distribution grid expansion

The aim of this study is to conduct a structured, technical and economic comparison of different technologies using standard grids and local scenarios to find answers to the following three questions:

1. What challenges do appear in distribution grids now and in the future and what technologies can perceive grid support tasks?

2. Which contribution can be delivered by the individual technologies in comparison to each other and conventional grid extension to reduce the existing and the expected need of grid expansion?

3. What are the costs for the integration of new technologies and how much do they reduce the costs for conventional grid extension?

The approach of the analysis is based mainly on the development of distribution grids due to newly installed distributed generation systems. For this the German grid development plan was disaggregated into local generation patterns. In these local patterns, scenarios for energy generation development from renewable energy sources (photovoltaic, small wind turbines, combined heat and power and power plants, heat pumps and electric vehicles) were classified into “point clouds” covering power in KWp per device and penetration per house, as can be seen in figure 1.

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Figure 1: Formation of the local scenarios (left) and localization of the local scenarios (right) for the year 2034

In order to overcome expected conventional grid expansion, which states and adequate replacement of conventional cables, overhead lines and transformers,  several technology options (e.g. decentralized generation plants, rate Control, Cos φ (P) – Control, Q (V) – Control, P (V) – Control, PV systems and inverters, controllable distribution transformers, single strand regulators & battery storages) were qualitative and quantitative evaluated and added into a simulation model. In this model a practical assessment of technology options is based on results from 1.2 billion simulations, which produce and analyze average and extreme grid configurations in a sufficient bandwidth (for example under the permissible voltage fluctuations, allowable operational loads and the underlying type of grid). So for each type of grid and local scenario, the most appropriate technology option can be represented as an alternative to conventional grid extension.

The calculations of the expected grid conditions and the demand to expand the grids by using available technology options are done by probabilistic load flow simulations. It considers stochastic fluctuations, which in this case are the load and generation behavior of decentralized energy generation units, typical behavioral patterns of persons in households or weather-related fluctuations. In order to determine the necessary conventional grid expansion measures, a heuristic is used. It is a calculation using the Dijkstra-algorithm to determine the shortest route from the place of voltage band violation to the busbar.

The span of 13 local scenarios, ten grid types and nine technology options results in a high number of simulations with the probabilistic power flow calculations. The result area itself can be used for grid types, technologies (and local scenarios. Possible evaluation criteria are technical evaluation parameters such as resource utilization or node voltages and economic evaluation criteria such as technology, grid expansion or total costs.

The results of this study therefor are complex as many layers can be analyzed. However a summary can state that the costs for the inevitable grid expansion can be lowered from 40 per cent up to 100 per cent in comparison with conventional expansion measures, depending pf the underlying grid type. Expecting a nationwide distribution grid expansion cost through conventional measures between 3 billion up to 20 billion Euros (according to other studies), the saving potential using the technology options described would be huge not talking about benefits for the population avoiding the construction of new power lines.

For further information, a more detailed English abstract or the entire the P3 energy study (only available in German), send an email to P3_EAS_Verteilungsnetz@p3-group.com.

Written by Jonas Kampik and Philipp Ostman, P3 Group