“Data-based” sunshine

Polaris solar PV net news: beginning in 2014, China PV electricity price subsidy is no longer unified electricity price, but according to the advantages and disadvantages of solar energy resource three types of areas, these three areas will receive 1, 0.95, new benchmark 0.9 Yuan per kilowatt hour price (table I). Solar resource data for the power plant site selection, power generation is expected to have a direct relationship, but accumulation of PV industry in this respect is also very limited.

Table: a new benchmark of each resource area price (Note: the Tibet Autonomous Region, the benchmark price shall be separately formulated; price unit: Yuan/kWh)

Sources of data

End of 2013 interim measures for the administration of national energy Board issued a photovoltaic power station, one of which the 12th article project development, there must be measured, or representative of measured data. In a document submitted to the National Energy Board, China 96 base station 10 mean level of radiation in the statistical tables to be submitted as an attachment. Data table of this throughout all of China’s provinces, municipalities, including longitude, latitude, altitude, the water level is given years of exposure, tilted surface annual radiation dose and equivalent full hours, and many other parameters. Files outside of this classification level is very difficult to see, in the new project, to get useful resource data, or bought from the local Meteorological Bureau, free from NASA to find either.

At present already there have been doing research on solar radiation. United States NASA (NASA) through the inversion of satellite data, free of charge for users with a resolution of 3-110 solar radiation data. NASA’s database has become China’s main source of getting solar resource data of the photovoltaic industry.

The International Electrotechnical Commission (IEC) on behalf of Lin Yang of China experts believe NASA’s free access to information is not accurate, “somewhere in Gansu province, we compared data from NASA open data values are given by a 1600kW · h/m2 · a, but the actual figure is close to 2000kW · h/m2 ·. NASA have large errors on access to information, especially in cloudy, rainy weather is more errors at 25%. ”

LDK engineering company Deputy General Manager Zhang Lei also said that “NASA is famous for its data, but it is not a reliable source. ”

United States renewable energy laboratory (NREL) in the light of research on solar power-related resource data, they use NASA data, but its resolution is 3-40 km of resource data, in its launch of SYSTEMADVISORMODEL (SAM.NREL.gov) free design software, gives more accurate resource data.

Photo: NREL SAM page

“In the context of China, SAM will be provided free of charge to users within five kilometers of its IP location data, I can’t download over this range of data, but data can send mail request to NREL project is located. “Lin Yang had received NREL response message and get the data you want,” this program focuses on United States PV market demand. “Lin Yang, light resource data source is more than,” I did try MeteoTest Switzerland Meteonorm software developed by companies, does anyone still use France meidi MeteoDynSolar tool company data. Some domestic professional teams in recent years, will offer a series of free national resource data source. ”

China’s vast area, light and solar radiation resources across the country are very different, according to the national weather service wind energy solar energy assessment Center standard, China’s solar energy resource areas are divided into four categories (see table II).

Figure II: 1978-2007 national average total direct radiation (source: the national weather service)

Figure three: United States professional resource assessment 3Tier’s data, based on satellite meteorological data and model projections, accurate resolution to 3km

After decades of accumulation, China also has its own light resource data. Beginning in 1953, China measured solar radiation, there are 2,300 stations and 310 meteorological station. 122 of which has over 10 years of data in the baseline Observatory meteorological station only 96. CMA is the owner of these data.

National Weather Service wind energy solar energy resources Center (hereinafter referred to as the wind was too), Zhao Dong, a researcher, said China Meteorological Administration has two sets of related data, 96 base stations across the country is the core data. One set of data from weather satellites, through the official model, taking into account the calculated from a set of parameters such as longitude, latitude, altitude, real data is then compared 96 base station check out; another set of data from meteorological sites over more than 2000 hours of sunshine in the country with 96 weather data such as data aggregated results. Wind Center current power station solar resource assessment for the PV industry and solar power specializes in numerical weather prediction services.

Shenhua subsidiary guohua energy investment company is the China Meteorological Administration Center for wind and solar resource assessment of long-term clients, Zhang hua (anonymous) told reporters that “we are doing site resource data when used to light, one coordinate point to about 150,000. ”

Data charges from the met Office, Zhang Lei also expressed dissatisfaction, “hope power plant investors data free of charge to the national weather service. We invest will generate tax revenues, which propped up the Government’s operations. Now the met Office data to sell these, to the detriment of the PV industry as a whole is. ”

In an interview that most of the developers of power plants, early buying data from the met Office at the beginning of the project there are not many, some developers would pass the relationship gets research from existing data, is more similar to NASA’s free data. Zhang Lei has passed to China’s meteorological resources sharing network, a Web site for a free atmosphere data, “but then the met Office shut down this website. “In fact, even if the purchase data from the met Office, which could not be entirely accurate. Zhang said, on the one hand the annual resources will be different because of weather changes, on the other hand, “don’t know why, Eastern region of meteorological data is always on the low side. ”

Reporters found in many areas in the West, different station in the same region the Assembly inclination maximum not more than 5 degree. Zhao Dong explained, “reliable resource data is necessary. Most directly affected are dip in power plant design calculations, there are calculation method of main issues, differences from the resource data. “Currently China has 98 a Observatory station monitoring total radiation volume data, 17 a Taiwan station has directly radiation data, and PV dip calculation more rely on direct radiation data,” even also total radiation volume level of light resources area, some place direct radiation component more, some place scattering radiation component more, which area component more tendencies Yu flat put, and former component track Sun more suitable. “Zhao Dong added that” the optimum tilt angle calculation in addition to radiation, also taking into account factors such as temperature and wind speed on the ground. ”

Station meteorological instrument

Currently most of the PV power plant to install a meteorological instrument, but most equipment data collection is incomplete. MEMC to invest in China’s first hydropower station–di-sheng are being collected in Dunhuang angle radiation, its project manager Qiao Lijun said that “angle radiation level data than the data can better respond to power plant generating capacity and operating conditions. “In Zhang Lei seems, complete of meteorological instrument at least to has four block sun radiation table, respectively measurement total radiation value, and scattering radiation value, and dip radiation value and direct light data, which direct radiation of high precision track device to occupy high of cost, some station to save this aspects of budget, direct radiation volume on directly with total radiation volume minus scattering radiation volume, this practices does not perfect.

“Photometric data to optical power forecasting services, optical power forecasting needs to do to test the four watch values as the basis. “China PV expert Wang Sicheng visits West power station found that angle radiometer not installed on some power plants, but the power plant operation and maintenance personnel go through software through to the level of emission data, and computing needs.

China Guangdong nuclear power station on the site of Dunhuang concession set up solar radiation monitors last year recorded data, but failed because of the problems and did not get all the data for the full year. But according to numbers 8 months (see table III), the measured exposure data with the NASA data and feasibility studies reference error exceeds 30%.

Table III: cgnpc Dunhuang concession projects measured daylight data comparison with NASA and research data

Success that this error is normal, “the weather conditions are not the same every year, so we need many years of accumulated data. “And the quality of meteorological instruments is one of the reasons is the variance of the data. In Dunhuang, China Guangdong Nuclear concessions project operation and maintenance records, meteorological instrument (model WAMS620-SP) frequent questions, such as meteorological data instability, few data transmission the background and meteorological data are not allowed, and so on.

According to Zhao Dong experience, weather instrument quality is one thing, even if good weather instrument, each of which block the radiation table also need to calibrate the local meteorological station. Without calibration, each table has different error. Wang Sicheng said radiation data and measurements should be consistent with the GB/T20513-2206 standard file photovoltaic system performance monitoring, measurement, data exchange and analyze the contents of the Guide, the technical standards are equivalent to IEC61724.

Current meteorological instruments in accordance with their different functions, prices ranging from tens of thousands of up to a hundred thousand of. Lin Yang believed that “foreign irradiance tables more precise meteorological instrument, photosensitive component technology is one of the main reasons would be better. See Japan EKO test equipment, its high-end radiometer equipped with special cooling fans can avoid radiation table internal component temperature drift problems. “A success, none of the differences of domestic products and imported products to assess directly the” we irradiated by meteorologists using the domestic table, the quality is no problem, the key is to look at the calibration. ”

Compared with most businesses invested insufficient resources and facilities, State-run days in Dunhuang have built China’s first third-party field experimental station, in which a complete meteorological observation equipment and optical resources cost more than 2 million. The system has accumulated a one-year data, State-run day is to sort and analyze the data.

Figure four: State-run energy is located in Dunhuang’s meteorological equipment

Chicken power forecasting

In order to better manage the PV electricity and scheduling, national grid asked the utility to install light power prediction system. Zhao Dong believed that “light power forecasting system must be combined with radiation observation data can play a role, in particular Ultrashort time prediction. “In his view, optical power forecast is the nature of solar radiation data in conjunction with other meteorological observation data to power,” despite the lack of valid data resources, the system-it is difficult to play a role. ”

Liu Hailin Jin Tagan power station stationmaster, “says power prediction system is installed on, but to no avail. “The fact is that PV-TechPRO reporter visited most of the light in the power station power forecasting systems are not in use. Jinta, Gansu province Liu Shengping, head of new energy power station in Asia, “said new energy grid in fine wine region in Gansu province sent out the ability to elevate coordination meeting requires PV plants installed active power control system, the system interfaces with the province, if there is a super maximum output limit opportunities, adjusting feedback information. “Liu Shengping learned this system at 590,000, they have yet to install the system, will look at how enterprise is installed, and whether they could play a role in power generation to make arrangements.

Zhang Lei’s views on ground station optical power prediction system is that “real power forecast a series of test equipment is to be installed in the station, including humidity, cloud cover, precipitation sensor, the only way to achieve power prediction, instead of the current power projections. Just like the F1 Formula One racing game provides real time weather information services, such as will there be rain, there will be rain in a few minutes. “In his view, needs a process of accumulation of data collection, the only way to make forecasts more accurate.

As the representative of IEC standards in China, Wang Sicheng presents IEC61725 (solar power predictive analysis) amendments to this standard there are three theoretical analysis model (peak distribution of cosine, the flat distribution).

Lin Yang, said, “If you don’t power prediction refinement every day, then there is no better way to ensure accuracy. “Laiweisaier and Tian Yuan Ke Chuang offer to integrate their various radiation meter and meteorological data acquisition equipment package, which has famous Kipp&Zonen in radiation monitoring equipment. Laiweisaier has developed a DXPresee power prediction system, offers 15-minute resolution super short, short-and medium-power forecast. United States Sandia National laboratories are working on cloud impacts on power generation efficiency, they are placed in a large power plant and a distributed power plant has more than one solar radiation sensor, with contrast variation of irradiance and output power of the power difference. Their analysis to quantify each plant’s power for a short time, and create a model to simulate the change. Sandia Labs team plans to expand the experiment to more power plants to verify their models, the impact of fluctuations on the grid and photovoltaic power.

Success for optical power forecast offered new solutions, “power plant owners can use digital weather forecasting, real-time meteorological data to power forecasting services unit. “China meteorology solar power professional numerical weather forecast mode system using Council to analysis forecast system LAPS three dimensional cloud analysis technology, and in the scale meteorological mode WRF and atmospheric radiation transmission mode SES2, through based on satellite remote sensing vapor, and visible and infrared channel data and cloud classification, and cloud detection, numerical products of LAPS three dimensional cloud analysis improved technology, improved has cloud physical parameter of simulation and forecast and sun radiation of simulation and forecast. The system for making three dimensional cloud field weather conditions and solar radiation provide relatively accurate numerical methods for the simulation and prediction, in order to provide accurate and reliable simulation of solar radiation generating capacity forecast and prediction based data.

Zhao dongwan said digital meteorological data service for the next three days, according to the forecast of the price of points, as well as elements of data several times a day, but different, “but generally costs less than 100,000 per year. “In support of digital weather forecast, PV can be achieved within 4 hours of ultra short-term prediction and forecast of short-term power within 72 hours. Dong Runhuan optical power statistics for prediction of meteorological information including wind speed curves, wind rose, wind Profiler, radiation intensity, and cloud cover curves and temperature curves. After the forecast, this device to the statistical power of the predicted value and the actual value and the mean absolute error and root mean square error, and the percentage of error is less than 20%.

Ground power station due to large scale meteorological instrument can be built and distributed projects is difficult to achieve for small and medium, for distributed power prediction will be difficult to achieve. Success also to think of the problem, “according to my ideas, local power company, or make predictions about electric power dispatch agency can unify, is technically feasible at present. Meteorological departments can contribute to the unification of a region do forecasts. We’ve done a centralized forecasting system, which can make predictions about as many points. “Due to the current distributed does not scale, success system is not applied.

When talking about weather service charges, Zhao dongwan said, “our charges is to support the wind Center more research and development operation. “In 2014, the success will warming effect of solar radiation on the component and output attenuation attenuation relationship, haze and efficiency of photovoltaic systems, dust reduction factors such as study subject, to better help for fine design of PV systems.

Original title: data-based sunshine

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