System Services

System Operation

System operation is a service provided by HOPS which includes planning, control and analysis of system performance, and monitoring and control of the power system in real time. System operation service as a non-attributable service is charged for through the charge for transmission network use. 
Congestion in the network occurs when loads approach the rated capacity of network elements. To maintain system security, HOPS in such circumstances must apply special measures to reduce loads in network elements: change power plants’ production, change the status of step up/down transformers and network switching status or change contractual schedules of market participants. This service as a non-attributable service is charged for through the charge for transmission network use. 

Voltage and Frequency Maintenance

The quality of electricity is expressed by the amount of voltage and frequency and by its wave shape. HOPS uses all available resources and methods to maintain electricity quality parameters within the allowed limits.
This service as a non-attributable service is charged for through the charge for network use.

System Restoration after Disturbance 

This service is provided by HOPS after a disturbance in the system causes a decreasing of quality of electricity, system elements to fail, partial or total blackout. HOPS applies the procedures prepared specifically for cases of disturbance. 
This service as a non-attributable service is charged for through the charge for network use.

Ancillary Services 

Those are available individual services provided by the system user (e.g. generator) or the Distribution System Operator upon the request of the Transmission System Operator for the provision of which (technical solution, operating costs) Transmission System Operator shall be adequately remunerated. Those services are used by the Transmission System Operator to provide system services.

Frequency Control

The ancillary service of system frequency control is provided through primary, secondary and tertiary control of generating units. The sole purpose of primary control is to control frequency while secondary and tertiary controls are used to control frequency and power. 

Voltage and Reactive Power Control

The purpose of this ancillary service is to maintain voltage in the power system within the allowed limits and to minimize flows of reactive power in the network. 
Voltage and reactive power control is carried out by regulating transformer transmission ratios, by using compensation devices and by producing reactive energy in power plants. 

Black Start of Power Plants

This ancillary service represents the capability of a generating plant to start up its generating units independently, without any external electricity supply. This ancillary service is paid by HOPS to power plants which have the capability for black start. 

Island Operation

Island operation is the ancillary service which ensures the establishment of island operation of parts of the power system in case of disturbance or in case of major maintenance or reconstruction work. The purpose of this ancillary service is to minimize the time of disruption in supply to customers in extraordinary circumstances.