Photovoltaic development scale.
National installed PV power generation reached 130GW, 100GW for PV power plants and 30GW for distributed PV;
In 2017, 53GW of newly installed PV power generation, of which 33.6GW of PV power plants, an increase of 11% year-on-year; 19.5GW of distributed PV, an increase of 3.7 times year-on-year.
January-April 2018 New distributed PV installation 9GW, an increase of 180% year-on-year, accounting for 80% of new installations ;
Showing the trend of centralized PV plants slowing down and distributed PV power generation speeding up.
Reflecting the government's guidance on PV market segments.
Tilt from PV resource-rich areas to less-rich areas
Tilt from western to eastern regions
Tilt from centralized to distributed
Development of household PV.
2017 is the "first year" of the development of household distributed PV. The rapid development of household PV, 500,000 household PV installation, new installed capacity of more than 3GW.
Not subject to quota restrictions, grid-connected mode can be freely chosen, limited subsidies court household PV still has great potential for development. The number of household PV installations is expected to approach 10GW in 2018.
02 energy storage in distributed photovoltaic power generation
Distributed photovoltaic characteristics.
Output characteristics: ① periodic ② random ③ volatility
Access characteristics: ①Diverse types ②Dispersed multi-point arrangement ③Independent control ④Low access voltage level ⑤Existence of single-phase operation
Problems of high proportion distributed PV: ① Power quality
①Power quality
Multi-machine parallel coupling of inverters and frequent throwing amplify power quality problems.
Harmonics: mainly current harmonics, which can generally be identified only through test analysis;
Voltage three-phase imbalance: single-phase operation exists in distributed PV.
It also depends on the short-circuit capacity of the parallel network and the total number of distributed PVs connected to the grid under the same medium voltage boosting transformer
Serious power quality problems can cause damage and interference to nearby power generation systems, sensitive power-using equipment, and signal transmission.
②Power factor and reactive power configuration
Distributed PV access will reduce the system power factor;
The power factor of PV units connected to the distribution network should be adjustable within the range of grid requirements, and a certain amount of reactive power should be configured according to the standard requirements;
It would be a huge investment to deploy reactive power for short term use but of a large order of magnitude;
If the PV itself is to be compensated for reactive power, its active output will be affected and the economy will be affected.
③To the distribution network local voltage stability
Change the voltage distribution: In single radiation distribution network, the voltage theoretically decreases gradually along the transmission line tidal direction, PV access has a lifting effect on the voltage of the parallel network;
Change voltage deviation: The change of voltage distribution causes the change of voltage deviation, positive deviation or negative deviation, increase or decrease, when access to a certain scale, there may be a voltage crossing limit;
Causes voltage fluctuation: The change of power generation directly leads to voltage fluctuation at the access point. When the distributed power output is positively correlated with the load, the voltage fluctuation decreases, and vice versa, the voltage fluctuation increases.
Problems solved by energy storage in distributed photovoltaic power generation.
To reduce the impact of distributed PV power generation on the distribution grid and ease the pressure on the grid, the German government has been implementing financial subsidies for the installation of energy storage systems for distributed PV power generation below 30kW since 2013.
Energy storage technology can provide backup power, frequency regulation and other grid services. Combining the two can provide further advantages, in particular by enabling continuous power supply at night, increasing output during available generation hours and improving grid flexibility. In distributed community and rooftop systems, the combination of solar and storage technologies can also reduce distribution grid stress and defer or reduce infrastructure investments. At the macro level, energy storage and solar power can increase the penetration of solar facilities without major changes, thereby reducing carbon emissions. The combination of energy storage technology and solar power can also serve as a fast track to electrification in emerging markets.
Energy storage to improve the consumption of distributed PV.
Centralized energy storage: ① line tide control ② grid-connected reactive power compensation ③ node voltage regulation
Distributed energy storage: ① centralized control of light and storage integration ② active power stabilization at access points ③ reactive power balancing at access points ④ voltage stabilization at access points
In the regional distribution network with high penetration distributed PV access, distributed energy storage and centralized energy storage can be configured separately or simultaneously to solve different problems.
Distributed generation and microgrid technology will develop in the direction of plug-and-play, multi-energy complementation, deep integration of energy storage, gradient utilization, active grid support and two-way interaction.
Energy storage system is the key core equipment indispensable to support microgrid operation.
Role: maintain the power balance inside the microgrid; support the voltage/frequency stability of the microgrid
03 Development opportunities of distributed PV + energy storage
Foreign policies on energy storage.
Germany's grid-connected subsidies have also been significantly reduced since 2009. In the case of residential rooftop projects with an installed capacity of 30kW, for example, the price of grid-connected subsidies has been reduced from a historical high of 0.57 EUR/kWh in 2004 to 0.12 EUR/kWh in 2014. This has left residents facing a continuously increasing electricity purchase tariff on the one hand, and a continuously low grid-connected subsidy for self-generation on the other. Germany, where grid-connected tariff subsidies are gradually fading out, has started to shift its subsidy policy to subsidize battery energy storage systems.
Increase the "own consumption incentive" to encourage those with less than 500kW of rooftop photovoltaic power system self-generation. Thus, Germany has further promoted a fair energy market on the one hand, and reduced the pressure on grid operation by reducing the grid connection of distributed power sources through the "self-consumption" policy on the other.
The comparison of feed-in tariffs for different types of distributed PV construction from 2007 to 2011 is shown in Fig.
2000, 2004, 2010, 2012, 2014 several times to amend the renewable energy law; subsidies gradually reduced, the larger the capacity of the subsidy is less; encourage self-generation and local consumption, subsidize the light storage system.
May 1, 2013 came into effect, marking the expansion of Germany's distributed PV policy from subsidizing only power generation units to subsidizing energy storage units that safeguard PV power generation. The policy is only for PV facilities smaller than 30kW and provides for subsidies of up to 600 euros for the simultaneous construction of storage facilities for new PV installations and up to 660 euros per kilowatt for the retrofitting of storage facilities for existing PV. Germany, which announced the abandonment of nuclear energy, plans to increase the proportion of renewable energy to 35% by 2020, and to 80% by 2050.
Existing subsidies: Light and storage demand triggered by electricity market reform - incremental distribution grid, multi-energy complementary
Summarize
1, Germany's PV today is China's PV tomorrow
2, 531 policy can not change the trend of rapid development of commercial and industrial distributed photovoltaic
3, the rapid development of high proportion of distributed photovoltaic triggered the need for the development of optical storage
4, the rapid decline in the cost of photovoltaic and energy storage makes the development of optical storage exists economic feasibility
5, light - storage depth of integration is the development direction of the consumption of high-permeability distributed photovoltaic
