Coal power is a traditional flexible resource. In the process of transformation from basic guarantee power to system regulation power

it is necessary to coordinate the relationship between new

in-service and ageing coal power units to solve the problem of insufficient power supply or new energy consumption caused by insufficient flexibility. Therefore

a collaborative planning method of flexible resources considering the transformation of coal-fired power units in typical and extreme scenarios is proposed

which realizes the improvement of flexibility in multi-scenarios. In this paper

a coal-fired power transformation model including flexibility transformation of in-service coal-fired power units

retirement

life extension and emergency reserve of ageing coal-fired power units is established and embedded in the adjustment ability and cost model of source-grid-load-storage resources. Taking the transition path of coal power and the construction of other flexibility resources as decision variables

a collaborative planning model for source-grid-load-storage flexibility resources is proposed

which is based on the weights to realize the combination of typical and extreme multi-scenarios

and the two sub-models of iterative investment decision along with day-ahead intra-day operation optimization to realize an effective solution. Finally

taking the improved IEEE 24-bus system as an example

the spatial and temporal characteristics of the problem of insufficient flexibility in multi-scenarios are analyzed

and a collaborative increase in power system flexibility and economics is realized.