Study On The Adaptive Power Controller In Medium-low Voltage Distribution Network

Adaptive power controller, as a new type of flexible distributiondevices, can meet the comprehensive requirements of smart distribution grid,resolve most of problems in medium-low voltage distribution network,supply special power services for users, and achieve the bumpless access ofdistributed generation, thereby which will enhance the stability, reliabilityand economy of power supplying system. In the domestic adaptive powercontroller is still in the stage of basic theory. This dissertation has focusedon the mathematical modeling and control strategy of the adaptive powercontroller, and the works and innovative achievements are as follows.1. The continuous average mathematical model of adaptive powercontroller in the frequency domain is built up, and the impact of equipmentsand control parameters on the device overall performance are analyzed. Thedesign methods and principles of hardware parameters in adaptive powercontroller are suggested, under the affect of the optimization of controlobjectives, power constraints and nonlinear factor.2. Integrated synchronous control strategy based on the positive andnegative sequence separation decoupling is established. The active powerand reactive power expression based on the average power definition arederived in detail for the DC bus voltage imbalance problem of cascadedconverter. A single phase DC bus voltage balance control strategy based onnegative sequence current is given, and a hierarchical distributed DC busvoltage balance control strategy to achieve the adaptive balance of DC busvoltage in input stage is designed in this paper. In order to satisfy thefunctional requirements of input stage in adaptive power controller, the adaptive reactive power and harmonic compensation strategies are built up,which can meet the requirements of power system.3. The high performance software phase locked loop and overcurrentprotection strategy are studied. Owing to the difficult problem of accuratephase lock in fault conditions of power system, the enhanced phase lockedloops based on the lead-correction function and the repetitive controltechnique are developed, which improve the dynamic performance andsteady state characteristics of device under fault conditions. For theovercurrent problem in failure conditions, a steady overcurrent auxiliarycontroller and transient overcurrent suppression method are discussed,which improve the fault viability of adaptive power controller.4. Multi-terminal DC bus voltage control strategy of adaptive powercontroller is built up. The fast balance algorithm including DC voltage outerloop and the current root mean square value (RMS) inner loop is proposedfor the problem of DC bus voltage fluctuation in DC/DC converter paralleloperation,. Due to the equalization power issue of parallel power module,the average power algorithm based on the current RMS is designed. Thelayered composite magnetic bias suppression strategy is raised for themagnetic bias of the medium/high frequency transformer, which improvethe operational reliability of adaptive power controller.5. The cascaded power supplying scheme of Premium Power Park isproposed. Owing to the quality requirements for the power supplying ofPremium Power Park, the comprehensive solutions integrated adaptivepower controller is established, and the functional requirements of adaptivepower controller in Premium Power Park are extracted, which are verified inthe typical topology of adaptive power controller.