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107-108 Verification of the design of independent photovoltaic power generation system

Author: Source: Datetime: 2017-01-18 13:27:32

4.3.3 Verification of the design of independent photovoltaic power generation system

Independent photovoltaic power generation system in the completion of design, equipment procurement, installation and put into trial operation to verify the design. This is responsible for the quality of built photovoltaic systems, and is directly related to the interests of users.
Design verification should be carried out in accordance with the relevant standards. In October 2004, IEC issued IEC62124 independent photovoltaic system design verification standards. This standard specifies the procedures for conducting independent PV system design tests, as well as the technical requirements for system design verification, so that the overall system performance can be evaluated. At present the domestic standard only GB / T 19064-2003 "domestic solar photovoltaic power system technical conditions and test methods", the relevant national standards may be being developed.

IEC 62124 includes technical performance testing methods and procedures applicable to independent photovoltaic power generation system. Independent photovoltaic system consists of multiple components, even if the parts meet the technical and safety standards, the technical specifications of the entire system to meet the design requirements, still need further verification. The standard verifies the design and performance of the system and evaluates the system performance. Here only to verify the necessary system test equipment and equipment, as well as performance testing and other aspects to be described. Apparatus and equipment used for system testing
Conducting a system test The following instruments and equipment are necessary.
• DC voltage and DC current measuring instruments
• DC ammeter or some other monitoring means;
• a time-table or some other monitoring means;
• PV standard devices selected and calibrated as per GB / T 6495. 2-1 to cooperate with array component tests for spectral response;
•Temperature Sensor;
• Check that the standard device is in the same plane as the array (within 5 °);
• An automated data acquisition system that facilitates system monitoring;
• Environmental monitoring instruments.
On the data acquisition system technical description.
The data logger should use at least 12-bit A / D conversion and input range should be greater than the estimated maximum positive and negative voltage. The data acquisition system must be reliable. Tests will be restarted if more than 4 hours of data are lost in the test, or if important data is lost due to power loss.
The sample rate of the data logger is determined by the type of charge controller. For a switch controller, the sample rate of the data logger is at least two times faster than the charge controller's switching time. For example, if the regulated voltage circuit operates every 10s, the sampling rate is 5s or faster.
The charge controller uses a constant voltage or pulse-width modulation circuit, and the switching time may be milliseconds instead of seconds. The sampling frequency of the data acquisition recorder is at least twice the switching frequency of the charge controller. If the data logger sampling rate is not fast enough, then one way is to data acquisition system input plus an integral / filter circuit, sampling once per second. The time constant of the integrating / filtering circuit should be at least twice the sampling period.
The oscilloscope can determine the type of controller and the switching frequency.
Each test should be an average of 5min storage time data. 

The parameters in Table 4-15 will be tested and determined separately.

Table 4-15 Test Paraeters

Test parameters Record the value Notes
Array voltage Minimum, average and maximum The array voltage is measured on the battery before blocking the diode
Load voltage Minimum, average and maximum
Battery voltage Minimum, average and maximum
Array current Minimum, average and maximum  
Negative load current Minimum, average and maximum
Battery current Battery capacity flowing in and out (A * h)
Air temperature average Open-circuit voltage method to determine the equivalent of photovoltaic modules GB / T 6495. 5-1996 as a standard, in the temperature compensation sensor or battery negative measurement
Component temperature average
Battery temperature average
Solar irradiance Amount of solar radiation Standard equipment, short-circuit current and the temperature of the equipment
Load operation Load running time

The technical requirements of the sensor are as follows.
The range of voltage sensors should exceed the maximum expected voltage with a resolution of at least 0.01V or better. The range of the current sensor should exceed the expected maximum positive and negative current and the resolution should be at least 0.01 A or better.
In addition to the accuracy of ± 1% FS within the outside, the DC voltage and current measuring instruments should be in accordance with GB / T 6495.1-1996 "PV current - voltage measurement."
The range of the temperature sensor should exceed the expected maximum positive and negative system temperature and ambient temperature with a resolution of at least 1K or better. The accuracy of the temperature sensor should be 2K or better.

The total radiation table should have a suitable range. The accuracy of the total radiation table is at least 5% of the reading taxi. 

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