A puzzle to be solved: Economic dispatch of combine cycle co-gen plants

BY EHTESHAM UDDIN

In Asian Power market, “Middle East” is the largest economy having higher concentration of dual purpose power and water plants, mainly due to the requirement of desalinated water in this part of the world and secondly it is the economical way to produce drinking water.

Economics Dispatching (ED) is one of the prime liabilities of system operators besides system security and safety. With increase in culture of de regulation within GCC states, system operators are under immense pressure to milk every BTU of fuel and convert it into economic production of Power and Water all together.

For economic operations, combine cycle co-generation plants are common in gulf countries, however with the constraints of system networks and increasing trend of interconnections made the puzzle of economic dispatch even more complicated.

Optimization is the main objective function of any Economic Dispatch (ED) program, such that its output not only satisfied the forecasted power and water demand but provides sufficient statuary requirements of operating reserves and simultaneously addresses the issue of cross border exchanges.

“Icing on the cake” is the network constraints, though power transmission network has its own bottle necks and congestion problem and ED program has to take care all these as well, however the real challenge is simultaneous solving the equation for water zonal demand and deal with water network constraints.

Unlike power transmission network, water transmission system generally is not bi directional depending on the pumping and storage facilities in different demand zones.

All these parameters have to be solved in chorus for optimization within ED program; hence these factors in the multi dimensional array of ED program’s “objective function” required more SMART solution. State of the art techniques, well-built modeling and strong algorithms are the main ingredients of a SMART approach to economic dispatch scheduling and unit commitment.

Usually “Unit Commitment” and economic scheduling are done over a horizon of 24 hours in advance, hence provide a short term planned scenario for real time operators to execute. Real challenge arises when any major disturbance in network or cross border exchange upset the whole execution of economic dispatch process and system operators just rely on their engineering sense or some manual crude ways of decision making.

It is required to operate ED as cyclic process, continually update itself with the varying conditions of real time network or set certain triggers to invoke its calculation cycle.

Emirates of Abu Dhabi is having a regulator observing the performance of whole power and water sector and economic dispatching is one of the license condition that has to be satisfied by system operators, therefore a customized software is in place to achieve this target.

However more advanced solutions are required to achieve higher degree of performance both operationally and economically. Technology and solution providers may come up with innovative ideas laced with modern expertise and pushed ED process into the era of SMART GRID.

The views expressed in this column are the author's own and do not necessarily reflect this publication's view, and this article is not edited by Asian Power. The author was not remunerated for this article.