Abstract: A large-scale photovoltaic direct current (DC) series boost grid-connected system with a power balancer, including N photovoltaic DC converters and N?1 power balancers, wherein N?2. The output ends of the photovoltaic DC converters are connected successively in series and then connected to the DC grid, and the input ends of the photovoltaic DC converters are respectively connected to the output ends of the photovoltaic power generation unit. Among the photovoltaic DC converters, which are arranged successively in series, a power balancer is disposed between the input ends of two photovoltaic DC converters adjacent to each other. The N?1 power balancers are arranged corresponding to the set N?1 photovoltaic DC converters respectively to balance the input power of the corresponding photovoltaic DC converter, thereby eliminating a difference between the output voltages of the photovoltaic DC converters.

Abstract: A large-scale photovoltaic direct current (DC) series boost grid-connected system with a power balancer, including N photovoltaic DC converters and N?1 power balancers, wherein N?2. The output ends of the photovoltaic DC converters are connected successively in series and then connected to the DC grid, and the input ends of the photovoltaic DC converters are respectively connected to the output ends of the photovoltaic power generation unit. Among the photovoltaic DC converters, which are arranged successively in series, a power balancer is disposed between the input ends of two photovoltaic DC converters adjacent to each other. The N?1 power balancers are arranged corresponding to the set N?1 photovoltaic DC converters respectively to balance the input power of the corresponding photovoltaic DC converter, thereby eliminating a difference between the output voltages of the photovoltaic DC converters.

Abstract: A series-type photovoltaic high-voltage direct current (DC) grid-connected converter topological circuit and a modulation method thereof, wherein the topological circuit includes a high-frequency transformer configured to isolate a primary side circuit from a secondary side circuit. The primary side circuit includes a high-frequency full-bridge inverter circuit, an active-clamping circuit, an input capacitor C1, an input diode D0, and a boost inductor L1 and adjusts the boost mode and buck mode of the topological circuit. The secondary side circuit includes a high-frequency rectifying circuit, a filter capacitor C3 and a filter capacitor C4, and rectifies and filters an output voltage of the high-frequency transformer. The secondary side circuit further includes a switch tube Q5, and the switch tube Q5 adjusts the secondary side circuit into a voltage multiplication circuit to double the output voltage of the high-frequency transformer.