Methods for joint power flow calculation of master-slave systems based on grid-following impedance

A system for joint power flow calculation of master-slave systems based on grid-following impedance, including:

• a system partition module, configured to:
• divide a power system into a master system and at least one slave system, and determine a boundary node;
• add a virtual slack node in the at least one slave system, and set grid-following impedance between the virtual slack node and the boundary node to constitute a virtual slave system;
• an initial value calculation module, configured to:
• set a voltage of the boundary node as an initial value, calculate power flow of the at least one slave system, and obtain slave system power of the boundary node;
• a master system calculation module, configured to:
• set power of the boundary node as the slave system power, calculate power flow of the master system, obtain the voltage of the boundary node and a corresponding element between a voltage magnitude correction value of the boundary node and an active power imbalance of the boundary node, and a corresponding element between the voltage magnitude correction value of the boundary node and a reactive power imbalance of the boundary node in an inverse Jacobian matrix calculated based on the power flow of the master system;
• an impedance determination module, configured to:
• according to the corresponding elements of the inverse Jacobian matrix, the voltage of the boundary node, and the slave system power, calculate a resistance value and a reactance value of the grid-following impedance, and calculate a voltage of the virtual slack node;
• a virtual power flow module, configured to:
• calculate power flow of the virtual slave system based on the grid-following impedance and the voltage of the virtual slack node, and obtain new slave system power from the boundary node;
• a convergence determination module, configured to:
• determine whether the voltage of the boundary node, an active power of the boundary node, and a reactive power of the boundary node satisfy a convergence condition, and in response to determining that the convergence condition is satisfied, end the calculation, or in response to determining that the convergence condition is not satisfied, return to step S3 to continue iteration;
• wherein the resistance value of the grid-following impedance is determined by multiplying the voltage of the boundary node by the corresponding element between the voltage magnitude correction value of the boundary node and the active power imbalance of the boundary node in the inverse Jacobian matrix;
• and the reactance value of the grid-following impedance is determined by multiplying the voltage of the boundary node by the corresponding element between the voltage magnitude correction value of the boundary node and the reactive power imbalance of the boundary node in the inverse Jacobian matrix.