7.5 Existing activities to further knowledge on intermittent generation

In Denmark, EnergiMidt is developing the FUR Project as a ‘test lab’ where new products can be tested and developed [50]. The objectives of the project include to:

  • determine whether sample rate of 15-min or 1-min is required for load profiles
  • estimate the maximum allowable installed PV capacity, which will be determined by node voltage limits and thermal limits of transformers.

The FUR Project will utilise smart meters (already installed) and fibre optics for fast data transmission. Irradiance profiles will be sampled every minute.

In Japan, NEDO smart grids were trialled between 2002 and 2007 with the aim of developing technology to prevent restriction of PV output [53]. A photo showing a residential area in Japan with clustered PV power generation system can be seen in Figure 76.

Figure 76 Image of NEDO Smart Grid clustered PV

Storage was used to reduce reverse power flow and regulate voltage. The battery is charged when the PV output is larger than demand, and discharged when demand exceeds PV output. Results of the voltage control using storage are shown in Figure 77. A total of 553 PV units were installed on residential properties with an average capacity of 3.85 kW per installation [53]. The total installed PV capacity of the smart grid setup was 2.13 MW. Each installation was coupled with a 4 kVA inverter and lead-acid batteries, as seen in Figure 78. New anti-islanding detection techniques and methods to avoid anti-islanding interference amongst systems were developed.

Figure 77 Voltage control in NEDO Smart Grid clustered PV generation system

Figure 78 NEDO Smart Grid setup and characteristics

Japan is also running demonstration projects of renewables on islands with small independent grids. The list of islands with a breakdown of the different renewable sources and storage installations can be seen in Table 14. It is worth noting the large wind power capacity in the island of Yonaguni relative to its maximum demand. The objectives of these projects are to:

  • study the impacts on the system if large scale solar is introduced
  • calculate the level of solar penetration possible
  • acquire knowledge about grid stabilisation technologies
  • analyse operational data of solar generation and battery storage
  • test system stabilisation technologies.

Table 14 Japan’s island demonstration sites

Island Wind (kW) Solar (kW) Battery (kW) Max Demand (kW)
Miyako 4200 4000 4000 50000
Tarama 280 250 250 1160
Yonaguni 1200 150 150 2160
Kitadaito 0 140 100 860

Japan is implementing METI’s smart grid demonstration tests (2010 - 2012) by power utilities with the following objectives:

  • introduce a low carbon grid with massive renewable penetration
  • vision is to minimise CO2 emissions and social costs
  • look into possible impacts to power quality and security
  • discover ways to enhance power quality by making the grid and consumers smarter.

For these METI demonstrations, at the house level there will be:

  • weather forecasting
  • electric vehicles
  • PV/appliance optimisation
  • curtailment control.

Gas utilities in Japan and NEDO are also running a demonstration project to optimise the distributed energy management of co-generation and PV.

EDP of Portugal is investigating the impact of climate on the performance of commercial PV panels. Four locations with varying average temperatures, direct and indirect insolation have been selected [61]. The panels are also oriented in three ways, vertically (facade), horizontally and tilted.

EDP is also working with Siemens to test Molten Salt Technology at a CSP plant at the University of Evora and in is involved in smart grids through their InovGrid/InovCity project. The InovGrid project is exploring active participation of clients through the use of smart meters and energy efficient initiatives.