Electricity System Operator EAD. Difficulties in Grid Planning & Development

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1 Electricity System Operator EAD Difficulties in Grid Planning & Development

2 The Electricity System Operator EAD is responsible for managing the Bulgarian power system, its parallel operation with other ENTSO-E member states systems, grid operation and maintenance activities, and electricity market operation 2

3 Difficulties in Ensuring the Security of Transmission Grid After decommissioning of Kozloduy NPP units 3 and 4 ( г.), generation output from Maritsa East and Varna TPP has increased considerably A substantial share of the internal generation capacity shifted from the highly developed Northwest to the weaker Southeast Bulgarian grid. Two new units x 345MW were commissioned 3 in Maritsa East area.

4 Difficulties in Ensuring the Security of Transmission Grid The System Operator (ESO) operates in a dynamic environment so as to guarantee the necessary level of HV grid security and keep supplies delivered in line with trading contracts. Current changes in the maintenance schedule are frequently necessary, which causes inconvenience and additional workload on ESO experts and those in charge of maintenance activities. 4

5 Difficulties in Ensuring the Security of Transmission Grid To deal with those issues, ESO and the grid owner, NEK, have planned to develop a number of new OHL s and significant grid reinforcement. The Bulgarian TYNDP is made publically available at During the current year ESO will draw up the new TYNDP

6 Issues with Providing the Necessary Future Genration Capacitues Difficulties expected with ensuring the needed future generation capacities in Bulgaria are related to decommissioning major conventional generation (without new replacements) and the connection of many wind and PV farms. 6

7 Issues with Providing the Necessary Future Genration Capacitues Until 2015, key conventional power plants should be taken out of operation, pursuant to a Programme for Implementation of Directive 2001/80/ЕC on the large combustion plants. The decommissioning of Varna TPP, Bobov Dol TPP and unit 4 of Rousse TPP will negatively impact both the overall active power balance in and the voltage control in adjacent regions. 7

8 Issues with Providing the Necessary Future Genration Capacitues Two main problems will arise: Technical issue in terms of significant decrease in security of supply, risk of overloading and interruption of supplies to end customers, inadmissible voltage deviations and deteriorated quality of supply Economical issue representing a risk of increase in electricity prices and impacting availability of reserve and ancillary services 8

9 Issues with Providing the Necessary Future Genration Capacitues To solve these problems, the following measures need to be taken: Install desulphurization plants in Varna and Bobov Dol TPP s; Build a new nuclear capacity with technology that enables generation control range of % on a 24-hour basis; Resume construction works on Yadenitsa reservoir, which will provide much more control leverage for Chaira PSPP; 9

10 Issues with Providing the Necessary Future Genration Capacitues Supervise RES connection to grid by regions; Small pondage HPP s to go under centralized dispatching by ESO, via DSO s; Provide funding for transmission grid development; Facilitate the deployment of new HPP s, PSPP s and bio plants; Stimulate night tariff electricity consumption 10

11 The Balance between Generation and Demand Major base generation capacities are NPP and TPP s supplemented by run-of-river HPP s, CHP and cogeneration. Main ancillary services (primary and secondary control, tertiary and cold reserve) are delivered by TPP s and reservoir HPP s. 11

12 The Balance between Generation and Demand Wind and PV throughput is directly dependant on wind and solar radiation intensity. Variations in wind and PV generation are compensated through the conventional power plants, mostly by hydro load adjustment. This causes system balancing issues in off-peak periods. 12

13 Renewables Integration in Bulgaria To secure real time system operation without compromising balance and scheduled exchanges with neighboring countries, our system s capacity to connect wind and PV plants is limited and conditioned on the existing control capacities and available control margins. Current estimations of ESO indicate that a total of 1800MW wind and 600MW PV power can be installed at most. In terms of power system operation, so far there are no limitations as to the integration of small HPP s and bio plants. 13

14 Renewables Integration in Bulgaria In System Operator s view, using wind energy should better be realized with large windfarms (above 50MW) whose control system is connected with ESO s SCADA. This would enable more efficient system balancing, including in night off-peak timeframe. Solar radiation use should be optimized by distributed generation from small PV plants and solar panels on roof structures in order to dampen output variations in weather conditions of moving broken clouds. 14

15 Renewables Integration in Bulgaria Due to design reasons, wind and PV plants deteriorate the quality of electricity at their grid connection points. Both wind and PV lead to frequent changes in TPP output, thus disturbing the normal operation mode of facilities and desulphurization units, with potential adverse environmental effects. Again for design reasons, RES cannot be involved in primary and secondary control. Nor can they participate in emergency countermeasures and post-fault system recovery. 15

16 Renewables Integration in Bulgaria Under the existing regulatory framework, and die to cumbersome terrain purchasing and designation procedures, it is not possible for the construction of power lines and substations to keep pace with RES development. It s difficult to develop the existing transmission infrastructure before having in place the necessary new OHL s because otherwise security of supply will decrease and the risk of cascade blackouts in large internal regions will increase. 16

17 Smart Grids In recent years, the principles and methodology for transmission grid development is changing under the influence of increasing consistence between ITC and electricity networks. Digital devices and controllers are increasingly being deployed in process and control systems, including everyday life. This new milestone in the evolution of electricity networks is generally known as smart grid. 17

18 Smart Grids The smart grid concept has been present in the Bulgarian transmission system for a long time (in contrast to West European transmission systems), initially express in terms of mechanical and analogue devices. This is because the Bulgarian grid like the Russian one was developed and evolved in conditions of limited funding and savings. Bulgarian transmission system s increased usability and robustness is achieved by large-scale deployment of devices ensuring optimal use of existing equipment and fault control capabilities. 18

19 Smart Grids Supervisory and control systems of systemrelevant power plants feature fault-ridethrough algorithms operating to keep generation units stable in disturbance events on the grid. System substations are equipped with automations that enable fast fault localization, self recovery of power supply in fault cases, and prevent disturbances from cascading, incl. over interconnected systems. 19

20 Smart Grids ESO has started the installation of a dynamic monitoring system (WAMS) to cover OHL s that have high risk of overloading. Thanks to thermal sensors installed on the conductors, the transmission capacity of Southeast Bulgarian grid during the winter months was increased by 16%. 20

21 Smart Grids Currently, the Bulgarian transmission system is in line with ENTSO-E standards and the smart grid concept is being developed by the Research & Development Plan Committee where ESO is also represented. 21

22 Smart Grids At distribution grid level (low and medium voltage), the smart grid implementation process is yet to begin. Distribution grids have the greatest potential to accommodate smart grids, ITC solutions, distributed generation and accumulating systems. 22

23 Thanks for your attention! 23