Aiming at the problem that voltage quality affects normal release of user load, in order to quantitatively measure the influence of voltage quality, this paper proposes an estimation method of low voltage type hidden energy not supplied based on electric energy data. Firstly, the relationship between voltage deviation and user side power supply reliability is discussed from the perspective of power consumption, as well as the concept and value of hidden energy not supplied. Secondly, the hidden energy not supplied estimation method is proposed. The time-varying and power quality sensitivity of user load is considered, and the time-division static active load model of different types of user is constructed from the two dimensions of time and voltage. Then, this load model is used to estimate the hidden energy not supplied and electricity shortage ratio of various users, to measure the influence degree of low voltage on user side power supply reliability. Finally, an example proves that the method proposed in this paper shows practical application value.