Generation Management System

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In considering the energy crisis and sustainable development, renewable energy generation is becoming more and more important, beside conventional bulk generation. Compared to conventional generation (thermal power, hydroelectric power, nuclear generation, etc.), renewable energy generation (wind power, solar power, etc.) is much more uncertain. It is a great challenge to interconnect renewable energy generation to power systems. Therefore, one important task of Smart Grid is to provide a dynamic platform for free and safe interconnection of renewable energy generation to power systems, including the impact of these large renewable energy generation plants on the monitoring and control of the conventional one. Smart Grid will play an important role in ensuring power supply security and sustainable development.

According to different kinds of energy, generation can be classified into the following categories:
·     wind power (testing and certification of wind turbines, design requirements of wind turbines, assessment and measurement of wind power, etc.);
·     solar power (test and certification of photovoltaic devices, utility interface of photovoltaic systems, over-voltage protection of photovoltaic systems, assessment and measurement of solar power);
·     marine power (design requirements for marine energy systems, assessment of performance of wave energy converters, etc.);
·     fuel cell (safety of fuel cell power systems, performance test method for fuel, etc.);
·     Battery Energy Storage Systems, or BESS (battery safety, battery management, etc.);
·     Hydroelectric power, including pumped storage (acceptance tests of hydraulic turbines, storage pumps and pump-turbines, etc.);
·     distributed generation (distributed resources interconnected with power systems, design, test interconnecting and protection of small renewable energy and hybrid systems for rural electrification, etc.);
·     nuclear generation (interconnecting of nuclear generation, etc.);
·     conventional generation (test and certification for hydraulic turbines, communication networks for power utility automation, interconnecting of conventional power plants to power systems, active power and frequency control, ancillary services, reliability standards, protection and control, etc.)

Nowadays large-scale solar photovoltaic generation plants the size of 10 GW are under construction, and also large-scale wind power fields. These plants in such a large size will bring great challenges to power system security. Interconnecting standards for large-scale renewable energy generation plants are urgently needed.

Marine power generation will typically have different load profiles that are highly variable as far as resources are concerned. For tidal power, these load profiles are predictable; however, for wave power, the nature of the resource results in an intermittent loading profiling, similar to some extent to wind energy. Where a Smart Grid is to be designed to incorporate a wave or tidal generation unit, the designer shall take into account the intermittency and possible profiles of this generation. The designer shall consider the requirements and information provided in the IEC 62600 series. Designers of Smart Grids that are to incorporate a wave or tidal generation unit shall consider the work programme of TC 114 in order to identify any forthcoming documents that could be relevant

A growing share of renewable energy sources connected to the power grid is foreseen and will lead to a steady transition towards a complex combination of a few large centralized power plants and a great number of small and decentralized power generating facilities. Integrating these facilities into a reliable and affordable power system will require an unprecedented level of co-operative action within the electric industry and between the industry and states.

Flexibility is a more and more important issue for power system. The Generation management system will address such challenges as:
·     expand sub-hourly dispatch and intra-hour scheduling;
·     improve reserves management;
·     improve ancillary services management;
·     access greater flexibility in the dispatch of existing generating plants;
·     focus on flexibility for new generating plants;
·     focus on Virtual Power Plant (VPP) and hybrid power plant.

The standards listed below are available on  IEC webstore.

As shown in the Figure above, the Generation operation component architecture involves all Zones from Process to Enterprise levels, which may be interconnected through wires or communication.

The lower level components are easily identified as Generation related or not. The higher level components are more tightly integrated with Market, Asset Management and Transmission related components.

The Process level is populated with:
·     electrical equipment, sensors and actuators (such as current and voltage transformers, breakers or switches);
·     electro-mechanical machines with associated sensors and actuators (turbines and generators);
·     industrial equipment with general purpose sensors and actuators (typically hydro or thermal plant).

The Field level is in charge of protection, monitoring and control. It is mostly based on PLCs, which can be replaced by IEDs for electrical equipment.

Above the DCS HMI, higher level components are to be integrated with Market, Asset Management and Transmission related components.

The Transmission EMS/SCADA system communicates with the Generation Management System RTU to implement the Secondary Generation Control.

Within the Generation management system, the significant communication protocols, as shown in the Figure above, are the following:
·     Field bus protocols are standardized within IEC 61158 series and IEC 61784-1.
·     Mission-critical networks hosted in Station level rely on IEC 62439 series high availability automation networks.
·     The communication standards of the IEC 60870-5 family (profiles 101 and 104 to connect to the Plant, profile 103 to connect to protection Relays).
·     The messaging standard IEC 61968-100 for Enterprise and Operation level messages.
·     The communication standards of the IEC 61850 family for IED components.
·     The communication standards of the IEC 62541 family for OPC UA servers and clients.

This set of standards can be positioned in this way on the communication layer of SGAM.

The information layer of Generation management, presented in the Figure above, is based on the following families of information models:
·     Field device functions and interfaces are standardized within IEC 61131 series, with associated work in progress: IEC 61499 and IEC 61804 series.
·     Plant electrical devices are standardized within the IEC 61850 series, with work in progress for other field devices: IEC 61400-25-2 for wind turbines, IEC 61850-7-410 for hydro power plants.
·     Industrial plant information models are standardized in the following family: IEC 62264 series (ISA 95), IEC 61512 (ISA 88), IEC 61987 series and IEC 61360. Their relevance to the Generation management system is at the Station level.

Operation and Enterprise level information models are standardized in the CIM family: IEC 61968, IEC 61970, IEC 62325 series and IEC 62361. The relevance of IEC 61968 parts to Generation has not been formally assessed yet. Few parts are fully appropriate for Generation domain, but most parts can be extended to become relevant to Generation domain.

Mappings between most of these information models and the IEC 62541 address space are defined or in progress.