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104-106 Controller option

Author: Source: Datetime: 2017-01-16 11:53:12

4.3.2.2 Controller option


In the independent operation of the photovoltaic power generation system, the controller is also a major component. PV controller to be based on system power, the system DC voltage, the battery square input number of people, the number of batteries, load conditions and the specific requirements of the user to determine the type of photovoltaic controller. In small-scale photovoltaic power generation system, the controller should be used to protect the storage battery, the general small-power photovoltaic power generation system using single pulse width modulation controller; in large and medium-sized systems, the controller must have more protection and monitoring Function, so that the battery charge and discharge controller into a system controller, therefore, high-power photovoltaic power generation system using multi-input controller or with communication and remote monitoring and control functions of the intelligent controller. With the controller in the control principle and the progress of the use of components, the current system controller has been used in advanced microprocessor, software programming and intelligent control.
When selecting the controller to pay special attention to its rated operating current must also be greater than the solar cell components or the square of the short-circuit current and load the maximum operating current. In order to adapt to future system expansion and ensure long-term stability of the system, the proposed selection of the best choice for a high model. For example, the design of 12V / 5A controller can be used to meet the system, the actual application may consider the choice of 12V / 8A controller. Also note that the selection of the controller function is not the more the better, pay attention to select the applicable and useful in this system function, abandon the extra features, otherwise not only increase costs, but also increase the possibility of failure.
Controller, because of the control circuit, control different, from the design and use of terms, according to the square of the photovoltaic cell input power and load power of different, optional low-power, medium power, high-power type, or Dedicated controller. The main technical parameters of the controller are as follows.
(1) System operating voltage
System operating voltage, that is, rated voltage, refers to the photovoltaic power generation system in the battery or battery voltage. The voltage should be based on the DC load voltage or AC inverter configuration to determine the configuration, generally 12V, 24V, the high-power controller also has 48V, 110V, 200V and so on.
(2) Rated input current
The rated input current of the controller depends on the output current of the solar cell module or the square matrix, and the rated input current of the controller should be equal to or greater than the output current of the solar cell module or the square matrix.
(3) The maximum charge current
The maximum charge current is the maximum current of the solar module or square output. According to the power size is divided into 5A, 6A, 8A, 10A, 12A, 15A, 20A, 30A, 40A, 50A, 70A, 100A, 150A, 200A, 250A, 300A and other specifications. Some manufacturers use the maximum power of solar modules to represent this content, indirectly reflects the maximum charge current of the technical parameters.
(4) The rated load current of the controller
That is, the controller output to the DC load or inverter DC output current, the data to meet the load or inverter input requirements.
(5) The number of square solar cell input
The number of input channels of the controller should be more than or equal to the number of solar cell array design input: low-power photovoltaic controller is generally only - way solar cell array single input; high-power controller is usually multi-channel input , Each input maximum current = rated input current / number of input channels, therefore, the output of each battery square should be less than or equal to the controller each channel to allow the maximum input current value. General high-power photovoltaic controller can input 6, up to 12-way, 18 Road.
(6) Circuit itself loss
Controller circuit itself loss is also one of its main technical parameters, also known as no-load loss (quiescent current) or maximum self-consumption current. In order to reduce the loss of the controller and improve the conversion efficiency of the photovoltaic power supply, the loss of the controller circuit itself should be as low as possible. The maximum self-loss of the controller shall not exceed 1% of its rated charging current or 0.4 W6 according to the circuit itself, the loss is generally 5 ~ 20mA.
(7) Battery overcharge protection voltage (HVD)
Battery overcharge protection voltage is also known as full of open or overvoltage shutdown voltage, generally according to the needs and different types of batteries, set in the 14.1 ~ 14.5V (12V system), 28.2 ~ 29V (24V system) and 56.4 ~ 58V (48V system), the typical values were 14. 4V, 28.8V and 57.6V. (HVR) of the battery charge protection is typically 13.2 to 13.4 V (12 V system), 26.2 to 26.8 V (24 V system) and 52.4 to 53.6 V (48 V system), respectively, and the typical values are 13.2 V, 26.4V and 52.8V.
(8) The battery over-discharge protection voltage (LVD)
Battery over-discharge protection voltage, also known as undervoltage or undervoltage turn-off voltage, generally according to the needs and different types of batteries, set at 10.8 ~ 11.4V (12V system), 21.6 ~ 22.8V (24V system) And 43.2 to 45.6 V (48 V system), typical values are 11.1 V, 22.2 V and 44.4 V, respectively. (LVR) of the battery over-discharge protection is typically set between 12.1 to 12.6V (12V system), 24.2 to 25.2V (24V system) and 48.4 to 50.4V (48V system), respectively, 12.4V, 24.8V and 49.6V.
(9) Battery charging float voltage
The battery charge float voltage is generally 13.7V (12V system), 27.4V (24V system) and 54.8V (48V system).
(10) Temperature compensation
The controller generally has a temperature compensation function to adapt to different environmental operating temperature, set a more reasonable battery charging voltage. Controller temperature compensation factor should meet the technical requirements of the battery, the temperature compensation value is generally -20 ~ -40mV / ° C
(11) Working environment temperature
The use of the controller or operating temperature range with the manufacturers generally in the -20 ~ +50 ° C between.
(12) Other protection functions
① controller input and output short-circuit protection function Controller input and output circuits should have a short circuit protection circuit to provide protection.
② anti-backfill protection controller to prevent the battery reverse to the solar battery charging protection.
③ reverse polarity protection function Solar battery module or battery access controller, when the polarity is reversed, the controller should have the function of protection circuit.
④ lightning protection function Controller input should have a lightning protection, lightning arrester type and rating should be able to ensure absorption of the expected impact energy.
⑤ resistance to impact voltage and impulse current protection in the controller of the solar battery input 1.25 times the nominal voltage applied to lh, the controller should not be damaged. The controller charging circuit current to 1.25 times the nominal current and continued lh, the controller should not be damaged.
In addition to the above main technical data to meet the design requirements, the use of ambient temperature, altitude, protection and exterior dimensions and other parameters, and manufacturers and brands are also the controller configuration selection factors to consider.
On the inverter and controller of the specific model matching, can be directly from the manufacturers to find the product information, in-depth understanding of the system and other hardware matching, see the relevant sections.
To make good use of solar photovoltaic power generation of such intermittent energy has three technical ways: First, set the energy storage device; the second is to take more complementary; third is connected to the power grid. For remote and islands and other areas, often the power grid is too late, can only build an independent power generation system, and with energy storage, often using more complementary hybrid power generation system. In fact, this is to use photovoltaic power generation to solve the problem of power supply without electricity, not a simple photovoltaic power generation system, and to build a separate type of light - wood - microgrid. Simply use photovoltaic power generation to ensure the normal power supply throughout the year often poor technical economy. China in the 20th century, built in the 1990s without electricity County, non-rural PV power plant is such a situation. Figure 4-48 is a block diagram of a 25kWp PV system built in Shuanghu, Tibet, China
Here, the function of the diesel generator set is as a back-up power supply to ensure reliable supply of PV power system. In accordance with the overall program design, provisions in the following two cases, you can start the diesel generator.
① In the energy storage battery loss of electricity, can not meet the electricity load needs, timely start diesel generators, rectifier charging equipment to charge the battery pack to ensure the normal operation of the power supply system.
② When the PV power system can not be powered by the inverter failure or other reasons, the diesel generating set is started and the power supply is directly supplied to the user through the AC distribution system.
The power setting of the diesel generator is determined by the load power and the power supply guarantee rate of the PV power generation. If you use the LOLP method in Section 3.2, you can set a value of LOLP, such as 0.1, which means that the load loss rate of 10%, which is 90% of the load power supply guaranteed by the photovoltaic power generation, 10% from diesel power generation Guarantee. So the capacity of photovoltaic power generation system design can reduce the capacity of 10%. To do so, in general, technical and economic indicators are appropriate.
Rectifier charging device is the role of the diesel generator sets issued by the AC into DC, to charge storage battery pack. The main design requirements for the rectifier charging equipment of Shuanghu PV power station are as follows.
Capacity: 75kW
Input: three-phase AC 380V
Output: DC 300 ~ 500V
Maximum output current: 150A
Protection functions: input phase loss alarm, output over-current, short-circuit protection, voltage warning open or current limiting

Rectifier charging equipment selection KGCA series three-phase bridge thyristor voltage regulator rectifier circuit. By the KC-04 integrated trigger circuit, PI control circuit control, detection and pulse amplifier and other components. All the components are installed in the same cabinet. The instrument, indicator and control buttons are mounted on the panel. Working state with "steady flow", "regulator" and "manual" three, can be constant current or constant voltage charging, the external dimensions of 900mmX562mmX2200mm.
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