Test Case 15

15

Alkistis Kontou, Dimitris Lagos, Loizos Loizou

v03

ERIGRID 2.0

19/05/2021

Smart Grid Control Algorithm – optimal centralized Coordinated Voltage Control

Distribution networks are becoming increasingly “smarter”, as well as more complex, with the addition of power electronic devices, ICT, smart meters, and more. As a result, advanced control strategies to manage such networks are becoming necessary.

An optimal centralized Coordinated Voltage Control (CVC) operates as a distribution management system. The algorithm manages all the devices of the network that are capable of regulating the voltage either directly (OLTCs), or through the injection of active/reactive power, such as Battery Energy Storage Systems (BESS) and Photovoltaic (PV) inverters. Management is based on the solution of an optimization problem, which minimizes a predefined objective function, subject to linear and non-linear constraints.

A central controller is installed at substation level and is initialized with all the necessary static data of the network: network topology, admittance of lines and transformer, nominal power of DER units and storage systems, operating limits, tap change operations of the OLTC, etc. While it operates, it requests and receives real-time power measurements from the smart meters of loads and DER units, as well as the state of charge (SoC) of the storage systems and the current tap position of the OLTC. Using this dynamic data, it formulates the optimal power flow problem, whose objective function involves the minimization of voltage deviation of critical nodes from the nominal value, power losses of the lines and transformer, and tap change operations of the OLTC.

PV inverter’s Q(U) control, OLTC controlling secondary voltage, MGCC behavior

MicroGrid Central Controller (MGCC)

Electrical Power, ICT

• Characterization and validation of the SuT
• Verification and validation of the OuI
• Verification and validation of the FuT

PV, OLTC, transformer, distribution line, upstream network impedance, MGCC

Optimal centralized coordinated voltage control algorithm, Communication scheme

• OLTC behaviour according to reactive power levels
• Inverter’s effectiveness in participation in voltage regulation
• Inverter’s reaction to tap changes
• BESS management effectiveness
• Industrial MGCC behavior

1. When and how often the optimization converges. How fast and what is the solutions quality (suboptimal etc)
2. Voltage deviation of all the nodes from the nominal value, number of tap changes, network active power losses with and without the CVC algorithm
3. Estimation errors of voltage, active and reactive power
4. Ability of the BESS to provide voltage support (based on SoC)
5. Errors and failures and delays that the MGCC may introduce

• Load and RES Patterns (realistic, daily, annual variation)
• Message exchange of MGCC using different protocols (Modbus, IEC 61850)

1. Convergence of the optimization algorithm within some sec (validation)
2. All voltages are within ±5% of the nominal value (characterization)
3. Estimation quality characterized with a confidence of 95% (characterization)