Strategic behaviour in flexibility markets: New games and sequencing options

Abstract

Distribution system operators are expected to procure flexibility when it is cheaper than expanding their distribution grid. How to integrate these flexibility markets in the existing sequence of electricity markets is an important open issue in the evolution of electricity markets in Europe. In this paper, we investigate four market sequencing options: (1) the nodal wholesale market that includes network constraints(WNC); (2) the zonal wholesale market without network constraints followed by an integrated redispatch market to remedy the network congestion at transmission and distribution level created by the wholesale market in a coordinated way (WIR); (3) the zonal wholesale market followed by separate flexibility, redispatch and balancing markets in that order, which implies that congestion at distribution level is treated before congestion at transmission level (WFRB); and (4) the zonal wholesale market followed by separate redispatch, flexibility and balancing markets in that alternative order, which implies that congestion at transmission level is managed before congestion at distribution level (WRFB). We analyse how changing the market sequence can impact the strategic behaviour of flexibility providers, here represented by a Balancing Responsible Party (BRP). We introduce a bi-level model in which the strategic BRP in the upper level acts as a first mover that anticipates the effect of its offers on the market outcome of the lower-level optimization problems. In analogy with the inc-dec game triggered by redispatch markets, we find that flexibility markets can trigger new games. These games will be difficult to detect by regulators as they can be performed by relatively small players. We observe that the WNC market design clearly outperforms the other sequencing options, but there is no clear second best among the alternatives WIR, WFRB, and WRFB.