ENERGY STORAGE SYSTEM COMPRISING MULTIPLE BATTERY PACKS

This application provides an electrical energy storage system and an energy storage system, to improve application flexibility of the electrical energy storage system. The electrical energy storage system includes: M battery packs; M first DC/DC converters, where first terminals of the M first DC/DC converters are respectively connected to the M battery packs, the M first DC/DC converters are classified into N first DC/DC converter sets, M is an integer greater than 1, and N is an integer greater than 0; and N second DC/DC converters, where the N second DC/DC converters one-to-one correspond to the N first DC/DC converter sets, a first terminal of each second DC/DC converter is connected to second terminals of all first DC/DC converters in a first DC/DC converter set corresponding to the second DC/DC converter, a second terminal of each second DC/DC converter is connected to a first interface of the electrical energy storage system, the first interface is configured to receive a direct current from a power generation system or output a direct current to the power generation system, and N is an integer greater than 1.