CN113890105B - 基于最大电压点跟踪的并联逆变器同步控制方法 - Google Patents
基于最大电压点跟踪的并联逆变器同步控制方法 Download PDFInfo
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/40—Synchronising a generator for connection to a network or to another generator
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
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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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
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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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
- H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
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- Y02E10/00—Energy generation through renewable energy sources
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- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
基于最大电压点跟踪的并联逆变器同步控制方法,包括以下步骤:步骤1:当新的逆变器投入时,通过扰动观察法改变新投入的逆变器的相位,实现对负载电压的最大电压点跟踪;步骤2:当连续多次检测到负载电压的幅值发生来回波动时,表明新投入的逆变器同步操作已完成,此时新投入逆变器退出最大电压点跟踪控制切换为定频率控制。相比于传统锁相环,本发明中最大电压点跟踪方法中每台逆变器的地位相同,任意一台逆变器的退出都不会影响系统的正常运行,提高了系统的可靠性。
Description
技术领域
本发明涉及逆变器并联运行控制技术领域,具体涉及一种基于最大电压点跟踪的并联逆变器同步控制方法。
背景技术
高比例可再生能源发电与高比例电力电子装备正在改变电力系统的形态。随着可再生能源发电占比的提高,一定区域内可再生能源超过70%的超高比例,甚至达100%的全可再生能源发电场景变为现实。对于以可再生能源为主体的电力系统,多台逆变器通过协调控制支撑电力系统的电压和频率是提高可再生能源渗透率的关键技术。
目前逆变器并联运行控制策略主要包括集中控制、主从控制、下垂控制。其中:1)、集中控制通过公共总线对各逆变器进行统一控制,公共模块故障将导致系统崩溃,可靠性不高。2)、主从控制以一台逆变器作为主控单元,采用电压电流双闭环控制,并通过通信线将电流指令发送至其余逆变器,但通信线的存在也将降低系统的可靠性。3)、下垂控制则无需通信线,每台逆变器根据自身信息量进行控制,可靠性较高,但是由于引入了功率量,导致控制系统呈现非线性,稳定性较差。此外,下垂特性也会导致固有的频率偏差。基于虚拟阻抗法的下垂控制能有效改善传统下垂控制的缺点,但这种方法需要各逆变器相位保持同步。
目前,逆变器的相位同步多通过锁相环实现,但基于锁相环的同步方法要求主逆变器提供参考相位,一旦主逆变器因故障退出运行,其它逆变器也将无法正常工作。同样的,基于通信的同步方法也同样存在可靠性较差的问题,且投资成本更高。
发明内容
为解决上述技术问题,本发明提供一种基于最大电压点跟踪的并联逆变器同步控制方法,相比于传统锁相环,本发明中最大电压点跟踪方法中每台逆变器的地位相同,任意一台逆变器的退出都不会影响系统的正常运行,提高了系统的可靠性。
本发明采取的技术方案为:
基于最大电压点跟踪的并联逆变器同步控制方法,包括以下步骤:
步骤1:当新的逆变器投入时,通过扰动观察法改变新投入的逆变器的相位,实现对负载电压的最大电压点跟踪;
步骤2:当连续多次检测到负载电压的幅值发生来回波动时,表明新投入的逆变器同步操作已完成,此时新投入逆变器退出最大电压点跟踪控制切换为定频率控制。
所述步骤1包括以下步骤:
步骤1.1:首先,在k-1时刻测量负载电压的幅值为U0(k-1);
步骤1.3:比较U0(k)与U0(k-1),若U0(k)≥U0(k-1),表明扰动方向正确,继续保持同方向扰动使U0(k)趋向于进一步增大;若U0(k)<U0(k-1),则施加反方向扰动使U0(k)趋向于增大;
步骤1.4:重复步骤1.3,不断调整新投入的逆变器的相位,负载电压将不断向最大电压点逼近,使新投入的逆变器与已投入的逆变器进行同步。
所述步骤2中,当连续5次检测到负载电压U0(k)=U0(k-2)时,确认同步操作已完成,此时新投入逆变器退出最大电压点跟踪控制,切换为定频率控制。
本发明一种基于最大电压点跟踪的并联逆变器同步控制方法,技术效果如下:
1)相比于锁相环,本发明同步控制方法中每台逆变器均采用定频率控制,所以任意逆变器的退出,都不会影响其它逆变器的正常运行,可靠性高。
2)由于各逆变器均采用定频率控制,所以逆变器输出电压的频率固定为50Hz,消除了传统功率下垂控制的固有频率偏差问题,极大地提高了电能质量。
3)由扰动观察法的控制思路可以看出,扰动观察法具有简单直接的优点,便于在数字控制系统中进行编程实现。
附图说明
图1为逆变器并联运行等效电路图。
图2为逆变器同步控制流程图。
图3为逆变器同步过程相位控制框图。
图4为逆变器定频率控制框图。
具体实施方式
基于最大电压点跟踪的并联逆变器同步控制方法,使用最大电压点跟踪方法,使各换流器的相位保持一致。所述最大电压点跟踪方法的理论依据为:当且仅当各逆变器输出电压的相位相同时,负载电压的幅值取得最大值。因此提出了基于扰动观察法的最大电压点跟踪方法,以实现各并联运行逆变器的同步。
具体包括以下步骤:
步骤1:当新的逆变器投入时,通过扰动观察法改变新投入的逆变器的相位,实现对负载电压的最大电压点跟踪;
所述步骤1包括以下步骤:
步骤1.1:首先,在k-1时刻测量负载电压的幅值为U0(k-1);
步骤1.3:比较U0(k)与U0(k-1),若U0(k)≥U0(k-1),表明扰动方向正确,继续保持同方向扰动使U0(k)趋向于进一步增大;若U0(k)<U0(k-1),则施加反方向扰动使U0(k)趋向于增大;
步骤1.4:重复步骤1.3,不断调整新投入的逆变器的相位,负载电压将不断向最大电压点逼近,使新投入的逆变器与已投入的逆变器进行同步。
步骤2:当连续多次检测到负载电压的幅值发生来回波动时,表明新投入的逆变器同步操作已完成,此时新投入逆变器退出最大电压点跟踪控制切换为定频率控制。具体是:当连续5次检测到负载电压U0(k)=U0(k-2)时,确认同步操作已完成,此时新投入逆变器退出最大电压点跟踪控制,切换为定频率控制。
实施例:
图1为多逆变器并联运行的等效电路图。其中:为负载电压,为所有已同步逆变器的等效电压,为新投入的逆变器的电压,为已同步的第i(i=3,4,5,…,n)台逆变器的电压,Ri为各逆变器所对应的虚拟电阻,RL、LL为分别为负载电阻和负载电容。
设R1:R2=k,代入上式可简化得:
图2为逆变器同步控制流程图。当新的逆变器投入运行时,首先,通过逆变器的控制系统判断计数变量Count≥5确认是否完成了同步,Count为设置的计数变量,如果是,则结束同步控制,切换为如图4所示定频率控制,如果否,则再通过判断U0(k)=U0(k-2)确定是否已经进入了电压来回波动阶段,如果是,那么Count++,如果否,那么对Count进行清零。接着,通过扰动观察法改变新投入的逆变器的相位,若U0(k)≥U0(k-1),表明扰动方向正确,继续保持同方向扰动,并将扰动量叠加在原有的相位基础上,即令φ(k)=φ(k-1)+2π·f0Δt+Δφ=2π·f0·t(k-1),其中:f0为工频,取50Hz,Δt为中断周期,一般设为0.1ms。反之,若U0(k)<U0(k-1),则施加反方向扰动。
图3为逆变器同步过程相位控制框图。其对应的控制方程为:
φ(k)=φ(k-1)+2π·f0Δt+Δφ。
图4为逆变器定频率控制框图,其对应的控制方程为:
φ(k)=φ(k-1)+2π·f0Δt。
Claims (4)
1.基于最大电压点跟踪的并联逆变器同步控制方法,其特征在于包括以下步骤:
步骤1:当新的逆变器投入时,通过扰动观察法改变新投入的逆变器的相位,实现对负载电压的最大电压点跟踪;
步骤1包括以下步骤:
步骤1.1:首先,在k-1时刻测量负载电压的幅值为U0(k-1);
步骤1.3:比较U0(k)与U0(k-1),若U0(k)≥U0(k-1),表明扰动方向正确,继续保持同方向扰动使U0(k)趋向于进一步增大;若U0(k)<U0(k-1),则施加反方向扰动使U0(k)趋向于增大;
步骤1.4:重复步骤1.3,不断调整新投入的逆变器的相位,负载电压将不断向最大电压点逼近,使新投入的逆变器与已投入的逆变器进行同步;
步骤2:当连续多次检测到负载电压的幅值发生来回波动时,表明新投入的逆变器同步操作已完成,此时新投入逆变器退出最大电压点跟踪控制切换为定频率控制。
2.根据权利要求1所述基于最大电压点跟踪的并联逆变器同步控制方法,其特征在于:所述步骤2中,当连续5次检测到负载电压U0(k)=U0(k-2)时,确认同步操作已完成,此时新投入逆变器退出最大电压点跟踪控制,切换为定频率控制。
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