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太阳能光伏储能系统3种的主要模式

返回列表 来源: 一点零碳新能源 发布日期: 2022.06.15 浏览次数:

储能系统在光伏电站中的作用


1

保证系统稳定

光伏电站系统中,光伏输出功率曲线与负荷曲线存在较大差异,而且均有不可预料的波动特性,通过储能系统的能量存储和缓冲使得系统即使在负荷迅速波动的情况下仍然能够运行在一个稳定的输出水平。 


2

能量备用

储能系统可以在光伏发电不能正常运行的情况下起备用和过渡作用,如在夜间或者阴雨天电池方阵不能发电时,这时储能系统就起备用和过渡作用,其储能容量的多少取决于负荷的需求。 


3

提高电力品质和可靠性

储能系统还可防止负载上的电压尖峰、电压下跌和其他外界干扰所引起的电网波动对系统造成大的影响,采用足够多的储能系统可以保证电力输出的品质与可靠性。 


No.2

储能系统的主要模式


1

配置在电源直流侧的储能系统

配置在电源直流侧的储能系统主要可安装在诸如光伏发电的直流系统中,这种设计可将蓄电池组合光伏发电阵列在逆变器直流段进行配接调控,如图1。该系统中的光伏发电系统和蓄电池储能系统共享一个逆变器,但是由于蓄电池的充放电特性和光伏发电阵列的输出特性差异较大,原系统中的光伏并网逆变器中的最大功率跟踪系统(MPPT)是专门为了配合光伏输出特性设计的,无法同时满足储能蓄电池的输出特性曲线。因此,此类系统需要对原系统逆变器进行改造或重新设计制造,不仅需要使逆变器能满足光伏阵列的逆变要求,还需要增加对蓄电池组的充放电控制器,和蓄电池能量管理等功能。一般而言,该系统是单向输出的,也就是说该系统中的蓄电池是完全依靠光伏发电充电的,电网的电力是不能给蓄电池充电的。


图片

图1、配置在电源直流侧的储能系统


该系统光伏发电阵列发出的电力在逆变器前端就与蓄电池进行了自动直流平衡,这种模式的主要特点是系统效率高,电站发电出力可由光伏电站内部调度,可以达到无缝连接,输出电能质量好,输出波动非常小等,可大大提高光伏发电输出的平滑、稳定性和可调控性能,缺点是使用的逆变器需要特殊设计,不适用于对现有已经安装好的大部分光伏电站进行升级改造。另一个缺点是,该储能系统中的蓄电池组只能接受本发电单元的电力为其充电,而其他临近的光伏发电单元或电站的多余电力无法为其充电。也就是说这种方案缺乏大电站内部电力调配的功能。



2

配置在电源交流侧的储能系统


配置在电源交流侧的储能系统也可以称之为配置在交流侧的储能系统,单元型交流侧的储能的模式如图2所示,它采用单独的充放电控制器和逆变器来给蓄电池充电或者逆变,这种方案实际上就是给现有光伏发电系统外挂一个储能装置,可在目前任何一种光伏电站甚至风力发电站或其他发电站进行升级安装,形成站内储能系统,也可以根据电网需要建设成为完全独立运行的储能电站。

这种模式克服了直流侧储能系统无法进行多余电力统一调度的问题,它的系统充电还是放电完全由智能化控制系统控制或受电网调度控制,它不仅可以集中全站内的多余电力给储能系统快速有效的充电,甚至可以调度站外电网的廉价低谷多余电力,使得系统运行更加方便和有效。

图片

图2、配置在交流低压的侧储能系统


交流侧接入的储能系统的另一个模式是将储能系统接入电网端,如图3。显然,这两种储能系统的不同点只是接入点不同,前者是将储能部分接入了交流低压侧,与原光伏电站分享一个变压器,而后者则是将储能系统形成独立的储能电站模式,直接接入高压电网。

交流侧接入的方案不仅适用于电网储能,还被广泛应用于诸如岛屿等相对孤立的地区,形成相对独立的微型电网供电系统。交流侧接入的储能系统不仅可以在新建电站上实施,对于已经建成的电站也可以很容易的进行改造和附加建设,且电路结构清晰,发电场和储能电场可分地建设,相互的直接关联性少,因此也便于运行控制和维修。缺点是由于发电和储能相互独立,相互之间的协调和控制就需要外加一套专门的智能化的控制调度系统,因此造价相对较高。


3

配置在电源直流侧的储能系统

配置在负荷侧储能系统主要是指应急电源和可移动的电动设备,譬如可充电式的电动汽车,电动工具和移动电话等。

现阶段,交叉补贴的存在和居民建筑用能局限性还不能刺激居民用户侧储能的配套应用,但随着光储技术成本的降低,工商业用户侧光储应用价值将显现。


The role of energy storage system in photovoltaic power station  

 

 

 

1  

 

Ensure system stability  

 

In photovoltaic power station system, photovoltaic output power curve and load curve have great differences, and both have unpredictable fluctuation characteristics. Through energy storage and buffering of energy storage system, the system can still operate at a stable output level even in the case of rapid fluctuation of load.  

 

 

2  

 

The standby energy  

 

The energy storage system can play a backup and transition role when photovoltaic power generation cannot operate normally. For example, when the battery array cannot generate power at night or on rainy days, the energy storage system will play a backup and transition role. The amount of its energy storage capacity depends on the demand of the load.  

 

 

3  

 

Improve the quality and reliability of electricity  

 

The energy storage system can also prevent the voltage spike, voltage drop and other external disturbances on the load caused by the fluctuation of the grid to the system, the use of enough energy storage systems can ensure the quality and reliability of power output.  

 

 

No.2  

 

The main modes of energy storage systems  

 

 

 

1  

 

The energy storage system is configured on the DC side of the power supply  

 

The energy storage system configured on the DC side of the power supply can mainly be installed in the DC system such as photovoltaic power generation. In this design, the battery combination photovoltaic power generation array can be connected and regulated in the DC section of the inverter, as shown in Figure 1.   The photovoltaic power generation system and the battery energy storage system in the system share an inverter, but due to the large difference between the charging and discharging characteristics of the battery and the output characteristics of the photovoltaic power array, the maximum power tracking system (MPPT) in the photovoltaic grid-connected inverter in the original system is specially designed to match the photovoltaic output characteristics.  The output characteristic curve of the storage battery cannot be simultaneously satisfied.   Therefore, such systems need to transform or redesign the original system inverter, not only need to make the inverter can meet the requirements of photovoltaic array inverter, but also need to increase the battery charge and discharge controller, and battery energy management and other functions.  Generally speaking, the system is one-way output, that is to say, the battery in the system is completely dependent on photovoltaic power generation to charge, the power grid is not able to charge the battery.  

 

 

The picture  

 

Figure 1. Energy storage system configured at dc side of power supply  

 

 

 

Electricity from photovoltaic array in the system automatic dc inverter in front and battery balance, the main characteristic of this model is system of high efficiency and power output can be made of photovoltaic power station internal operation, can achieve a seamless connection, the output power quality is good, the output fluctuation is very small, etc., can greatly improve the photovoltaic output smooth, stability and control performance,   The disadvantage is that the inverter used needs special design and is not suitable for upgrading the existing photovoltaic power stations that have been installed.  Another disadvantage is that the batteries in the system can only receive power from the same unit to charge them, not the excess power from other nearby PHOTOVOLTAIC units or power stations.  In other words, it lacks the internal power distribution function of a large power station.  

 

 

 

 

2  

 

The energy storage system is configured on the AC side of the power supply  

 

 

 

Configuration is also called the power ac side of the energy storage system configuration in the ac side of the energy storage system, unit type ac side of the energy storage model shown in figure 2, it USES a separate charge and discharge controller and inverter to battery charging and inverter, this scheme is actually to the existing photovoltaic power generation system plugins an energy storage device,   It can be upgraded and installed in any kind of photovoltaic power station or even wind power station or other power station to form the in-station energy storage system, or it can be built into a completely independent energy storage power station according to the needs of the power grid.  

 

This model overcomes the dc energy storage system can't be extra electricity unified scheduling problem, the system charge or discharge completely controlled by the intelligent control system or controlled by the power grid scheduling, it not only can focus within the total surplus electricity to rapid and efficient energy storage system of charging, even cheap low excess power grid scheduling stand outside,   Make the system run more convenient and effective.  

The picture  

 

Figure 2. Side energy storage system configured at AC low voltage  

 

 

 

Another mode of the energy storage system connected to the AC side is to connect the energy storage system to the power grid, as shown in Figure 3.   Obviously, the difference between these two energy storage systems is only the access point. The former connects the energy storage part to the AC low-voltage side and shares a transformer with the original PHOTOVOLTAIC power station, while the latter forms an independent energy storage power station mode and directly connects the energy storage system to the high-voltage power grid.  

 

Ac side access scheme is not only suitable for power grid energy storage, but also widely used in relatively isolated areas such as islands, forming relatively independent micro-grid power supply system.   The ac side access energy storage system can not only be implemented in new power stations, but also can be easily transformed and additional construction for existing power stations. Moreover, the circuit structure is clear, and the power field and energy storage field can be constructed separately, with little direct correlation with each other, so it is also convenient for operation control and maintenance.   The disadvantage is that since power generation and energy storage are independent from each other, the coordination and control between them requires a special intelligent control and scheduling system, so the cost is relatively high.  

 

 

3  

 

The energy storage system is configured on the DC side of the power supply  

 

The load side energy storage system mainly refers to emergency power supply and mobile electric equipment, such as rechargeable electric vehicles, power tools and mobile phones.  

 

At present, the existence of cross-subsidy and the limitation of residential building energy consumption cannot stimulate the supporting application of residential user-side energy storage, but with the reduction of the cost of optical storage technology, the application value of industrial and commercial user-side optical storage will appear.  

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