【摘要】 光伏发电系统大规模接入电网挤占了具有转动惯性和一次调频特性的同步发电机组空间,增大了电网运行时的频率波动,这就迫切需求光伏主动参与系统的频率调节.文中提出了一种无任何外部存储元件,仅利用自身输出的两级式光伏发电系统的频率控制方案.当检测到频率变化时,利用逆变器直流环节电容中存储的能量来实现同步发电机的虚拟惯性特性.同时,通过减少光伏阵列的实际工作电压,保留一定的功率余量,为光伏发电系统提供了参与一次频率控制的能力.在DIgSILENT/PowerFactory中进行了仿真,结果表明:光伏发电系统在设定的控制模式下能够增发或减少储备的有功功率,抑制频率的升高或跌落,而无任何的附加储能,这与大多数需要利用蓄电池等元件进行调控的系统相比,大幅度节省了投资的成本.在扰动状态下,直流电容确保了不变的功率输出和吸纳,相比单一减载下的光伏发电系统,可以稳定有效调节频率的波动.更多还原

【Abstract】 The large-scale connection of photovoltaic system into power grid occupies the space of synchronous generator units with rotational inertia and primary frequency regulation characteristics,which increases the frequency fluctuation of power grid operation.Therefore,it is urgent to actively participate in the frequency regulation of photovoltaic system.In this paper,a frequency control scheme of two-stage photovoltaic system without any external storage elements and only using its own output is proposed.When the frequency change is detected,the energy stored in the DC link capacitor of the inverter is used to realize the virtual inertia characteristics of the synchronous generator.At the same time,by reducing the actual working voltage of PV array and reserving certain power margin,it provides the ability of participating in primary frequency control for photovoltaic system.The simulation results in DIgSILENT/PowerFactory show that the photovoltaic system can generate or reduce the reserve active power,suppress the rise or fall of frequency without any additional energy storage under the set control mode,which greatly saves the cost of investment compared with most systems that need to use battery and other components for regulation.In the disturbance state,the DC capacitor ensures the constant power output and absorption,which can effectively adjust the frequency fluctuation compared with the photovoltaic system under single load shedding.更多还原