With the large-scale integration of distributed energy, the distribution network faces overvoltage, undervoltage, and voltage fluctuation issues brought about by distributed energy. Flexible loads can participate in distribution network regulation through time shifting, but flexible loads have characteristics such as small individual capacity, dispersed location, and involvement of user privacy, which require centralized control. Virtual power plant (VPP) can be used to coordinate and control various distributed energy sources and flexible loads. Typically, VPP focus more on commercial profit and do not fully consider the technical constraints of the system. Technical virtual power plants (TVPP) can pay attention to the technical constraints of the system while considering commercial profit. However, when flexible loads participate in the scheduling of technical TVPP, user privacy cannot be protected. To address this, a flexible virtual battery model that aggregates multiple flexible loads is proposed. By equating flexible loads to virtual batteries, the regulation capacity of flexible loads can be quantified while protecting user privacy. This model is tested through the IEEE 33-bus test system. The results show that, on the premise of protecting user privacy, the technical virtual power plant can regulate the voltage quality of the distribution network through flexible virtual batteries, while considering the distribution network loss situation.