GUARANTEED ORIGIN OF ELECTRICITY IN THE LOCAL POWER SYSTEM WITH RENEWABLE ENERGY SOURCES

Abstract

The article is focused on the development of a method for determining the part of electricity generated by renewable energy sources (RES) in the electricity flows in the branches of the electric grid. The method is based on a mathematical model of the electric grid, in which the coefficients of current distribution in the branches of the circuit from RES nodes and nodal voltages are used to determine the electricity flows in the branches of the electric grid. As a result, a matrix of power distribution coefficients of RES generation units to load nodes of the power grid is formed. This way, the component of the load power that depends on the power in the RES nodes is determined. The voltages used to form the RES power distribution matrix are determined based on the results of calculating the steady-state modes of the power grid or on the measurement data of the ACEMS.

Since the forming of local electric power systems (LES) based on RES is actual, the article considers LES as a balancing group within the electric power system (EPS), which can operate as an autonomous system according to certain conditions. It is shown that for this purpose, a RES reservation system should be created in the power system due to their dependence on natural conditions and, accordingly, the instability of their electricity generation. When a transmission system operates as part of an EPS, a general system reserve is usually used (mainly maneuverable capacities of thermal and hydroelectric power plants). In order for the LES can operate as an autonomous one, it is proposed to use other means of power reserve available today: electrochemical energy storage, hydrogen and biogas technologies. An effective way is to coordinate the schedules of RES generation in the LES with the load schedules of active consumers.

The example shows that in the case of a power deficit in the LES, RES located in the power grid can be used. The values of the necessary power at the LES connection node, power flows in the branches connecting the LES and RES grid, and power losses in them are determined by the offered method.