volt ampere characteristics of voltage transformer and the selection of harmonic elimination measures.