A variety of charge extraction (CE) techniques have been developed to measure charge density and recombination coefficients in bulk heterojuction (BHJ) solar cells. Charge recombination during charge extraction as a major limitation of this method has not been systematically quantified. Herein, we report CE measurements using a newly designed fast switch, which enables the application of a reverse bias to the solar cells facilitating charge extraction. With applied reverse bias, more than 40 % increase in the extracted charge was obtained in solar cells with thicker active layers or with fast recombination. The measured charge carrier lifetime increased by up to a factor of three at sufficiently high applied biases (up to 8 V), suggesting significant errors in CE measurements without applied bias. The increased extracted charges with increasing applied bias are attributed to a combination of three cases: i) slightly faster charge extraction due to the larger electric field; ii) increased charge extraction rate at high light intensities when the transients are space charge disturbed; iii) increased charge separated lifetime during charge extraction attributed to the spatial separation of the electron and hole density due to the applied electric field.

The Customer Dissatisfaction Index (CDI) concept, developed in 2006 by Vattenfall and STRI [1], introduces the service level compliance put into figures in network planning. By using the performance in a load point and the probability that a preset "dissatisfaction" level of security of supply is not fulfilled, it presents a more understandable customer focus. This was presented in an earlier CIRED report. [4] A pilot network planning case in a rural network in Finland near Jyväskylä has been performed as a pilot. Two different levels of satisfaction criteria has been used one for domestic customers (max 8 hours or 3 interruptions) and one for preferred customers such as industry, hospitals, nursing homes, supermarkets etc. (max 1hour or2 interruptions) (fig 1

In this paper novel cloud based fleet analytics was utilized for advanced asset management. The target was to optimize the maintenance and testing procedures of the secondary system in primary distribution substations. In the case study a series of 3007 different fault cases were automatically analysed in the cloud environment, gathered from 51 substation from the period of 18 months, containing both SCADA events and disturbance records. The result of the analysis was that 68% of the required secondary testing was actually tested already during the normal operation of the network, leaving only 32% that still need dedicated manual testing.

Maintenance inspection has an important role for distribution network companies. Inspections should be homogeneous and cost-efficient, and, at the same time, additional values should be created where possible. Elenia Oy has made use of an aerial photography system for its overhead line medium and high voltage network. Clear benefits and additional values are observed with the technique. This paper presents experiences and benefits that Elenia has gained from this. Aerial photography is a more cost-efficient inspection technique than traditional walking inspection, and it offers additional values of scale for the Elenia organization and its partnership network in a variety of areas.

The driving forces for increasing automation in all distribution network levels are the need to improve the reliability of the power supply for customers, requirement to improve the operational efficiency of the network company and the increased amount of distributed energy resources. This paper presents an approach how operation of the distribution network is improved with the increasing of the automation level in secondary substations. The paper presents also a method for reliable fault indication and restoration in compensated and high-ohmic networks.