The storage level of reservoir is essential for the power supply capability of high proportion hydro-power system. The quantitative method of storage value of reservoir widely used at present fails to objectively reflect its power supply support capability. To this end

a quantitative method of power supply capacity of high proportion hydro-power system considering multi-dimensional hydro-power constraints is proposed. Firstly

an effective storage level model of reservoir considering the influence of multiple constraints such as cascade coupling and transmission capacity is established. At the same time

a water-load joint probability model based Copula is developed

and on this basis

the demand assessment of hydro-power is realized based on time series production simulation. The index of the number of days of power supply for reservoirs is put forward

and the quantitative evaluation of power supply capacity is realized by combining the effective storage level and hydro-power generation demand. Finally

the actual system in Sichuan is taken as an example for verification

and the results demonstrate that the proposed method in this paper can directly and accurately quantify the power capacity of reservoirs

which is of great significance to guide the optimal operation and water storage strategy of power systems.