Balancing Unpredictable Load and Intermittent Renewables by Semi-Dispatchable Distributed Generation

The paper presents a principle of a consequent hierarchical power and energy balancing in a power grid including a number of interconnected microgrids. Due to a load and intermittent energy sources output fluctuations, strong power and energy unbalances may arise in microgrids. These unbalances lead to inner and outer power and energy exchange that can be represented as the dispersion components of power and energy profiles. Compliance of the power balance is a part of microgrids' secondary power regulation aimed at Area control error and power exchange keep given the limited interconnection capacity. Compliance of energy balance is a part of tertiary power regulation. It is of great importance for market settlements. An approach to semi-dispatchable distributed generation utilization for decreasing the power and energy dispersions taken by microgrids' sources, and interconnecting microgrids power lines is considered. Different strategies of power and energy dispersions elimination applied to distinguishing load compositions are examined. An analysis show that generations' typical power level and ramping settings corresponding to steady-state equipment operation enable to reduce the dispersion components in a great extent, although not to eliminate them at all. A mechanism of financial incentives for decreasing power flows dispersions is developed. It is based on a discount for technological interconnection due to maximum load decrease or discount for energy exchange price due to power and energy losses decrease.