A method for operating an inverter includes applying, via a switching unit of the inverter, an AC voltage to a phase line in which a filter inductor is arranged, determining a coil current (i.sub.L) of the filter inductor and determining a coil voltage (u.sub.L) of the filter inductor, determining a first value (L(I.sub.X)) of the filter inductor for a first value determining an inductance profile of the filter inductor with respect to the coil current, using the determined first value of the filter inductance and optionally using the at least one determined further value of the filter inductance, and controlling the switching unit of the inverter, via a control unit, to generate an alternating current in the phase line. At least one parameter of the control process is continuously adapted to the momentary coil current according to the determined current-dependent inductance profile.

To allow reliable current measurement of the output current of the switching stage of an inverter, especially at switching frequencies of the semiconductor switches in the 100 kHz range, a voltage at the choke is measured and integrated over time to be representative for the leg current in the choke. The time integral is processed in a processing unit, whereas the processed time integral is used in an inverter controller for controlling the inverter. The voltage at the choke is analogously integrated over time by two serially connected integrator capacitors, whereas across each of the integrator capacitors a reset switch is provided, for alternately resetting the corresponding integrator capacitor.

Embodiments of this application provide a power system. An output terminal of a power supply or a DC-to-DC unit is cascaded. In addition, according to the power system provided in embodiments of this application, a quantity of cables from the power supply or the DC-to-DC unit to the DC-to-AC unit may be further reduced by cascading an output terminal of the power supply or the DC-to-DC unit and cascading an input of the DC-to-AC unit.

The present invention relates to an aggregation method for dispatching the wind and solar power plants. The primary technical solutions include: introducing the power output complementarity indexes to characterize the average effect of the degree of power output complementarity between different power stations, using cohesive hierarchical clustering to identify the optimal cluster division under different division quantities, and introducing the economic efficiency theory to determine the optimal cluster quantity, which avoids the randomness and irrationality that may result from relying on the subjective determination of the number of clusters. According to the analysis of dozens of real-world wind and solar power cluster engineering in the Yunnan Power Grid, the results show that the invention can effectively reduce the number of directly dispatched power stations, and the uncertainty of wind and solar power output can be more accurately described in a cluster manner, presenting better reliability, concentration, and practicality.

A method for describing power output of a cluster of wind and solar power stations considering time-varying characteristics. The error function is employed to characterize the degree of difference in power output within periods, and split-level clustering is used to determine the optimal period division under different period division quantities. The economic efficiency theory is introduced to determine the ideal number of periods, avoiding the randomness and unreasonableness that may result from relying on the subjective determination of the number of clusters. This method can reasonably divide the wind and solar power output period, fully reflecting the time-varying law of wind and solar power generation. The results also can accurately reflect the distribution characteristics of the power output of the power station group at each time period, and the power output each time period shows better reliability, concentration, and practicality.

Disclosed herein are systems and methods for sliding mode control enabled hybrid energy storage. In a specific embodiment, the system can include: a photovoltaic power generation unit; a hybrid energy storage system, where the hybrid storage system can include a battery, a supercapacitor, where the supercapacitor provides excess power demand based on different loading conditions, and a rate limiter; a sliding mode controller, where the slide mode controller controls a current in a hybrid energy storage system; a supercapacitor charging control; and a proportional integral controller. In a specific embodiment, the method can include: decoupling an average and transient hybrid energy storage system current with a single rate limiter, where the decoupling includes a battery discharge rate; regulating a battery current with a first sliding mode controller; and regulating a supercapacitor current with a second sliding mode controller, where a supercapacitor provides excess power demand.

A distributed power system including multiple DC power sources and multiple power modules. The power modules include inputs coupled respectively to the DC power sources and outputs coupled in series to form a serial string. An inverter is coupled to the serial string. The inverter converts power input from the serial string to output power. A signaling mechanism between the inverter and the power module is adapted for controlling operation of the power modules.

Ultra-high accuracy elevation and pressure telemetry devices are used to develop an autonomous, self-calibrating hydraulic piping network computer simulation model. Virtual pressure reducing valve (PRV) model elements force a local downstream calibration of the model using the pressure telemetry data, overcoming the potential ill conditioned state when simulating wide ranging, real world operational conditions. This technique also creates a smaller solution set for calibration optimization algorithms such as machine learning. Additional benefits of this technique include the ability to ignore complex facilities such as pump stations, water storage tanks, and control valves enabling a more rapid development of the real-time water piping network computer simulation model.

A frequency stabilization arrangement for a power transmission grid has a modular multi-level converter with a first terminal for electrical connection to a power transmission grid, and an electrical resistor unit with a second terminal for electrical connection to the power transmission grid.

The present disclosure provides systems and methods for flexible renewable energy power generation. The present disclosure also provides systems and methods for firming power generation from multiple renewable energy sources.