TWI730649B - Power conversion system and method - Google Patents
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
- H02J1/12—Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract
Description
本公開涉及一種電力變換系統及方法,特別涉及一種耦合至直流電網的電力變換系統及方法。The present disclosure relates to a power conversion system and method, and more particularly to a power conversion system and method coupled to a DC power grid.
隨著新能源發電的快速發展,各種發電及儲能系統逐步接入電網中。在接入交流電網前,需要進行長距離輸電,現有技術中多利用交流電纜進行輸電。然而,長距離的交流電纜效率較低且成本較高。此外,長距離交流電纜與大量變換器耦合,易發生寬頻域震盪,不利於系統穩定。With the rapid development of new energy power generation, various power generation and energy storage systems are gradually connected to the grid. Before being connected to the AC power grid, long-distance power transmission is required. In the prior art, AC cables are often used for power transmission. However, long-distance AC cables are less efficient and costly. In addition, long-distance AC cables are coupled with a large number of converters, which is prone to wide-band oscillations, which is not conducive to system stability.
因此,如何發展一種可改善上述現有技術的電力變換系統及方法,實為目前迫切的需求。Therefore, how to develop a power conversion system and method that can improve the above-mentioned prior art is actually an urgent need at present.
本公開的目的在於提供一種電力變換系統及方法,通過並聯耦接於直流電網的電力變換裝置,可提供高壓直流電至直流電網。此外,可依據上級控制命令來協調電力變換裝置的電能轉換操作。借此,本公開的電力變換系統及方法是採用高壓直流輸電,可降低成本並減小輸電過程中的損耗。The purpose of the present disclosure is to provide a power conversion system and method, which can provide high-voltage DC power to the DC power grid through power conversion devices coupled in parallel to the DC power grid. In addition, the power conversion operation of the power conversion device can be coordinated according to upper-level control commands. Therefore, the power conversion system and method of the present disclosure adopts high-voltage direct current transmission, which can reduce the cost and reduce the loss in the power transmission process.
為達上述目的,本公開提供一種電力變換系統,耦接於直流電網,電力變換系統包含至少一電力變換裝置及主控制器。電力變換裝置並聯耦接於直流電網,其中每一電力變換裝置包含至少一發電單元、至少一逆變單元、中頻變壓器及整流裝置。逆變單元電連接於對應的發電單元,並架構於將發電單元的輸出電壓轉換為第一交流電壓。中頻變壓器電連接於逆變單元,並將第一交流電壓升壓為第二交流電壓。整流裝置電連接於中頻變壓器及直流電網,以對第二交流電壓進行整流並輸出直流電壓。主控制器被配置為接收上級控制命令,以基於上級控制命令協調電力變換裝置的電能轉換操作。To achieve the above objective, the present disclosure provides a power conversion system coupled to a DC power grid. The power conversion system includes at least one power conversion device and a main controller. The power conversion device is coupled to the DC grid in parallel, and each power conversion device includes at least one power generation unit, at least one inverter unit, an intermediate frequency transformer, and a rectifier device. The inverter unit is electrically connected to the corresponding power generation unit, and is configured to convert the output voltage of the power generation unit into a first AC voltage. The intermediate frequency transformer is electrically connected to the inverter unit and boosts the first AC voltage to the second AC voltage. The rectifying device is electrically connected to the intermediate frequency transformer and the DC power grid to rectify the second AC voltage and output the DC voltage. The main controller is configured to receive an upper-level control command to coordinate the power conversion operation of the power conversion device based on the upper-level control command.
為達上述目的,本公開更提供一種電力變換方法,適用於電力變換系統,其中電力變換系統耦接於直流電網並包含至少一電力變換裝置及主控制器,電力變換裝置並聯耦接於直流電網,每一電力變換裝置包含至少一發電單元、至少一逆變單元、一中頻變壓器及一整流裝置。電力變換方法包含下列步驟:(a) 利用逆變單元將對應的發電單元的輸出電壓轉換為第一交流電壓;(b) 利用中頻變壓器將第一交流電壓升壓為第二交流電壓;(c) 利用整流裝置對第二交流電壓進行整流並產生直流電壓;以及(d) 利用主控制器接收上級控制命令,並基於上級控制命令協調電力變換裝置的電能轉換操作。To achieve the above objective, the present disclosure further provides a power conversion method suitable for a power conversion system, wherein the power conversion system is coupled to a DC power grid and includes at least one power conversion device and a main controller, and the power conversion device is coupled in parallel to the DC power grid Each power conversion device includes at least one power generation unit, at least one inverter unit, an intermediate frequency transformer, and a rectifier device. The power conversion method includes the following steps: (a) Use an inverter unit to convert the output voltage of the corresponding power generation unit into a first AC voltage; (b) Use an intermediate frequency transformer to boost the first AC voltage to a second AC voltage; c) Utilizing the rectifying device to rectify the second AC voltage and generating a DC voltage; and (d) Utilizing the main controller to receive upper-level control commands, and coordinate the power conversion operation of the power conversion device based on the upper-level control commands.
體現本公開特徵與優點的一些典型實施例將在後段的說明中詳細敘述。應理解的是本公開能夠在不同的實施方式上具有各種的變化,其皆不脫離本公開的範圍,且其中的說明及圖示在本質上是當作說明之用,而非架構於限制本公開。Some typical embodiments embodying the features and advantages of the present disclosure will be described in detail in the following description. It should be understood that the present disclosure can have various changes in different implementations, which do not depart from the scope of the present disclosure, and the descriptions and illustrations therein are essentially for illustrative purposes, rather than being constructed to limit the present disclosure. public.
圖1A為本公開優選實施例的電力變換系統的電路架構示意圖。如圖1A所示,電力變換系統2耦接於直流電網1,且包含至少一電力變換裝置21及主控制器20。電力變換裝置21皆並聯耦接於直流電網1。主控制器20被配置為接收上級控制指令,並基於上級控制命令協調電力變換裝置21的電能轉換操作,其中主控制器20可為例如但不限於被配置為控制電力變換裝置21的輸出功率為固定值。進一步地,上級控制命令可由上級直流電網調度中心發送給主控制器,例如功率指令,但本公開不以此為限。每一電力變換裝置21包含至少一發電單元22、至少一逆變單元23、中頻變壓器24及整流裝置25。每一逆變單元23均電連接於對應的發電單元22,逆變單元23架構於將發電單元22的輸出電壓轉換為第一交流電壓。中頻變壓器24電連接於所有逆變單元23,且架構於將每一逆變單元輸出的第一交流電壓升壓為第二交流電壓。於一些實施例中,中頻變壓器24包含多個低壓繞組及一個高壓繞組,其中低壓繞組電連接於對應的逆變單元23。整流裝置25電連接於中頻變壓器24及直流電網1,整流裝置25對第二交流電壓進行整流,並輸出高壓直流電至直流電網1。借此,本公開的電力變換系統2耦合至直流電網,可採用高壓直流輸電,降低成本並減小輸電過程中的損耗。FIG. 1A is a schematic diagram of a circuit structure of a power conversion system according to a preferred embodiment of the present disclosure. As shown in FIG. 1A, the
於一些實施例中,在任一電力變換裝置21中,逆變單元23依據中頻變壓器24的工作頻率ω而將對應的發電單元22的輸出電壓轉換為第一交流電壓,其中第一交流電壓的頻率等於中頻變壓器24的工作頻率ω。In some embodiments, in any
須注意的是,對於電力變換系統2中的電力變換裝置,電力變換裝置可為例如但不限於採用風力發電或光伏發電,例如圖2C及圖2D所示。當然,若電力變換系統2包含多個電力變換裝置中,亦可分別採用不同的發電來源,例如圖2A所示,多個電力變換裝置中可部分採用風力發電,部分採用光伏發電。以下將分別示例說明採用風力發電及光伏發電的電力變換裝置 (21a、21b) 的電路結構。It should be noted that, for the power conversion device in the
圖3A為本公開優選實施例的採用風力發電的電力變換裝置的電路結構示意圖。如圖3A所示,電力變換裝置21a採用風力發電,電力變換裝置21a的發電單元為風力發電單元22a,風力發電單元22a包括風機28和機側變換器26。電力變換裝置21a的逆變單元為網側變換器23a,電連接於機側變換器26與中頻變壓器24之間,並架構於穩定直流母線電壓及控制輸出電壓頻率。機側變換器26將風機28發出的頻率和幅值變化的交流電變換為直流電,網側變換器23a將直流電轉換為中頻三相交流電(即第一交流電壓)。中頻三相交流電經過高升壓比的中頻變壓器24升壓後得到第二交流電,最後通過不控整流裝置25將第二交流電變換為直流電並輸出至高壓直流輸電網(即直流電網1)。其中,中頻變壓器24具有高升壓比將低壓三相交流電(例如690V)升為高壓三相交流電(例如26KV),採用中頻變壓器可減小變壓器體積,降低成本。進一步地,高壓三相交流電通過一個高耐壓的不控整流裝置25轉換為直流電,本發明的整流裝置25也可採用半控器件。直流電網1的母線電壓為35KV,但本發明不以此為限。3A is a schematic diagram of a circuit structure of a power conversion device using wind power generation according to a preferred embodiment of the present disclosure. As shown in FIG. 3A, the
於一些實施例中,風力發電單元22a的輸出電壓為小於1KV的低壓或大於1KV的高壓,逆變單元對應為低壓逆變單元或高壓逆變單元。於一些實施例中,電力變換裝置21a還包含濾波器27,濾波器27電連接於網側變換器23a與中頻變壓器24之間,濾波器27是架構於對網側變換器23a的輸出電流進行濾波。In some embodiments, the output voltage of the wind
整流裝置25包含多個橋臂,本實施例中,整流裝置包含3個橋臂,每一橋臂具有節點,節點電連接於中頻變壓器24並將橋臂分為兩個支路,每一支路由多個整流元件串聯構成。借此,可降低對整流元件的耐壓性能要求。整流元件可為例如但不限於二極體或半控器件。針對直流電網1的電壓等級(例如35KV),需要選取高耐壓的二極體或半控器件,每半個橋臂由大於等於兩個的二極體或半控器件串聯構成,可降低每一整流元件的耐壓等級,降低成本。The
於一些實施例中,風機28為高壓風機(例如10KV),對應的機側變換器26和網側變換器23a為高壓變換器,如圖3B所示,機側變換器26及網側變換器23a均為多電平變換器,但亦不以此為限,借此可降低中頻變壓器24的匝比。例如,採用10KV等級的風力發電機和變流器(包括機側變換器和網側變換器),和常規的690V風力發電系統相比,選用的中頻變壓器24的匝比可降低十幾倍,針對35KV的直流輸電系統,中頻變壓器24匝比由26KV/690V降低為26KV/10KV。In some embodiments, the
此外,風力發電單元22a及逆變單元 (即網側變換器23a) 的個數並不限於一,例如於圖3C所示,電力變換裝置21a可包含兩個風力發電單元22a及兩個網側變換器23a,其中兩個網側變換器23a分別電連接於兩個風力發電單元22a,中頻變壓器24電連接於兩個網側變換器23a。於此實施例中,中頻變壓器24為雙繞組升壓變壓器,相較於採用兩個獨立變壓器分別連接於兩個網側變換器23a的方案,可有效節省成本。當然,風機28也可採用具有多輸出繞組的風機,如圖3D所示,風機28包括兩組輸出繞組,其中每一組輸出繞組電連接對應的機側變換器26,構成一個風力發電單元22a。In addition, the number of wind
為了對電力變換裝置21a中的電能轉換進行控制,其中於本實施例中,電力變換裝置21a為風力發電系統,機側變換器26控制風機28的輸出功率,網側變換器23a穩定直流母線29的母線電壓同時控制輸出的第一交流電壓的頻率,第一交流電壓的幅值由直流電網1和整流裝置25鉗位住。如圖4所示,電力變換裝置21a的逆變單元包含第一控制電路200a,第一控制電路200a依據中頻變壓器24的工作頻率ω及逆變單元的多個電信號而產生一開關信號,並通過開關信號控制逆變單元的轉換操作。第一控制電路200a包含計算器201、座標變換器202、電壓調節器203、電流調節器204及PWM (Pulse Width Modulation) 調製器205。計算器201依據中頻變壓器24的工作頻率ω產生角度信號θ,即對頻率ω積分產生角度信號。中頻頻率常規取400HZ,為中頻變壓器24的額定工作頻率,但本發明不以此為限。座標變換器202依據逆變單元 (即網側變換器23a) 的交流端的三相電流量Iabc
及角度信號θ產生有功電流Id
及無功電流Iq
。電壓調節器203採樣直流母線29的直流母線電壓Udc
,並依據直流母線電壓Udc
及其指令值Udcr
產生有功電流指令Idr
。電流調節器204依據有功電流指令Idr
、無功電流指令Iqr
、有功電流Id
、無功電流Iq
及角度信號θ產生三相控制電勢Eabc
。PWM調製器205依據三相控制電勢Eabc
產生開關信號,其中第一控制電路200a通過開關信號控制網側變換器23a的轉換操作。PWM調製器205可為例如但不限於通過SPWM (Sinusoidal PWM) 或SVPWM (Space Vector PWM) 技術產生開關信號。其中,無功電流指令通過對無功功率進行閉環調節得到。In order to control the conversion of electric energy in the
圖5A為本公開優選實施例的採用光伏發電的電力變換裝置的電路結構示意圖。如圖5A所示,電力變換裝置21b採用光伏發電,電力變換裝置21b的發電單元為光伏發電單元22b,逆變單元23b將光伏發電單元22b的輸出電壓轉換為中頻三相交流電(即第一交流電壓)。中頻三相交流電經過高升壓比的中頻變壓器24升壓後得到第二交流電,最後通過不控整流裝置25將第二交流電變換為直流電並輸出至高壓直流輸電網(即直流電網1)。其中與圖3A中類似的電路元件是以相同的標號表示,類似電路元件具有類似的功能,具體請參考上述描述,於此不再贅述。此外,光伏發電單元22b及逆變單元23b的個數並不限於一,例如於圖5B所示,電力變換裝置21b可包含兩個光伏發電單元22b及兩個逆變單元23b,其中兩個逆變單元23b分別電連接於兩個光伏發電單元22b,中頻變壓器24電連接於兩個逆變單元23b。FIG. 5A is a schematic diagram of a circuit structure of a power conversion device using photovoltaic power generation according to a preferred embodiment of the present disclosure. As shown in Figure 5A, the
為了對電力變換裝置21b中的電能轉換進行控制,其中於本實施例中,電力變換裝置21b為光伏發電系統,逆變單元23b控制輸出的第一交流電壓的頻率,第一交流電壓的幅值由直流電網1和整流裝置25鉗位住。如圖6所示,電力變換裝置21b的逆變單元23b包含第二控制電路200b,第二控制電路200b依據中頻變壓器24的工作頻率ω及逆變單元23b的多個電信號而產生一開關信號,並通過開關信號控制逆變單元23b的轉換操作。第二控制電路200b包含計算器201、座標變換器202、MPPT (Maximum power point tracking) 控制器206、電壓調節器203、電流調節器204及PWM調製器205。計算器201依據中頻變壓器24的工作頻率ω產生角度信號θ,即對頻率ω積分產生角度信號。中頻頻率常規取400HZ,為中頻變壓器24的額定工作頻率,但本發明不以此為限。座標變換器202依據逆變單元23b的交流端的三相電流量Iabc
及角度信號θ產生有功電流Id
及無功電流Iq
。MPPT控制器206獲取光伏發電單元22的輸出電壓Uo
及輸出電流Io
,並根據輸出電壓Uo
及輸出電流Io
計算直流功率,以根據MPPT演算法獲取輸出電壓指令Uor
。電壓調節器203依據光伏發電單元22b的輸出電壓Uo
及輸出電壓指令Uor
產生有功電流指令Idr
。電流調節器204依據有功電流指令Idr
、無功電流指令Iqr
、有功電流Id
、無功電流Iq
及角度信號θ產生三相控制電勢Eabc
。PWM調製器205依據三相控制電勢Eabc
產生開關信號,其中第二控制電路200b通過開關信號控制逆變單元23b的轉換操作。PWM調製器205可為例如但不限於通過SPWM (Sinusoidal PWM) 或SVPWM (Space Vector PWM) 技術調製產生開關信號。其中,無功電流指令通過對無功功率進行閉環調節得到。In order to control the conversion of electric energy in the
於一些實施例中,電力變換裝置21包括第一電力變換裝置和第二電力變換裝置,第一電力變換裝置和第二電力變換裝置並聯耦接於直流電網1。其中第一電力變換裝置為風力發電系統,第二電力變換裝置為光伏發電系統。In some embodiments, the
於一些實施例中,除電力變換裝置21之外,電力變換系統2還包含儲能裝置3,如圖1B所示,儲能裝置3與所有電力變換裝置21一同並聯耦接於直流電網1。進一步地,如圖2B所示,電力變換系統2包括採用風力發電的電力變換裝置21a、採用光伏發電的電力變換裝置21b及儲能裝置3,形成大型的風光儲混合發電系統。當然本發明不以此為限,如圖2C所示,電力系統2包括採用風力發電的電力變換裝置21a和儲能裝置3,形成風儲發電系統;如圖2D所示,電力系統2包括採用光伏發電的電力變換裝置21b和儲能裝置3,形成光儲發電系統。In some embodiments, in addition to the
基於上述各實施例及其變形,本公開提出一種高壓直流耦合系統,至少一個電力變換裝置(如風力發電裝置、光伏發電裝置)和/或儲能裝置之間獨立並聯耦接在直流電網上,方便擴展;各發電單元通過各自的逆變單元將發出的電能轉換為中頻交流電,並經過各自的升壓變壓器和整流裝置變換為高壓直流電接入高壓直流輸電網,儲能裝置通過直流變換器將低壓直流電變換為高壓直流電接入高壓直流輸電網,採用直流輸電技術將電能輸送至遠端電網或使用者端,同樣電壓等級下輸送能力更強,損耗更小;由主控制器進行統一控制,實現發電,電網調節和調度功能。Based on the foregoing embodiments and their variants, the present disclosure proposes a high-voltage DC coupling system, in which at least one power conversion device (such as a wind power generation device, a photovoltaic power generation device) and/or an energy storage device are independently coupled in parallel to the DC power grid, Convenient expansion; each power generation unit converts the generated electric energy into intermediate frequency alternating current through its own inverter unit, and converts it into high-voltage direct current through its respective step-up transformer and rectifier device to connect to the high-voltage direct current transmission grid, and the energy storage device through the DC converter Convert low-voltage direct current to high-voltage direct current and connect it to the high-voltage direct current transmission grid, and use direct current transmission technology to transmit the electric energy to the remote grid or user end. Under the same voltage level, the transmission capacity is stronger and the loss is smaller; it is controlled by the main controller. , To achieve power generation, grid regulation and dispatch functions.
圖2B示意性示出一種高壓直流耦合系統,其包含採用風力發電的電力變換裝置21a、採用光伏發電的電力變換裝置21b、儲能裝置3和主控制器20。其中電力變換裝置21a、電力變換裝置21b和儲能裝置3分別作為獨立的裝置並聯耦接於直流電網1,實現風機或者光伏發電的高壓直流輸電,並且各裝置可隨時併入直流電網1或與直流電網1斷開,方便擴展。主控制器20檢測電力變換裝置21a和電力變換裝置21b的輸出功率,並根據電網調度命令計算儲能裝置3的功率指令,以控制儲能裝置3的充放電運行,使電力變換系統2實現固定功率輸出;或者主控制器20根據上級控制命令計算儲能裝置3的功率指令,以控制儲能裝置3的充放電運行,實現削峰填谷,平滑新能源等目標。需要說明的是,上述描述僅用於示意性說明,並不構成對本公開的限制。當然,本實施例的系統可以同時包含多個風力發電裝置,多個光伏發電裝置和多個儲能裝置。2B schematically shows a high-voltage direct current coupling system, which includes a
圖2C示意性示出另一種高壓直流耦合系統,其包含採用風力發電的電力變換裝置21a、儲能裝置3和主控制器20。其中電力變換裝置21a和儲能裝置3分別作為獨立的裝置並聯耦接於直流電網1,實現風機發電的高壓直流輸電,並且各裝置可隨時併入直流電網1或與直流電網1斷開,方便擴展。主控制器20檢測電力變換裝置21a的輸出功率,並根據電網調度命令計算儲能裝置3的功率指令,以控制儲能裝置3的充放電運行,使電力變換系統2實現固定功率輸出;或者主控制器20根據上級控制命令計算儲能裝置3的功率指令,以控制儲能裝置3的充放電運行,實現削峰填谷,平滑新能源等目標。需要說明的是,上述描述僅用於示意性說明,並不構成對本公開的限制。當然,本實施例的系統可以包含多個風力發電裝置,即對應一個風力發電廠,且該風力發電裝置可以是陸上風電,也可以是海上風電。FIG. 2C schematically shows another high-voltage direct current coupling system, which includes a
圖2D示意性示出又一種高壓直流耦合系統,其包含採用光伏發電的電力變換裝置21b、儲能裝置3和主控制器20。其中電力變換裝置21b和儲能裝置3分別作為獨立的裝置並聯耦接於直流電網1,實現光伏發電的高壓直流輸電,並且各裝置可隨時併入直流電網1或與直流電網1斷開,方便擴展。主控制器20檢測光伏發電裝置21b的輸出功率,並根據電網調度命令計算儲能裝置3的功率指令,以控制儲能裝置3的充放電運行,電力變換系統2實現固定功率輸出;或者主控制器20根據上級控制命令計算儲能裝置3的功率指令,以控制儲能裝置3的充放電運行,實現削峰填谷,平滑新能源等目標。需要說明的是,上述描述僅用於示意性說明,並不構成對本公開的限制。當然,本實施例的系統可以包含多個光伏發電裝置,即對應一個光伏發電廠。FIG. 2D schematically shows another high-voltage direct current coupling system, which includes a
圖7為本公開優選實施例的儲能裝置的電路結構示意圖。如圖7所示,儲能裝置3包含多個儲能單元30,每一儲能單元30包含相連接的儲能元件31及直流變換器32,其中多個直流變換器32串聯連接以形成直流輸出端耦接至直流電網1。於此實施例中,主控制器20可為例如但不限於被配置為控制多個電力變換裝置21的輸出功率及儲能裝置3的輸出功率之和為固定值。於一些實施例中,主控制器20接收多個儲能元件31的荷電狀態,並自直流電網1接收上級控制命令,主控制器20基於上級控制命令及荷電狀態產生該多個直流變換器32的功率指令,借此可根據實際需求調整各儲能單元30的輸出功率。FIG. 7 is a schematic diagram of a circuit structure of an energy storage device according to a preferred embodiment of the present disclosure. As shown in FIG. 7, the
為了對儲能裝置3的電能轉換進行控制,於一些實施例中,如圖8所示,儲能單元30還包含第三控制電路300,第三控制電路300包含計算器301、功率調節器302、電流調節器303及PWM調製器304。計算器301依據儲能元件的電流I及電壓U計算儲能元件功率P。功率調節器302接收主控制器20提供的該儲能單元30的功率指令Pr
,依據儲能元件的功率P及功率指令Pr
產生儲能元件的電流指令Ir
。其中,主控制器20根據各儲能元件的荷電狀態分配儲能裝置總的功率指令,得到每一儲能單元的功率指令Pr
,各儲能單元根據功率指令自動分配高壓側直流電壓。電流調節器303依據儲能元件的電流I及電流指令Ir
產生直流電勢E。PWM調製器304依據直流電勢E產生開關信號,其中第三控制電路300通過開關信號控制直流變換器32的轉換操作。In order to control the electric energy conversion of the
通過設置儲能裝置3,主控制器20可通過控制儲能裝置3靈活調整電力變換系統2中的功率輸出的分配。舉例而言,主控制器20檢測電力變換裝置21的發電功率,並對發電功率進行濾波平滑處理後得到目標功率,進而將目標功率減去發電功率,並依據其差值調整儲能裝置3中各儲能單元的功率指令以控制儲能單元的充放電運作,平滑功率波動,借此使電力變換系統2的實際輸出功率與目標功率一致。此外,主控制器20可依據直流電網1的負荷需求及電力變換裝置21的發電情況進行能量調度,例如在電力變換裝置21的發電量較多且直流電網1的負荷需求較小時,可將多餘的能量存儲於儲能裝置3的儲能元件31中,而在電力變換裝置21的發電量較少且直流電網1的負荷需求較大時,則可將儲能元件31所存儲的能量釋出並供給至直流電網1。By providing the
主控制器20與每一電力變換裝置21通信,可根據直流電網1的實際需求實現不同功能。當直流電網1要求電力變換系統2輸出固定功率時,若電力變換系統2不包括儲能裝置,主控制器20檢測每一電力變換裝置21的輸出功率,對至少一電力變換裝置21進行限功率運行,以輸出目標功率至直流電網1,滿足直流電網1的實際需求;若電力變換系統2包括儲能裝置3,主控制器20檢測每一電力變換裝置21的輸出功率,如光伏發電裝置和/或風力發電裝置的輸出功率,固定功率輸出的目標功率減去電力變換裝置21的輸出功率,得到儲能裝置3的功率指令,根據儲能元件31的荷電狀態將儲能裝置3的功率指令分配給每一儲能單元30,通過控制儲能裝置3的充放電運行實現固定功率輸出。The
於一些實施例,主控制器20檢測風力發電裝置和/或光伏發電裝置的發電功率,通過儲能裝置3對此功率進行濾波平滑處理,具體地,平滑後的目標功率減去實際發電功率,得到需要儲能裝置3平滑的波動的功率指令。 於一些實施例,主控制器20根據電網調度和各發電裝置發電情況,控制儲能裝置3實現能量時移,例如當發電裝置發出的電能較多而需求較小時,將能量存儲在儲能元件31中;當發電裝置發出的電能較少而需求較大時,將儲能元件31中的能量輸出,滿足實際需求。In some embodiments, the
圖9為本公開優選實施例的電力變換方法的步驟示意圖。電力變換方法可適用於圖1A及圖1B所示的電力變換系統2中。如圖9所示,電力變換方法包含下列步驟S1、S2、S3及S4。Fig. 9 is a schematic diagram of steps of a power conversion method according to a preferred embodiment of the present disclosure. The power conversion method can be applied to the
於步驟S1中,利用逆變單元23將對應的發電單元22的輸出電壓轉換為第一交流電壓。於一些實施例中,逆變單元23是依據中頻變壓器24的工作頻率ω將對應的發電單元22的輸出電壓轉換為第一交流電壓,其中第一交流電壓的頻率等於工作頻率ω。In step S1, the
於步驟S2中,利用中頻變壓器24將第一交流電壓升壓為第二交流電壓。In step S2, the
於步驟S3中,利用整流裝置25對第二交流電壓進行整流並產生直流電壓。In step S3, the rectifying
於步驟S4中,利用主控制器20接收上級控制命令,並基於上級控制命令協調多個電力變換裝置21的電能轉換操作。於一些實施例中,是利用主控制器20控制多個電力變換裝置21的輸出功率為固定值。於另一些實施例中,是利用主控制器20控制多個電力變換裝置21的輸出功率及儲能裝置3的輸出功率之和為固定值。In step S4, the
於一些實施例中,為了對採用風力發電的電力變換裝置21a進行控制,電力變換方法還包含下列步驟。首先,依據中頻變壓器24的工作頻率ω產生角度信號θ。接著,依據風力發電單元22a所對應的逆變單元 (即網側變換器23a) 的交流端的三相電流量Iabc
及角度信號θ產生有功電流Id
及無功電流Iq
。接著,採樣直流母線29的母線電壓Udc
,並依據直流母線電壓Udc
及其指令值Udcr
產生有功電流指令Idr
。而後,依據有功電流指令Idr
、無功電流指令Iqr
、有功電流Id
、無功電流Iq
及角度信號θ產生三相控制電勢Eabc
。最後,依據三相控制電勢Eabc
產生開關信號,並通過開關信號控制風力發電單元22a所對應的逆變單元 (即網側變換器23a) 的運行。In some embodiments, in order to control the
於一些實施例中,為了對採用光伏發電的電力變換裝置21b進行控制,電力變換方法還包含下列步驟。首先,依據中頻變壓器24的工作頻率ω產生角度信號θ。接著,依據光伏發電單元22b所對應的逆變單元23b的交流端的三相電流量Iabc
及角度信號θ產生有功電流Id
及無功電流Iq
。接著,獲取光伏發電單元22的輸出電壓Uo
及輸出電流Io
,並根據輸出電壓Uo
及輸出電流Io
計算直流功率,並根據MPPT演算法獲取輸出電壓指令Uor
。接著,依據光伏發電單元22b的輸出電壓Uo
及輸出電壓指令Uor
產生有功電流指令Idr
。而後,依據有功電流指令Idr
、無功電流指令Iqr
、有功電流Id
、無功電流Iq
及角度信號θ產生三相控制電勢Eabc
。最後,依據三相控制電勢Eabc
產生開關信號,並通過開關信號控制光伏發電單元22b所對應的逆變單元23b的運行。In some embodiments, in order to control the
於一些實施例中,為了對儲能裝置3進行控制,電力變換方法還包含下列步驟。首先,依據儲能元件電流I及電壓U計算儲能元件功率P。接著,接收主控制器20提供的該儲能單元30的功率指令Pr
,依據儲能元件的功率P及功率指令Pr
產生儲能元件的電流指令Ir
。而後,依據儲能元件的電流I及電流指令Ir
產生直流電勢E。最後,依據電勢E產生開關信號,並通過開關信號控制直流變換器32的運行。In some embodiments, in order to control the
綜上所述,本公開提供一種電力變換系統及方法,通過並聯耦接於直流電網的至少一電力變換裝置,可提供高壓直流電至直流電網。此外,可依據直流電網的上級控制命令來協調多個電力變換裝置的電能轉換操作。借此,本公開的電力變換系統及方法是採用高壓直流輸電,可降低成本並減小輸電過程中的損耗。再者,通過設置儲能裝置,主控制器可通過控制儲能裝置靈活調整電力變換系統中的功率輸出的分配,實現控制目標。更甚者,主控制器可依據直流電網的供給負荷及電力變換裝置的發電情況進行能量調度,例如在電力變換裝置的發電量較多且直流電網的供給負荷較小時,可將多餘的能量存儲於儲能裝置的儲能元件中,而在電力變換裝置的發電量較少且直流電網的供給負荷較大時,則可將儲能元件所存儲的能量釋出而供給予直流電網。In summary, the present disclosure provides a power conversion system and method, which can provide high-voltage DC power to the DC power grid through at least one power conversion device coupled in parallel to the DC power grid. In addition, the power conversion operations of multiple power conversion devices can be coordinated according to the upper-level control commands of the DC grid. Therefore, the power conversion system and method of the present disclosure adopts high-voltage direct current transmission, which can reduce the cost and reduce the loss in the power transmission process. Furthermore, by setting the energy storage device, the main controller can flexibly adjust the distribution of power output in the power conversion system by controlling the energy storage device to achieve the control target. What's more, the main controller can perform energy dispatch according to the supply load of the DC grid and the power generation situation of the power conversion device. For example, when the power conversion device has a large amount of power generation and the supply load of the DC grid is small, the excess energy can be It is stored in the energy storage element of the energy storage device, and when the power conversion device generates less power and the supply load of the DC grid is large, the energy stored in the energy storage element can be released and supplied to the DC grid.
須注意,上述僅是為說明本公開而提出的優選實施例,本公開不限於所述的實施例,本公開的範圍由申請專利範圍決定。且本公開得由熟習此技術的人士任施匠思而為諸般修飾,然皆不脫申請專利範圍所欲保護者。It should be noted that the foregoing are only preferred embodiments proposed for explaining the present disclosure, and the present disclosure is not limited to the described embodiments, and the scope of the present disclosure is determined by the scope of the patent application. Moreover, the present disclosure can be modified in many ways by those who are familiar with this technology, but it does not deviate from those who wish to protect the scope of the patent application.
1:直流電網
2:電力變換系統
20:主控制器
21、21a、21b:電力變換裝置
22:發電單元
22a:風力發電單元
22b:光伏發電單元
23、23b:逆變單元
23a:網側變換器
24:中頻變壓器
25:整流裝置
26:機側變換器
27:濾波器
28:風機
29:直流母線
200a:第一控制電路
200b:第二控制電路
201:計算器
202:座標變換器
203:電壓調節器
204:電流調節器
205:PWM調製器
206:MPPT控制器
3:儲能裝置
30:儲能單元
31:儲能元件
32:直流變換器
300:第三控制電路
301:計算器
302:功率調節器
303:電流調節器
304:PWM調製器
ω:工作頻率
θ:角度信號
Iabc:三相電流量
Id:有功電流
Idr:有功電流指令
Iq:無功電流
Iqr:無功電流指令
Uo:輸出電壓
Udc:直流母線電壓
Udcr:指令值
Io:輸出電流
I:電流
U:電壓
P:功率
Pr:功率指令
Eabc、E:電勢1: DC grid 2: Power conversion system 20:
圖1A為本公開優選實施例的電力變換系統的電路架構示意圖。FIG. 1A is a schematic diagram of a circuit structure of a power conversion system according to a preferred embodiment of the present disclosure.
圖1B為本公開另一優選實施例的電力變換系統的電路架構示意圖。FIG. 1B is a schematic diagram of a circuit structure of a power conversion system according to another preferred embodiment of the present disclosure.
圖2A為圖1A的電力變換系統的變化例的電路架構示意圖。FIG. 2A is a schematic diagram of a circuit structure of a variation of the power conversion system of FIG. 1A.
圖2B、圖2C及圖2D為圖1B的電力變換系統的變化例的電路架構示意圖。FIG. 2B, FIG. 2C, and FIG. 2D are schematic diagrams of the circuit structure of a modification of the power conversion system of FIG.
圖3A為本公開優選實施例的採用風力發電的電力變換裝置的電路結構示意圖。3A is a schematic diagram of a circuit structure of a power conversion device using wind power generation according to a preferred embodiment of the present disclosure.
圖3B、圖3C及圖3D為圖3A的電力變換裝置的變化例的電路結構示意圖。3B, 3C, and 3D are schematic diagrams of the circuit structure of a modified example of the power conversion device of FIG. 3A.
圖4為圖3A的電力變換裝置及其控制電路的電路結構示意圖。4 is a schematic diagram of the circuit structure of the power conversion device and its control circuit of FIG. 3A.
圖5A為本公開優選實施例的採用光伏發電的電力變換裝置的電路結構示意圖。FIG. 5A is a schematic diagram of a circuit structure of a power conversion device using photovoltaic power generation according to a preferred embodiment of the present disclosure.
圖5B為圖5A的電力變換裝置的變化例的電路結構示意圖。FIG. 5B is a schematic diagram of a circuit structure of a modification of the power conversion device of FIG. 5A.
圖6為圖5A的電力變換裝置及其控制電路的電路結構示意圖。6 is a schematic diagram of the circuit structure of the power conversion device and its control circuit of FIG. 5A.
圖7為本公開優選實施例的儲能裝置的電路結構示意圖。FIG. 7 is a schematic diagram of a circuit structure of an energy storage device according to a preferred embodiment of the present disclosure.
圖8為圖7的儲能裝置及其控制電路的電路結構示意圖。FIG. 8 is a schematic diagram of the circuit structure of the energy storage device and its control circuit of FIG. 7.
圖9為本公開優選實施例的電力變換方法的步驟示意圖。Fig. 9 is a schematic diagram of steps of a power conversion method according to a preferred embodiment of the present disclosure.
1:直流電網 1: DC grid
2:電力變換系統 2: Power conversion system
20:主控制器 20: main controller
21:電力變換裝置 21: Power conversion device
22:發電單元 22: power generation unit
23:逆變單元 23: Inverter unit
24:中頻變壓器 24: Intermediate frequency transformer
25:整流裝置 25: Rectifier
Claims (22)
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CN111355256A (en) * | 2020-03-09 | 2020-06-30 | 台达电子企业管理(上海)有限公司 | High-voltage direct-current power transformation device, power system and control method of power system |
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