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Estimating the Power generation of home PV stations has always been a matter of concern to all. Accurate estimation has different meanings for different roles in the industry. For power plant developers, estimating power plant capacity directly affects the site selection, key components selection and other prophase work. For the power plant operators, estimating the power generation can help to evaluate the plant, i.e. power generation status assessment, loss evaluation and original performance evaluation. For investment, the direct impact on the investment income of the power plant, today affects the corresponding financing plan, power station transaction decision-making and investment decision-making. For sales and distribution personnel, it is also hoped that the PV plant will generate power for a certain period of time, to facilitate its trade in the power plant, as well as the regional distribution of power grids. According to the Rabbit experience, the power plant assessment, said easy also easy, said difficult is also more difficult. It is easy to point out that the key calculation methods and the factors that need to be considered are basically clear. In certain more mature areas, some service providers can achieve high-precision power generation assessment. It is difficult to say that the key model required by the variables are unknown, if it can be based on the corresponding empirical research, accurate understanding of the relevant parameters, then the most difficult to assess the power plant bottleneck is solved. Today the rabbit hands to provide you with a photovoltaic power generation calculation method, of course, is not the only way. Hope can help everyone's usual business.
工欲善其事 its prerequisite, the power generation assessment of PV plants needs to take into account the relevant data input, model establishment and correction factors. Although many simulations are performed using software, it is helpful to understand the general idea of how to calculate the power generation of PV plants. More helpful in handling special situations. At the same time, different soft has its own limitations. Later portions of the data also need to be revised separately. Therefore, the understanding of the relevant principles is very necessary. First of all, in this issue of the rabbit in place we summarize the basic ideas of simulation and apply to the principle.
Considerations for calculating power generation
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Environment variables: Photovoltaic power plants mainly rely on light resources to eat, the most important is the light irradiance, ambient temperature and other weather variables. A) The light irradiance directly affects the energy raw material obtained from the power station. Simple analogy, as the coal resources of the fire power station, water resources of hydropower station. Photovoltaic power Plant's light resources directly affect the power station how much raw materials can be converted to power generation. On the acquisition of light irradiation resources, in the previous period, the rabbit has talked about, we can refer to the relevant content in-depth study. The computational accuracy of light irradiation is affected by the method of illumination calculation. In general, when estimating light irradiation, the use of water level irradiation, which involves the level of the radiation to the tilt surface of the factors. Generally used in Pvsyst is a preze or hay two model. b) The environmental temperature mainly affects the conversion efficiency of the power plant's own devices. components, the operation of the inverter is directly affected by the temperature. The relationship between power efficiency and temperature is mentioned in the article before the rabbit. In the actual operation of the power plant, it can be found that the high temperature weather, the power generation will have a noticeable attenuation. Of course, the operating efficiency of the inverter is also affected by the temperature. As for the operation of the inverter, the rabbit will be described in detail in a later article. c) Other weather variables include: dust, snow, and extreme weather. The variables are mainly the previous two variables. Each year related to the various regions, photovoltaic power plants will have associated losses.
Key electrical Models
The main electrical appliances are photovoltaic modules, inverters and box-type transformers. The operation efficiency of the three is directly related to the operation State of photovoltaic power plant. A) PV modules: The main considerations are: temperature, lighting and efficiency.
I. For temperature, the power generation of the components will decrease. This will indicate the relevant temperature coefficient when the PV cell comes out. According to this coefficient, the power of the component can be corrected. II. The illumination angle and calculation method will produce certain loss. First, the measurement of the component is done in the case of the light source being in the component. However, normal solar illumination is changed during the day, and the angle difference caused by light incident to the component will cause a certain loss. This requires a correction of the power of the component in the estimation. III. Low light response. The output power of the components differs from the actual power under different light intensities. Thus there is a certain coefficient of correction.
b) PV inverter:
I. Inverter efficiency: The inverter itself has its own operating efficiency, and is affected by its working conditions and the surrounding environment. The general inverter has an associated operating model that can simulate its power output. II. Inverter operating power and voltage window. The inverter has a specified input voltage and power range. For voltage, when a certain voltage range is exceeded, the inverter will not be able to complete the maximum point tracking of the string running power, or the inverter will shut down. For power, when power exceeds a certain range, the inverter will limit the power output or shutdown. This kind of operation will directly affect the operation efficiency of the power station.
c) Box-type Transformers: Mainly related to the nominal capacity of the box change, with load loss and no load loss
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A variety of factors will affect the actual power generation of a) dust. Ash accumulation is a major factor affecting the power generation of photovoltaic plants. Mainly affects the power generation capacity of the Volt component. In dry desert areas, plant concentration areas and construction-intensive areas are particularly severe. According to experience, the PV module will generate more than 10% of the power generated before the cleanup. In different regions, the average ash loss of different months, seasons or years can be summed up according to experience. It is very meaningful to accurately estimate power generation.
b) Snow. The effect of snow on light irradiation in some areas will affect the power output of PV modules in specific seasons.
c) Loss of mismatch. Mismatch losses are mainly generated in the process of parallel and tandem lines. On the one hand, due to the component power and power generation parameters vary, on the other hand, it depends on the actual installation process of the component inclination is not good, the region temperature difference, shade and so on. The mutual restriction between components can lead to some loss. Of course, the mismatch of power generation between the different areas connected by the inverter will also be associated with mismatches.
d) Shade. There are many cases of shadow occlusion. The first and foremost occlusion between arrays is difficult to avoid. Need to be minimized by design. In addition to surrounding buildings, seasonal weed growth can lead to a loss of the component's shade. A good estimate of this loss can help to accurately assess the power generation of the plant.
e) line loss. The power transmission process will inevitably cause line loss. Line internal resistance, the contact resistance of each node, leakage and so on. The main losses can be calculated according to the relevant parameters.
f) Limiting factors. In the power grid operation, in the power dissipation or power stable operation of the consideration, the photovoltaic power plant will be rationing, which is also the main problems encountered in the West power station. g) Loss of field operation. Inverter and other electrical appliances in fact in the standby time will consume energy, while the field part of the electrical appliances are also in the photovoltaic array directly to the power, so that there will be part of the loss.
Evaluation of power plant modeling data correction based on computational logic illumination resources
Light Resource Assessment
The light irradiance actually falling on the component plane is calculated according to the database statistics. This involves the following two steps: a) actual level of illumination data collection. This is described in detail in previous articles in rabbits, how to choose different data sources and how accurate they are. In the Rabbit article also describes how to obtain the light irradiation data processing. b) The algorithm of the horizontal surface light irradiation data to the component plane light irradiation. There are many models that have been built up. Rabbits will be in the back of the article with the small friends in-depth discussion. 12 Plant Modeling
According to the existing PV module operation data, the PV inverter operating data and the box-type transformer are modeled on the power plant. The main use of photovoltaic power plant simulation software simulation, the relevant parameters input.
This includes confirmation of the following parameters:
A) PV module related parameters B) environmental parameter confirmation C) PV inverter related parameters d) box variable correlation parameter e) PV power Station design connection method F) PV power station operation mode
With the above model and input data, the approximate light irradiation output of the plant can be estimated, but the relevant data correction is still needed, mainly according to the results of the losses mentioned in this paper.
Some of these data have already been reflected in the relevant software, and some of them need to be revised manually.
A) Ash Snow (b) Shade C) mismatch D) line loss e) Voltage limit f) field loss g) Low light response h) Component temperature response I) power and voltage response of inverters Summary
The above is for the entire power generation assessment involved in the principle, need to consider the factors and specific simulation steps introduced, PV plant simulation needs to consider more factors, mainly summarized in this article.
The specific power generation simulation mainly involves the following steps:
Determination of light irradiation resource data: through the relevant database, service providers and other channels to obtain data resources.
Build the model. The photovoltaic power plant model is established by relevant software to estimate the conversion rate of light resources.
Fix the data. The data is corrected by the actual situation of the known PV plant.
Estimating the amount of domestic photovoltaic power generation can be followed, as long as you maintain your home solar power system, the use of high-quality power station components, your power station will generate electricity, your income will rise.
Teach you how to estimate the amount of household PV power
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