This paper explores the application of symmetric monopolar topology in embedded HVDC systems and analyzes the adaptability issues faced when using symmetric bipolar topology control and protection strategies. First

based on the control strategy of the symmetric monopolar topology HVDC system

the paper analyzes the steady-state characteristics of the system when a ground fault occurs on the positive or negative pole DC line. On this basis

combined with the low voltage protection criteria for DC lines

it was found that if a symmetric monopolar system uses the DC line current of the negative pole as the controller input

the low voltage protection will fail to operate when a high-resistance transition fault occurs on the positive pole line. To ensure reliable operation of low voltage protection in both positive and negative pole line faults

this paper innovatively proposes two coordinated control and protection optimization strategies: DC adaptive switching control and independent control. After adopting these two coordinated control strategies

the performance of the low voltage protection was verified using a semi-physical digital simulation platform for embedded DC engineering. Theoretical analysis and experimental results show that compared to the independent control strategy

the adaptive switching control strategy can avoid injecting harmonics into the grid and reduce the requirements for the neutral point's voltage withstand capability

thus recommending adopting this strategy in practical engineering applications.