Overload and overvoltage in low-voltage and medium-voltage networks due to renewable energy – some illustrative case studies

• This paper quantifies the impact of curtailment of wind or solar power on energy absorbed by power distribution networks.
• Measured variations in consumption are used for all case studies as well as measured variations in production for one case.
• A distinction is made between “hard” and “soft” curtailment and their influence on the amount of curtailed energy is shown.
• For each of the case studies, technical implementation issues and communication needs are discussed.
• The paper contains a discussion on risks and economic trade-offs related to curtailment of renewable electricity production.

This paper presents the use of curtailment to allow more wind or solar power to be connected to a distribution network when overcurrent or overvoltage set a limit. Four case studies, all based on measurements, are presented. In all cases the hosting capacity method is used to quantify the gain in produced energy for increased levels of distributed renewable energy resources. A distinction is made between “hard curtailment” where all production is disconnected when overcurrent and overvoltage limits are exceeded and “soft curtailment” where the amount of production to be disconnected is minimized. It is shown that the type of curtailment method used has a large impact on the amount of delivered energy to the grid. The paper further discusses details of the curtailment algorithm, alternatives to curtailment, the communication needs and risks associated with the use of curtailment.