基于串联制动电阻的生物质能同步发电机组低电压穿越研究

SBR-based LVRT of synchronous generators in biomass power plants

对用于生物质能发电(BPP)的并网同步机组(SG),其低电压穿越(LVRT)不便沿用大型SG紧急控制措施。采用串联制动电阻(SBR)实现BPP中SG的LVRT,采用计及励磁系统动态控制的等面积定则,提出了SBR阻值解析算法。基于SG及励磁系统,量化SBR功率,将其引入SG加速面积中,建立了SG加速和减速面积表达式。结合机械功率和切入功角,利用等面积定则,推导出满足LVRT准则SBR最小阻值的解析算法。改变系统参数,分析其对SBR最小阻值的影响,以选择新安装BPP电厂参数。动态仿真结果验证了基于解析算法选取SBR阻值的正确性。可以发现SG惯性或励磁电压上限越大,q轴同步电抗、d轴暂态电抗或变压器电抗越小,机械功率或切入功角越小,所需的SBR阻值越小。对SBR阻值影响从大到小依次排序为d轴暂态电抗、惯性时间常数、q轴同步电抗、变压器电抗、励磁电压上限值。

As the LVRT（Low-Voltage Ride-Through） method for large-scale SG（Synchronous Generator） is not suit for the SG in BPP（Biomass Power Plant）,SBR（Series Braking Resistor） is applied to achieve the LVRT of SG in BPP. An analytical method based on the equal area criterion considering the dynamic control of excitation system is proposed to calculate the resistance of SBR. Based on the excitation control system and SG model,the active power of SBR is quantified and introduced to the accelerating area for building the expressions of accelerating area and decelerating area. Combined with the mechanical power and switch-in rotor angle,the equal area criterion is applied to deduce the analytical method for calculating the minimum SBR to meet the requirements of LVRT. The influences of different system parameters on SBR are analyzed for determining the parameters of new BPP. The results of dynamic simulation verify the correctness of the introduced analytical method. It is found that,larger inertia of SG or upper limit of field voltage,smaller qaxis synchronous reactance or d-axis transient reactance or transformer reactance and smaller mechanical power or switch-in rotor angle will require smaller resistance of SBR. Arranged from bigger to smaller according to their impacts on SBR,the influencing system parameters are d-axis transient reactance,SG inertia time constant,q-axis synchronous reactance,transformer reactance and upper field voltage limit.