A control system for providing commands to a multi-level converter for balancing a neutral point voltage of the multi-level converter, the control system comprising: a fundamental control unit for generating fundamental commands to implement fundamental power conversion operation for the multi-level converter; characterized by: a first compensation control unit for generating a first compensation signal for injection into the fundamental command to balance the neutral point voltage when the multi-level converter is in operation in a first state corresponding to a normal operation state of a power conversion system working in a state when the active power is not equal to zero; a second compensation control unit for generating a second compensation signal for injection into the fundamental command to balance the neutral point voltage when the multi-level converter is in operation in a second state, wherein the first state is different from the second state corresponding to the power conversion system working in a state when the active power is equal to zero; a switch control unit for detecting the state of the multi-level converter and providing a first switch signal and a second switch signal respectively corresponding to the first state and the second state; and a switch implementation unit for switching the fundamental control unit to communicate with the first compensation control unit according to the first switch signal and for switching the fundamental control unit to communicate with the second compensation control unit according to the second switch signal. a fundamental control unit for generating fundamental commands to implement fundamental power conversion operation for the multi-level converter; characterized by: a first compensation control unit for generating a first compensation signal for injection into the fundamental command to balance the neutral point voltage when the multi-level converter is in operation in a first state corresponding to a normal operation state of a power conversion system working in a state when the active power is not equal to zero; a second compensation control unit for generating a second compensation signal for injection into the fundamental command to balance the neutral point voltage when the multi-level converter is in operation in a second state, wherein the first state is different from the second state corresponding to the power conversion system working in a state when the active power is equal to zero; a switch control unit for detecting the state of the multi-level converter and providing a first switch signal and a second switch signal respectively corresponding to the first state and the second state; and a switch implementation unit for switching the fundamental control unit to communicate with the first compensation control unit according to the first switch signal and for switching the fundamental control unit to communicate with the second compensation control unit according to the second switch signal. a first compensation control unit for generating a first compensation signal for injection into the fundamental command to balance the neutral point voltage when the multi-level converter is in operation in a first state corresponding to a normal operation state of a power conversion system working in a state when the active power is not equal to zero; a second compensation control unit for generating a second compensation signal for injection into the fundamental command to balance the neutral point voltage when the multi-level converter is in operation in a second state, wherein the first state is different from the second state corresponding to the power conversion system working in a state when the active power is equal to zero; a switch control unit for detecting the state of the multi-level converter and providing a first switch signal and a second switch signal respectively corresponding to the first state and the second state; and a switch implementation unit for switching the fundamental control unit to communicate with the first compensation control unit according to the first switch signal and for switching the fundamental control unit to communicate with the second compensation control unit according to the second switch signal.