An analysis of technical aspects of smart grid technologies integration into power system of megacity

摘要

In this paper an analysis of terms of Smart grid technology integration with highpower system of megacity is given by the example of the Moscow region which maximumwinter load is about 18 GW. An experience of system restoration after large blackout in May2005 is considered, as well as the peculiarities of development and operation of such kind ofsystem that have strong interconnections with the bulk power system at the voltage of 500 kV.The significant peculiarities of the power system are:1. high concentration of power engineering facilities in a limited area and highratings of single installations,2. combined operation of different type sources of high and small power,3. electrical closeness of the power stations and high short currents,4. high dynamic of load growth and density, high variation of load profile withday and seasonal fluctuations,5. heat-and-power generation with mutual influence of heat and powerconsumption,6. difficulties in planning and operation of heterogeneous networks of high andlow voltage,7. significant growth of dispersed generation of small power,8. many important consumers, including a life-support infrastructure of themegacity (water supply, heating, tube railway and oth.),9. high risks of dramatic consequences of system blackouts,10. difficulty in application of centralized emergency control system.The power system of megacity must meet high reliability and survivabilityrequirements. Therefore it must have a number of specific features: balance load andgeneration of different types, have a back-up from the bulk-power system, comply with fueldiversity, have generation and transmission capacity reserves in case of loss of large powerengineering facility. In the event of emergencies the power system must maintainsurvivability, preventing cascading and voltage collapse, sustaining power supply ofimportant consumers and providing rapid power supply restoration.These problems need complex solution under the development of megacity, includingthe provision of small sources’ technological interoperability, networks conjunction ofdifferent voltage classes from 500 kV for the external interconnections to 10(20) kV for thedistribution, a disposition and capacity of backbone substations, ring ties configuration, aharmonization with territory zoning and development of roads, collecting canals and oth.A range of problems can be solved by the new technologies of Smart grid. Firstly inimprovement of observability, controllability, restoration, survivability and oth. Importantplaces of these technologies application are the interfaces on the borders of power supplysystem at 110-220 kV of the megacity with a bulk-power system at 220-500(750) kV, lowvoltagenetwork 6-10(20) kV with high-voltage part of the power system of megacity. Alsoon the border of consumers connection, including crucially important consumers and thosedirectly connected to high-voltage substations or generation voltage busses, and in places of110-220 kV network sectioning.The paper presents findings of the new requirements for the reliability of megacitypower supply system application and the assessment of their adoption is given. A singlestandard (reference) contingency includes the loss of large power plant, substation or cablecollecting canals in the megacity. Furthermore the limitations on concentration of powerengineering facilities, requirement for mutual reserving of power plants and backbonesubstations in the megacity, and requirements for external and internal power supply of themegacity and its consumers are given.The assessment of flexible and controllable ties application in the places of 110-220 kV networks sectioning as well as their influence on the quality and reliability of supplyimprovement, short current limitation and avoidance of transit flows is given.A large number of important consumers in the megacity that tolerate no interruptionleads to adverse consequences of the system blackout and rises social risks. This requiresmaking not only reliable external power supply schemes but solving the problem ofconsumers self-reserving and individual life-support system installation too. In the event ofinterruptions in the power supply network of general use this system must provide safeoperation or safe and troubleproof termination of technology process.Stringent requirements for the reliability of power supply calls for fast and selectivedemand control. Intelligent protection system and technology of microgrid control are neededto prevent system collapse and provide restoration.