本文選題：分布式電源 + 光伏發(fā)電��； 參考：《西南交通大學》2014年碩士論文

【摘要】：能源匱乏、環(huán)境污染以及電力需求增長給新能源分布式發(fā)電帶來良好的發(fā)展契機。而在分布式發(fā)電系統(tǒng)中增加儲能裝置,能使其利用潛力更大,不僅能夠為負載不間斷供電,也可以更好的滲透于大電網(wǎng)中。合理有效的分布式電源控制技術是實現(xiàn)分布式電源與大電網(wǎng)并網(wǎng)發(fā)電的關鍵,成為近些年研究的熱點。 本文首先闡述光伏發(fā)電和蓄電池儲能系統(tǒng)原理和特性。以并網(wǎng)逆變器作為分布式電源并網(wǎng)接口方式,研究兩種控制策略：PQ控制和下垂控制,介紹其原理,并在Simulink中搭建模型進行仿真驗證。 其次,研究了前級電源光伏-蓄電池發(fā)電系統(tǒng)。針對光伏組網(wǎng)單元直流側(cè)蓄電池雙向DC/DC變換器研究了兩種控制方法：功率外環(huán)電流內(nèi)環(huán)和電壓外環(huán)電流內(nèi)環(huán),并在模擬光照強度變化情況下進行仿真對比,結果表明功率外環(huán)電流內(nèi)環(huán)能精準控制蓄電池輸出功率,但不能直接控制直流母線電壓,會隨著能量波動而波動；而電壓外環(huán)電流內(nèi)環(huán)能直接對直流母線電壓進行控制,利用直流母線電壓高低來間接控制輸出功率,更符合分布式光伏發(fā)電系統(tǒng)的實際應用,有效防止非計劃性孤島等情況,確保逆變器輸出穩(wěn)定。驗證了通過蓄電池的充放電控制,能平抑光伏電池輸出波動,保證逆變器前端直流母線電壓很好地穩(wěn)定在額定值。 再次,設計了改進型的下垂控制。針對傳統(tǒng)的V-Q下垂控制因未考慮線路壓降情況導致無功分配有不準確、以及采用下垂控制造成的系統(tǒng)電壓頻率的誤差,對下垂控制算法進行改進,通過引入線路壓降和頻率電壓算法恢復有效地改善了無功分配不準和電壓頻率偏離額定值的情況。 最后,將光-儲系統(tǒng)接入微電網(wǎng)運行,搭建微電網(wǎng)仿真模型,研究其運行特性和控制策略。針對并網(wǎng)孤島運行兩種模式的平滑切換,研究了單模式和雙模式控制策略,并各自進行仿真算例與對比。在PQ-Droop切換控制下,分析切換過程中波動振蕩較大的原因,當DG提供的功率無法滿足負荷所需,功率差額較大,無法平滑切換的情況,為保證對重要負荷的不間斷供電,需切除次要負荷動作,研究了切負荷方法,比較一次切負荷和分開切負荷對于降低切換暫態(tài)振蕩的效果。結果表明分開切負荷能有效降低暫態(tài)振蕩,使得平穩(wěn)過渡并穩(wěn)定運行于孤島運行模式。
[Abstract]:Lack of energy, environmental pollution and the growth of electricity demand bring a good opportunity for new energy distributed generation.Adding energy storage device to distributed generation system can make it use more potential, not only can supply the load uninterruptedly, but also can penetrate into the large power grid better.Reasonable and effective distributed power generation control technology is the key to realize the grid generation of distributed generation and large power grid, and has become a hot research topic in recent years.In this paper, the principle and characteristics of photovoltaic power generation and battery energy storage system are described.Using grid-connected inverter as the interface of distributed power supply, this paper studies two control strategies: PQ control and droop control, introduces its principle, and builds a model in Simulink for simulation.Secondly, the photovoltaic-battery power generation system is studied.In this paper, two control methods for DC side battery bidirectional DC/DC converter with photovoltaic cells are studied: the power outer loop current inner loop and the voltage outer current current inner loop, and the simulation results are compared under the condition of simulated illumination intensity change.The results show that the power outer loop current inner loop can accurately control the battery output power, but can not directly control the DC bus voltage, which will fluctuate with the energy fluctuation, and the voltage outer loop current inner loop can directly control the DC bus voltage.The use of DC bus voltage to indirectly control the output power is more in line with the practical application of distributed photovoltaic power generation system. It can effectively prevent unplanned isolated islands and ensure the output stability of the inverter.It is verified that the voltage fluctuation of photovoltaic cell can be suppressed by the charge and discharge control of battery and the voltage of DC bus at the front end of inverter can be stabilized at the rated value.Thirdly, the improved droop control is designed.In view of the inaccurate reactive power distribution caused by the traditional V-Q droop control without considering the voltage drop of the line, and the error of voltage frequency caused by the sagging control, the sagging control algorithm is improved.By introducing line voltage drop and frequency voltage algorithm, we can effectively improve the situation of inaccurate reactive power distribution and voltage frequency deviation from the rated value.Finally, the optical-storage system is connected to the micro-grid to run, and the simulation model of the micro-grid is built, and its operation characteristics and control strategy are studied.Aiming at the smooth switching between two modes of grid-connected islanding operation, the control strategies of single mode and double mode are studied, and the simulation examples are given and compared with each other.Under the PQ-Droop switching control, the reasons for the large fluctuation and oscillation in the switching process are analyzed. When the power provided by DG cannot meet the needs of the load, the power difference is large, and the switching can not be smooth. In order to ensure the uninterrupted power supply to the important load,The method of load shedding is studied to compare the effect of primary and separate load shedding on the reduction of switching transient oscillation.The results show that separation of load shedding can effectively reduce transient oscillation and make steady transition and stable operation in isolated island operation mode.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM615;TM912

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