Full-band Integrated Power/data Coordinated Control Methods In DC Microgrids

As an essential part of the future intelligent power distribution system,DC microgrid plays an important role to the ’’emission peak and carbon neutrality goals’ ’.The integrated power/data coordinated control(IPDCC)target caters to the integration,intelligence,and security demands of DC microgrids,thus it has broad research prospects.In this paper,according to the basic characteristics of power electronics converters in different frequency bands,the basic theory of IPDCC is proposed.Furthermore,the specific solutions to the key IPDCC problems in lowfrequency,middle-frequency,and high-frequency bands are proposed and introduced in detail.First,the basic theory of full-band IPDCC method is proposed.Based on the deconstruction results of power electronics converters,the whole frequency band is divided into three parts: lowfrequency band,middle-frequency band,and high-frequency band.The converter’s basic characteristics in each band are clarified,based on which the unified design approaches of the IPDCC method are put forward.According to the band division results,the noises in IPDCC system are classified,and a generalized method of the signal-to-noise ratio(SNR)analysis is proposed,which provides theoretical guidance for future studies.Second,an IPDCC method in low-frequency band is proposed.The method realizes peerto-peer(P2P)power flow tracing based on bus-port impedances of converters,which ensures the accuracy and fairness of P2 P electricity trading.In this method,the bus-port impedance characteristics of source and load converters should be precisely controlled.A low-frequency AC carrier with controllable active power is sent by a source converter to carry the DC power flow information.The method includes source-to-load P2 P power signaling and source-to-source P2 P power verification technique.In the source-to-load P2 P power signaling technique,the load converter calculates the P2 P DC transferred power from a specific source by measuring the AC carrier’s active power at the bus port of the load.The source-to-source P2 P power verification technique checks the actual DC output power of each source by using the droop characteristics and the amplitudes of the AC carrier.The effectiveness and feasibility of the proposed method are verified on a 3k W DC microgrid experimental platform.Third,the IPDCC method in middle-frequency band is demonstrated and developed.The method embeds carrier communication into power control loop,providing a more economical and reliable solution for the efficient autonomy of DC microgrids.Aiming at the real-time,high-speed,and long-distance requirements in the voltage coordination layer communication of DC microgrids,the Orthogonal Frequency Division Multiplexing(OFDM)technology is introduced into the traditional method to maximize the utilization of the bandwidth.The DC microgrid in the middle-frequency is modelled,and the channel characteristics are explored,based on which the corresponding design rules of the system parameters are proposed.Besides,the inter-symbol interference(ISI)and peak-to-average ratio(PAPR)problems are analyzed and the corresponding solutions are provided.The effectiveness and feasibility of the proposed method are verified on a3 k W DC microgrid experimental platform.Fourth,the IPDCC methods in high-frequency band are demonstrated and developed.The methods embed data communication into the switching modulation process in the power converters,which provides a safe and reliable approach for energy stamping in DC microgrids.An isolated power/data time-division multiplexing transmission method is proposed for the battery management system(BMS)in DC microgrids,and the basic principles and system design criteria are described in detail.The boundary conditions for the maximum number of nodes are derived.In order to enhance the anti-interference and reliability performance,the power/data frequency-division multiplexing transmission methods based on Chirp spread spectrum and symmetrical binary frequency hopping-direct sequence spread spectrum(SBFH-DSSS)are respectively proposed,and multi-agent communication protocols are designed for the two methods.The feasibility and effectiveness of the above methods are verified on a 3k W DC microgrid experimental platform.