模塊化多電平整流器優(yōu)化控制策略研究
發(fā)布時間：2018-09-08 10:04
【摘要】：隨著現(xiàn)代文明對電能需求的增加,電能變換裝置的研究變得越來越重要。電壓源型變換器經(jīng)歷了兩電平至多電平的發(fā)展階段。相對于兩電平變換器,多電平變換器具備更好的基波特性、較低的開關(guān)頻率與器件耐壓要求。模塊化多電平變換器在多電平變換器家族中具有舉足輕重的地位,其模塊化的設(shè)計方法、易于功率和電壓等級擴(kuò)展等優(yōu)點吸引了國內(nèi)外學(xué)者的廣泛關(guān)注。本文以模塊化多電平整流器(Modular Multilevel Rectifier,MMR)為研究對象,分別研究了其在電網(wǎng)平衡與不平衡情況下的工作原理,并提出了改進(jìn)系統(tǒng)控制策略的方法。系統(tǒng)啟動時,如果子模塊電容電壓值低于安全工作時電壓值,將會引起較大的沖擊電流,造成功率開關(guān)器件與電容器的損壞。本文推導(dǎo)了不控充電方式下子模塊電容電壓的表達(dá)式,指出了不控充電方式存在子模塊電容電壓穩(wěn)定值受網(wǎng)側(cè)線電壓峰值與橋臂子模塊個數(shù)限制的缺點,并提出了一種選擇充電方法。為避免傳統(tǒng)的模型預(yù)測控制(Model Predictive Control,MPC)策略權(quán)重因子的參數(shù)調(diào)節(jié)困難與遍歷尋優(yōu)復(fù)雜等問題,本文提出了一種優(yōu)化模型預(yù)測控制策略(Optimized Model Predictive Control,OMPC)。該控制策略在每個計算周期,無需借助價值函數(shù)即可得到最優(yōu)的子模塊導(dǎo)通個數(shù)。因此,很大程度上降低了控制器的設(shè)計難度與運(yùn)算量。借助MMR數(shù)學(xué)模型,推導(dǎo)了橋臂電壓與相電流、環(huán)流實際值及其參考值的關(guān)系。借助最近電平逼近或模塊統(tǒng)一脈寬調(diào)制策略確定子模塊導(dǎo)通個數(shù)與占空比,通過排序均壓策略維持子模塊電容電壓穩(wěn)定。針對理想電網(wǎng)情況,建立了MMR的數(shù)學(xué)模型,并基于此研究了傳統(tǒng)雙閉環(huán)控制策略控制器參數(shù)的設(shè)計方法。用優(yōu)化模型預(yù)測控制策略取代傳統(tǒng)的電流內(nèi)環(huán)前饋解耦控制器,降低了電流內(nèi)環(huán)控制器參數(shù)調(diào)節(jié)的復(fù)雜性,提高了電流內(nèi)環(huán)的動態(tài)性能。針對非理想電網(wǎng)情況,建立了MMR的數(shù)學(xué)模型,介紹了基于信號延時法的正負(fù)序分離方法。對抑制直流側(cè)有功功率波動與抑制交流電流不平衡兩個控制目標(biāo)分別提出了基于優(yōu)化模型預(yù)測控制的電網(wǎng)不平衡控制方法。方法的有效性通過軟件仿真與物理實驗得到了驗證。
[Abstract]:With the increasing demand of modern civilization, the research of power conversion devices becomes more and more important. The voltage source converter has experienced the development of two-level maximum level converter. Compared with the two-level converter, the multilevel converter has better fundamental characteristics, lower switching frequency and device voltage requirements. Modularized multilevel converters play an important role in the multilevel converter family. The advantages of modularized design method, easy to extend power and voltage levels have attracted wide attention of scholars at home and abroad. In this paper, the principle of modularized multilevel rectifier (Modular Multilevel Rectifier,MMR) under the condition of power network balance and unbalance is studied, and the method of improving system control strategy is put forward. When the system starts up, if the capacitance voltage of the sub-module is lower than the voltage value of the safe operation, it will cause a large impulse current, resulting in the damage of power switch devices and capacitors. In this paper, the expression of capacitor voltage of submodule in uncontrolled charging mode is derived. It is pointed out that the voltage stability of submodule capacitance is limited by the peak voltage of line voltage on the grid side and the number of submodules on the bridge arm. A selective charging method is proposed. In order to avoid the difficulty of parameter adjustment and ergodic optimization in the traditional model predictive control (Model Predictive Control,MPC) strategy, an optimized model predictive control strategy (Optimized Model Predictive Control,OMPC) is proposed in this paper. The optimal number of submodules can be obtained without the help of the value function in each calculation period of the control strategy. Therefore, to a large extent, the controller design difficulty and operation. Based on the MMR mathematical model, the relationship between the voltage of the bridge arm and the phase current, the actual value of the circulation and its reference value is derived. The number and duty cycle of the submodule are determined by using the nearest level approximation or the uniform pulse width modulation strategy, and the capacitor voltage stability of the sub-module is maintained by the sort voltage equalization strategy. In this paper, the mathematical model of MMR is established for the ideal power network. Based on this, the design method of the parameters of the traditional double-closed-loop control strategy controller is studied. The optimization model predictive control strategy is used to replace the traditional current inner loop feedforward decoupling controller, which reduces the complexity of adjusting the parameters of the current inner loop controller and improves the dynamic performance of the current inner loop. In this paper, the mathematical model of MMR is established for the non-ideal power network, and the method of positive and negative sequence separation based on signal delay method is introduced. To suppress the active power fluctuation of DC side and to suppress the imbalance of AC current, the optimal model predictive control method is proposed for the unbalanced control of power grid. The effectiveness of the method is verified by software simulation and physical experiments.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM461
[Abstract]:With the increasing demand of modern civilization, the research of power conversion devices becomes more and more important. The voltage source converter has experienced the development of two-level maximum level converter. Compared with the two-level converter, the multilevel converter has better fundamental characteristics, lower switching frequency and device voltage requirements. Modularized multilevel converters play an important role in the multilevel converter family. The advantages of modularized design method, easy to extend power and voltage levels have attracted wide attention of scholars at home and abroad. In this paper, the principle of modularized multilevel rectifier (Modular Multilevel Rectifier,MMR) under the condition of power network balance and unbalance is studied, and the method of improving system control strategy is put forward. When the system starts up, if the capacitance voltage of the sub-module is lower than the voltage value of the safe operation, it will cause a large impulse current, resulting in the damage of power switch devices and capacitors. In this paper, the expression of capacitor voltage of submodule in uncontrolled charging mode is derived. It is pointed out that the voltage stability of submodule capacitance is limited by the peak voltage of line voltage on the grid side and the number of submodules on the bridge arm. A selective charging method is proposed. In order to avoid the difficulty of parameter adjustment and ergodic optimization in the traditional model predictive control (Model Predictive Control,MPC) strategy, an optimized model predictive control strategy (Optimized Model Predictive Control,OMPC) is proposed in this paper. The optimal number of submodules can be obtained without the help of the value function in each calculation period of the control strategy. Therefore, to a large extent, the controller design difficulty and operation. Based on the MMR mathematical model, the relationship between the voltage of the bridge arm and the phase current, the actual value of the circulation and its reference value is derived. The number and duty cycle of the submodule are determined by using the nearest level approximation or the uniform pulse width modulation strategy, and the capacitor voltage stability of the sub-module is maintained by the sort voltage equalization strategy. In this paper, the mathematical model of MMR is established for the ideal power network. Based on this, the design method of the parameters of the traditional double-closed-loop control strategy controller is studied. The optimization model predictive control strategy is used to replace the traditional current inner loop feedforward decoupling controller, which reduces the complexity of adjusting the parameters of the current inner loop controller and improves the dynamic performance of the current inner loop. In this paper, the mathematical model of MMR is established for the non-ideal power network, and the method of positive and negative sequence separation based on signal delay method is introduced. To suppress the active power fluctuation of DC side and to suppress the imbalance of AC current, the optimal model predictive control method is proposed for the unbalanced control of power grid. The effectiveness of the method is verified by software simulation and physical experiments.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM461
【參考文獻(xiàn)】
相關(guān)期刊論文 前10條
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