Abstract
The increasing penetration of variable renewable energy sources (RES) such as wind power and photovoltaic cell in the microgrid poses a great threat to the power balance. The microgrid operator has to consider the system operational flexibility in the dispatch to overcome the uncertainties. For a multi-energy microgrid, the coupling relationship and complementarity of different energy provides potential capacity for operational flexibility. In this paper, we propose an operational flexibility metric to quantify the ability of the combined heat and power (CHP) microgrid to overcome RES uncertainties in operation. An intraday rolling dispatch strategy for the off-grid CHP microgrid is proposed, which consists of a dispatch decision (DD) stage and a real-time adjustment (RTA) stage. The operational flexibility constraints are incorporated in the DD model to ensure that the uncertainties in the real-time operation can be suppressed. The RTA model is based on a linear programming model. Case studies demonstrate that the proposed dispatch strategy can overcome the uncertainties efficiently and ensure the secure and economic operation of the system.
Highlights
The depletion of traditional fossil fuels and serious environmental pollution make the renewable energy source (RES) play an essential role in the future energy system [1], [2]
An intraday rolling dispatch strategy combining a dispatch decision stage and a real-time adjustment stage is proposed for the off-grid combined heat and power (CHP) microgrid
The case studies demonstrate that our strategy can accommodate the uncertainties electrical power and ensure the secure and economic operation of the CHP microgrid
Summary
Length of time interval of real-time adjust stage ηgt ηloss ηhr ηeh ηgb ηhe σbt ηbt,chr , ηbt,dis ξeh Efficiency of gas turbine Energy loss rate of gas turbine Efficiency of heat recovery unit Efficiency of electrical boiler Efficiency of gas boiler Efficiency of heating exchange device Self-charging rate of battery Charging/discharing efficiency of battery Adjustable ratio of power of electrical boiler ξgb Adjustable ratio of power of gas boiler. The associate editor coordinating the review of this manuscript and approving it for publication was Yunfeng Wen. Ramping rate of gas turbine (kW/h) Upper limit of power of electrical boiler (kW) Upper limit of power of gas boiler (kW) Upper limit of heat recovery unit (kW) Upper limit of power of heat exchange device(kW) Upper limit of charging/discharging power of battery (kW) Energy capacity of battery (kWh) Upper limit of charging/discharging power of thermal storage tank (kW) Energy capacity of thermal storage tank (kWh) Ramping up/down capacity of gas turbine at period t (kW) Ramping up/down capacity of electrical boiler at period t (kW) Ramping up/down capacity of battery at period t (kW) Ramping up/down capacity of gas boiler at period t (kW). Forecast value of electrical load at period t (kW) Expected forecast error of RES power Expected forecast error of electrical load Fluctuation value of RES power at period τ (kW) Fluctuation value of electrical load at period τ (kW) Fluctuation value of net electrical load at period τ (kW)
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