Abstract
This Electra internal report includes the work of Task T6.1 describing the nature, availability and
contribution of flexibility resources. This task also models the interactions across control
boundaries and identifies sources of control conflicts, giving also an overview of experiences from
the ELECTRA partners regarding the realization of controllers in demonstration and field test
projects. The work was carried out during the period from May to December 2014.
The different type of flexibility resources, their characteristics, affecting market mechanisms and
potential for aggregation were researched using a survey among project partners. The parameters
used to characterise flexibility include the amount of power modulation, the duration, the rate of
change, the response time, the location, the availability, the controllability, etc. Views were also
received how these parameters will develop until 2030 and what are the general trends for
development of amount and controllability of this resource types. The parameters characterising
different energy resources provide the technical requirements for their applicability to flexible
operation of the grid and their suitability for frequency and voltage control now and in the future.
Regarding the flexibility of electricity generation, gas turbines and other heat motors as
reciprocating engines can be started quickest. The speed of power change is clearly the highest for
heat motors and their minimum power is low. Also steam and combined heat and power plants
can be utilised in the relatively quick increasing of the electricity generation. Slower power changes
are possible also with the nuclear power but they cannot be carried out continuously. The
regulation characteristics of hydro power are superb in comparison to the other electricity
generation methods. Besides the sun power, wind power is increasing most quickly in the world in
the coming years. The modern wind power plants are able to active and reactive power control.
Storage systems can contribute to the frequency and voltage control mechanisms. Charging and
discharging of the storage system at the right moments (response within milli-seconds to seconds)
can help to preserve the balance between consumption and generation. Storages can also provide
secondary and tertiary frequency control. Static compensation devices maintain desired voltage
level by feeding the grid with necessary reactive power. FACTS devices and cross-border
connections based on HVDC converter schemes can play an important role in frequency and
voltage support. Demand response, including industrial loads and household devices and electric
vehicles, will have great influence in flexible operation of the grid.
This report describes appropriate models that characterize the interactions across control
boundaries under normal and emergency situations, introducing suitable data rates and models of
use by real-time control functions. In the future power system scheme, TSOs will be able to control
significantly smaller part of the generation compared to the traditional centralized configuration,
and thus they will not be able any more to compensate large deviations in the power balance.
Moreover, increased electricity loads and sources such as EVs and residential PV systems, will
influence the balance between day-ahead production and consumption schedule and will leave
energy markets with higher and less predictable need for balancing power. The actors involved in
the future grid control are balance responsible Party (BRP), cell system operator (CSO), cell
operational information system (COIS), distribution system operator (DSO). Their respective roles
are described and these actors play roles both to technical and market operations. Considering the
web of cells concept developed in this project, the generation units will be smaller and in many
cases these will be renewable resources which are less suitable for frequency control [1]. For that
reason a more important role for participation at the demand side will be expected for voltage and
frequency control in the future. The report describes “model based interfaces”, where the flexibility
user and the flexibility contributor agree on a simplified model which describes the actual behaviour
and constraints of the flexibility resource. Main outcomes of the work are the definition of controller conflict from a flexible power system perspective, a review of state of the art in power system control conflict and an outline of the methodology for identifying these conflicts during system operation and their impact on system stability. The report summaries the main findings from the literature and from project participant’s experience in terms of scenarios or examples of controller interactions resulting in conflict. A measure of controller conflict is presented for each example. This can be used as an indicator of the impact of controller conflict on system stability. Suggestions for resolving controller conflict are
also presented. The report describes the methodology proposed to construct such a dynamic
model for the purposes of extracting conflicting interactions of interest from the point of view
frequency and voltage stability. From the voltage stability perspective there are many factors which
may significantly influence the environment for voltage stability. It seems quite certain, that
possible conflicts affecting voltage stability may occur mainly due to lack of proper coordination
among players in the system voltage control and reactive power reserves management which are
TSOs, DSOs, Generators and Aggregators. Generally the scenery foreseen for frequency, voltage
and reactive power control in 2030+ is much more complicated than it is presently.
An overview of experiences from the ELECTRA partners regarding the realization of controllers in
demonstration and field test projects are also provided. It summarizes best practices and lessons
learned which will provide valuable inputs for the implementation of control concepts and their
testing and validation. The main requirements for controllers are reliability, fault tolerance and
robustness.
contribution of flexibility resources. This task also models the interactions across control
boundaries and identifies sources of control conflicts, giving also an overview of experiences from
the ELECTRA partners regarding the realization of controllers in demonstration and field test
projects. The work was carried out during the period from May to December 2014.
The different type of flexibility resources, their characteristics, affecting market mechanisms and
potential for aggregation were researched using a survey among project partners. The parameters
used to characterise flexibility include the amount of power modulation, the duration, the rate of
change, the response time, the location, the availability, the controllability, etc. Views were also
received how these parameters will develop until 2030 and what are the general trends for
development of amount and controllability of this resource types. The parameters characterising
different energy resources provide the technical requirements for their applicability to flexible
operation of the grid and their suitability for frequency and voltage control now and in the future.
Regarding the flexibility of electricity generation, gas turbines and other heat motors as
reciprocating engines can be started quickest. The speed of power change is clearly the highest for
heat motors and their minimum power is low. Also steam and combined heat and power plants
can be utilised in the relatively quick increasing of the electricity generation. Slower power changes
are possible also with the nuclear power but they cannot be carried out continuously. The
regulation characteristics of hydro power are superb in comparison to the other electricity
generation methods. Besides the sun power, wind power is increasing most quickly in the world in
the coming years. The modern wind power plants are able to active and reactive power control.
Storage systems can contribute to the frequency and voltage control mechanisms. Charging and
discharging of the storage system at the right moments (response within milli-seconds to seconds)
can help to preserve the balance between consumption and generation. Storages can also provide
secondary and tertiary frequency control. Static compensation devices maintain desired voltage
level by feeding the grid with necessary reactive power. FACTS devices and cross-border
connections based on HVDC converter schemes can play an important role in frequency and
voltage support. Demand response, including industrial loads and household devices and electric
vehicles, will have great influence in flexible operation of the grid.
This report describes appropriate models that characterize the interactions across control
boundaries under normal and emergency situations, introducing suitable data rates and models of
use by real-time control functions. In the future power system scheme, TSOs will be able to control
significantly smaller part of the generation compared to the traditional centralized configuration,
and thus they will not be able any more to compensate large deviations in the power balance.
Moreover, increased electricity loads and sources such as EVs and residential PV systems, will
influence the balance between day-ahead production and consumption schedule and will leave
energy markets with higher and less predictable need for balancing power. The actors involved in
the future grid control are balance responsible Party (BRP), cell system operator (CSO), cell
operational information system (COIS), distribution system operator (DSO). Their respective roles
are described and these actors play roles both to technical and market operations. Considering the
web of cells concept developed in this project, the generation units will be smaller and in many
cases these will be renewable resources which are less suitable for frequency control [1]. For that
reason a more important role for participation at the demand side will be expected for voltage and
frequency control in the future. The report describes “model based interfaces”, where the flexibility
user and the flexibility contributor agree on a simplified model which describes the actual behaviour
and constraints of the flexibility resource. Main outcomes of the work are the definition of controller conflict from a flexible power system perspective, a review of state of the art in power system control conflict and an outline of the methodology for identifying these conflicts during system operation and their impact on system stability. The report summaries the main findings from the literature and from project participant’s experience in terms of scenarios or examples of controller interactions resulting in conflict. A measure of controller conflict is presented for each example. This can be used as an indicator of the impact of controller conflict on system stability. Suggestions for resolving controller conflict are
also presented. The report describes the methodology proposed to construct such a dynamic
model for the purposes of extracting conflicting interactions of interest from the point of view
frequency and voltage stability. From the voltage stability perspective there are many factors which
may significantly influence the environment for voltage stability. It seems quite certain, that
possible conflicts affecting voltage stability may occur mainly due to lack of proper coordination
among players in the system voltage control and reactive power reserves management which are
TSOs, DSOs, Generators and Aggregators. Generally the scenery foreseen for frequency, voltage
and reactive power control in 2030+ is much more complicated than it is presently.
An overview of experiences from the ELECTRA partners regarding the realization of controllers in
demonstration and field test projects are also provided. It summarizes best practices and lessons
learned which will provide valuable inputs for the implementation of control concepts and their
testing and validation. The main requirements for controllers are reliability, fault tolerance and
robustness.
| Original language | English |
|---|
| Number of pages | 118 |
|---|---|
| Publication status | Published - 2015 |
