The high levels of renewable energy happened to contribute to this incident, but not because of something inherent in renewable energy. All renewable energy sources are connected to the grid through inverters, and in Spain most of these inverters do not use an adequate control policy, i.e. they do not compensate the phase fluctuations of the grid, like the synchronous electromechanical generators do (i.e. they do not generate an appropriate amount of reactive power for compensation).
Technically it is easy to implement such control policies in all solid-state inverters, but it was not done in Spain because there were no incentives, i.e. there were no regulations specifying how the inverters connected to the grid should behave, otherwise than disconnecting when the frequency went outside a permissible range.