An abnormality determination system includes a power generation amount measurement unit that measures a power generation amount of the photovoltaic facility; a data acquisition unit that acquires data of a solar radiation amount; a calculation unit that divides a summed value of the power generation amount per day by a summed value of the solar radiation amount per day to calculates a division value; and a data accumulation unit that accumulates a combination of the power generation amount and the solar radiation amount, or the division value, and is configured to determine that there is an abnormality based on a slope of the division values.

One example method includes obtaining output powers at initial scanning points of photovoltaic strings in a first group and a second group. The output powers at the initial scan points of the photovoltaic strings in the first group can then be controlled to sequentially decrease, and the output powers at the initial scan points of the photovoltaic strings in the second group can then be controlled to sequentially increase. Scanning can then be performed in the initial scanning direction starting from output voltages corresponding to the output powers at the initial scan points of the first group. Scanning can then be performed in the initial scanning direction starting from output voltages corresponding to the output powers at the initial scan points of the second group, where output powers of the first group and the second group are kept to compensate each other during IV curve scanning.

One example method includes obtaining output powers at initial scanning points of photovoltaic strings in a first group and a second group. The output powers at the initial scan points of the photovoltaic strings in the first group can then be controlled to sequentially decrease, and the output powers at the initial scan points of the photovoltaic strings in the second group can then be controlled to sequentially increase. Scanning can then be performed in the initial scanning direction starting from output voltages corresponding to the output powers at the initial scan points of the first group. Scanning can then be performed in the initial scanning direction starting from output voltages corresponding to the output powers at the initial scan points of the second group, where output powers of the first group and the second group are kept to compensate each other during IV curve scanning.

A method includes generating a time-varying charge/discharge control signal for an electrical storage device, wherein generating the time-varying charge/discharge control signal comprises identifying a prioritization order of a stack of simultaneously operating control modes, the stack of simultaneously operating control modes including a staging mode and at least two additional control modes, each control mode of the stack comprising a plurality of control signal candidate values; identifying an intersection of one or more control signal candidate values from the plurality of control signal candidate values of each control mode of the stack according to the prioritization order; and determining, based on the prioritization order, at least one time-varying charge/discharge control signal for the electrical energy storage device from the intersection of control signal candidate values.

A method includes generating a time-varying charge/discharge control signal for an electrical storage device, wherein generating the time-varying charge/discharge control signal comprises identifying a prioritization order of a stack of simultaneously operating control modes, the stack of simultaneously operating control modes including a staging mode and at least two additional control modes, each control mode of the stack comprising a plurality of control signal candidate values; identifying an intersection of one or more control signal candidate values from the plurality of control signal candidate values of each control mode of the stack according to the prioritization order; and determining, based on the prioritization order, at least one time-varying charge/discharge control signal for the electrical energy storage device from the intersection of control signal candidate values.

The invention discloses an islanding detection method in DC microgrids based on MPPT trapezoidal voltage disturbance. The steps are as follows: start the MPPT strategy; set the starting signal threshold of disturbance; measure the output current of PVA at the maximum power; calculate the same environmental factor of PVA with different capacities under the same light intensity and temperature in real time; when the environmental factor is greater than the starting signal threshold of the disturbance, periodic trapezoidal disturbance is carried out to the PVA port voltage reference; if the PCC voltage Upcc exceeds the threshold set by the passive method, it is judged as islanding; otherwise, it is judged whether the change rule of Upcc is consistent with the change rule of the calculated PCC voltage Upccp under the trapezoidal disturbance; If it is consistent, it is judged as islanding; otherwise, it is pseudo islanding.

The invention discloses an islanding detection method in DC microgrids based on MPPT trapezoidal voltage disturbance. The steps are as follows: start the MPPT strategy; set the starting signal threshold of disturbance; measure the output current of PVA at the maximum power; calculate the same environmental factor of PVA with different capacities under the same light intensity and temperature in real time; when the environmental factor is greater than the starting signal threshold of the disturbance, periodic trapezoidal disturbance is carried out to the PVA port voltage reference; if the PCC voltage Upcc exceeds the threshold set by the passive method, it is judged as islanding; otherwise, it is judged whether the change rule of Upcc is consistent with the change rule of the calculated PCC voltage Upccp under the trapezoidal disturbance; If it is consistent, it is judged as islanding; otherwise, it is pseudo islanding.

A system includes a tracker configured to collect solar irradiance and attached to a rotational mechanism for changing a plane of the tracker and a controller. The controller is programmed to store a plurality of positional and solar tracking information and detect a first amount of DHI and a first amount of DNI at a first specific point in time. If the first amount of SHI exceeds the first amount of DNI, the controller is programmed to calculate a first angle for the tracker to maximize an amount of irradiance received by the tracker. Otherwise, the controller is programmed to calculate the first angle for the tracker based on a position of the sun associated with the first specific point in time and the plurality of positional and solar tracking information.

A system includes a tracker configured to collect solar irradiance and attached to a rotational mechanism for changing a plane of the tracker and a controller. The controller is programmed to store a plurality of positional and solar tracking information and detect a first amount of DHI and a first amount of DNI at a first specific point in time. If the first amount of SHI exceeds the first amount of DNI, the controller is programmed to calculate a first angle for the tracker to maximize an amount of irradiance received by the tracker. Otherwise, the controller is programmed to calculate the first angle for the tracker based on a position of the sun associated with the first specific point in time and the plurality of positional and solar tracking information.

A method for detecting a potential-induced degradation (PID) of PV modules of a PV installation includes operating a PV generator at a maximum power point (MPP), at a first generator voltage (U.sub.1) and first generator current (I.sub.1), and at a second generator voltage (U.sub.2) and second generator current (I.sub.2), where a first power (P.sub.1) at the first generator voltage (U.sub.1) is in a predefined first ratio V.sub.1=P.sub.1/P.sub.MPP and V.sub.1≤1, with the power (P.sub.MPP) at the maximum power point (MPP) of the PV generator, and where a second power (P.sub.2) at the second generator voltage (U.sub.2) is in a predefined second ratio V.sub.2=P.sub.2/P.sub.1 and V.sub.2<1, with the first power (P.sub.1) of the PV generator, and where a quantity Y that characterizes a progress of the potential-induced degradation (PID) is determined from the values of the voltages (U.sub.1, U.sub.2) and/or the currents (I.sub.1, I.sub.2).