Abstract: This application discloses a battery system and an energy storage container. The battery system includes a plurality of battery packs that are connected in series. Each battery pack corresponds to one first switch that is connected in series to the battery pack. Each battery pack corresponds to one second switch that is connected in parallel to the battery pack. Each battery pack is connected in series to the corresponding first switch and then connected in parallel to the second switch. The first switch includes a plurality of controllable switching transistors that are connected in parallel. The second switch includes a plurality of controllable switching transistors that are connected in parallel. The plurality of controllable switching transistors included in the first switch correspond to at least two different turn-on moments. The plurality of controllable switching transistors included in the second switch correspond to at least two different turn-on moments.

Abstract: An energy storage apparatus, including a plurality of battery modules, a switch unit, a start unit; and an electrical energy output port. The energy storage apparatus is configured for use in a photovoltaic power generation system having a plurality of photovoltaic modules, a direct current-to-direct current (DC/DC) converter, and a direct current-to-alternating current (DC/AC) converter. The plurality of battery modules is separately connected to the start unit and the switch unit, and the plurality of battery modules are configured to, when the start unit receives a start signal, control the switch unit to be turned on. The energy storage apparatus is configured to, in response to the switch unit being turned on, output electrical energy of the plurality of battery modules through the electrical energy output port, and, in response to the switch unit being turned off, disconnect the plurality of battery modules from the electrical energy output port.

Abstract: A photovoltaic energy system and a method for detecting a ground insulation impedance, improve accuracy of detecting a ground insulation impedance after one or more conversion circuits are connected in parallel. The photovoltaic energy system includes one or more conversion circuits and a detection circuit. The detection circuit includes an alternating current signal source and a sampling resistor that are connected in series, a first sampling circuit, and a control circuit. The control circuit is configured to control the alternating current signal source to output harmonic signals of a first frequency and a second frequency. The first sampling circuit is configured to: when the alternating current signal source outputs the harmonic signal of the first frequency, collect a voltage at both terminals of the sampling resistor to obtain a first voltage.

Abstract: A photovoltaic energy system and a method for detecting a ground insulation impedance, improve accuracy of detecting a ground insulation impedance after one or more conversion circuits are connected in parallel. The photovoltaic energy system includes one or more conversion circuits and a detection circuit. The detection circuit includes an alternating current signal source and a sampling resistor that are connected in series, a first sampling circuit, and a control circuit. The control circuit is configured to control the alternating current signal source to output harmonic signals of a first frequency and a second frequency. The first sampling circuit is configured to: when the alternating current signal source outputs the harmonic signal of the first frequency, collect a voltage at both terminals of the sampling resistor to obtain a first voltage.

Abstract: An energy storage system and a method for controlling an the energy storage system, includes a plurality of energy storage units. The energy storage unit includes a plurality of battery cells, a plurality of balancing units, a voltage conversion unit, a first switch, a second switch, and a control unit. The control unit is configured to detect fault cases of the plurality of battery cells, and control open and closed states of the first switch and the second switch. According to the application, it can be ensured that each energy storage unit in the energy storage system can continuously work when a battery cell is faulty and when state of charge balance between battery cells is implemented, thereby greatly improving reliability of the energy storage system with low costs.

Abstract: An energy storage system, to improve operating efficiency and system reliability that exist when a component in the energy storage system is faulty, and avoid a waste of resources. The energy storage system includes a plurality of energy storage branches, at least one switch unit, and a control circuit. Each of the energy storage branches includes a first bus, a string-level converter, and a battery string that are sequentially connected in series, a plurality of balancing converters, and a shared bus. The battery string includes a plurality of battery units connected in series, and each of the battery units includes one battery pack. The battery pack is connected to an input side of one corresponding balancing converter, and output sides of the plurality of balancing converters are separately connected to the shared bus.

Abstract: A low density, high-strength, degradable temporary plugging agent which includes 60% by weight to 85% by weight of polylactic acid, 5% by weight to 20% by weight of a starch, 5% by weight to 10% by weight of polycaprolactone, 2% by weight to 5% by weight of a solubilizing agent, and 2% by weight to 5% by weight of a toughening agent, based on 100% by weight of the total weight of the agent. The rigid agent can result in bridge plugging in existing cracks, with a significant increase in pressure. The preparation method is simple, the process requirements are low, and industrial production can be realized. When applied to temporary plugging fracturing, under formation conditions, it can be completely degraded within a certain period of time and will not cause secondary damage to the reservoir, while preventing the agent from polluting the formation and the occurrence of pump accidents.

Abstract: A low density, high-strength, degradable temporary plugging agent which includes 60% by weight to 85% by weight of polylactic acid, 5% by weight to 20% by weight of a starch, 5% by weight to 10% by weight of polycaprolactone, 2% by weight to 5% by weight of a solubilizing agent, and 2% by weight to 5% by weight of a toughening agent, based on 100% by weight of the total weight of the agent. The rigid agent can result in bridge plugging in existing cracks, with a significant increase in pressure. The preparation method is simple, the process requirements are low, and industrial production can be realized. When applied to temporary plugging fracturing, under formation conditions, it can be completely degraded within a certain period of time and will not cause secondary damage to the reservoir, while preventing the agent from polluting the formation and the occurrence of pump accidents.