Solutions provided by the Regional Operation Centre Balancing Cockpit (ROC-BC)
The EU network code “Requirements for Generators” regulates the LFSM-O (Limited Frequency Sensitive Mode – Over-frequency). This mode is the basis for over-frequency protection (OFP) and refers to the effect achieved through turbine generators at certain over-frequencies to reduce the active power of production units, according to the given droop settings. On the other hand, the network code “Emergency and Restoration” allows for the OFP to be introduced alternatively by an automatic over-frequency control scheme.
The implemented centralised generator dynamic over frequency protection based on SCADA and WAMS (PMU) data within the ROC-BC product is the solution to establish an OFP system without LFSM-O.
The centralised generator OFP module calculates the generator over frequency settings in real-time based on the generator priority, active power, and droop setting. The solution is implemented on EMS (Serbian TSO) system. The system can send the command for disconnection of the generation directly to the generator. Another possibility is to send the OFP setting to the generator protection relay.
The figure below presents on the left side 24 hours period of four selected generators. The first chart presents the power system frequency, the second chart presents the total active power of all generators, the third chart presents the active power of each selected generator, and the fourth chart presents the frequency limit settings. On the right side of the figure is the table presenting the current values for the frequency limit settings, power to shed in %, and the operating power of each generator.