Model predictive controller for autonomous hybrid microgrids
AssigneesState Grid Corporation of China, Geiri Co., Ltd, State Grid Jiangxi Electric Power Co.
InventorsZhehan Yi, Yishen Wang, Bibin Huang, Di Shi, Zhiwei Wang, Tingting Hou
Life of this patent
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Abstract
A control system is disclosed with a control strategy for autonomous multi-bus hybrid microgrids based on Finite-Control-Set Model Predictive Control (FCS-MPC). The control loops are expedited by predicting the future states and determining the optimal control action before switching signals are sent to converters/inverters. The method eliminates PI and PWM components, and offers 1) accurate PV maximum power point tracking (MPPT) and battery charging/discharging control, 2) DC and AC bus voltage/frequency regulation, and 3) precise and flexible power sharing control among multiple DERs.
Claims17
A method for controlling a microgrid, comprising:
- collecting power data from a multi-bus hybrid microgrid, wherein the multi-bus hybrid microgrid comprises at least a converter or an inverter;
- predicting one or more future states of the microgrid from present and past states of the microgrid;
- determining a predetermined control action before switching signals are sent to the converter or inverter using Finite-Control-Set Model Predictive Control (FCS-MPC) during autonomous mode by switching a circuit breaker at a point of common coupling (PCC), wherein the VSI is a three-phase two-level inverter with three legs and two switches in each leg;
- and
- predicting next PV power as:
- PPV,1(k+1)=IPV,1(k+1)·VPV,1(k+1)
- PPV,0(k+1)=IPV,0(k+1)·VPV,0(k+1),
- where PPV,1 (k+1) and PPV,0(k+1) are next-step predictions of PV power when a converter switch is “ON” and “OFF”, respectively, IPV,1(k+1) and IPV,0(k+1) are next-step predictions of PV current when the converter switch is “ON” and “OFF”, respectively, VPV,1(k+1) and VPV,0(k+1) are next-step predictions of PV voltage when the converter switch is “ON” and “OFF”, respectively, and k is a discrete control step sequence.
A method for controlling a microgrid, comprising:
- collecting power data from a multi-bus hybrid microgrid, wherein the multi-bus hybrid microgrid comprises at least a converter or an inverter;
- predicting one or more future states of the microgrid from present and past states of the microgrid;
- determining a predetermined control action before switching signals are sent to the converter or inverter using Finite-Control-Set Model Predictive Control (FCS-MPC) during autonomous mode by switching a circuit breaker at a point of common coupling (PCC), wherein the VSI is a three-phase two-level inverter with three legs and two switches in each leg;
- and
- predicting an output voltage of a converter with a DC bus voltage, when a switching signals S(Sbat1,Sbat2) equal (1,0) and (0,1), by determining:
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- where Ibat (k), Io (k) and VDC (k) are battery current, converter output current and DC bus voltage, respectively, TS is a sampling time, Cbat is a converter output filter capacitance, VS=(1,0)DC(k+1) and VS=(0,1)DC(k+1) are predictions of a DC bus voltage when switching signals S(Sbat1,Sbat2) equal (1,0) and (0,1), respectively, and k is a discrete control step sequence.
A method for controlling a microgrid, comprising:
- collecting power data from a multi-bus hybrid microgrid, wherein the multi-bus hybrid microgrid comprises at least a converter or an inverter;
- predicting one or more future states of the microgrid from present and past states of the microgrid;
- and
- determining a predetermined control action before switching signals are sent to the converter or inverter using Finite-Control-Set Model Predictive Control (FCS-MPC) during autonomous mode by switching a circuit breaker at a point of common coupling (PCC), wherein the VSI is a three-phase two-level inverter with three legs and two switches in each leg, further comprising predicting voltage at the PCC (common bus) as:
- vPCC(k+1)=iPCC(k+1)·ZAC=[iT1(k+1)+iT2(k+1)]·ZAC.
- where ZAC is a common load impedance at PCC, vPCC (k+1) is a next-step prediction of PCC voltage, iPCC (k+1) is a next-step prediction of a common load current, and iT1 (k+1) and iT2(k+1) are currents flowing from Bus 1 and Bus 2 to PCC, respectively.
Dependencies are inferred from the claim text.