The main purpose of the system defining its formation principles is to provide opportunities for managers of different level to make decisions based on the objective facts but not the experts’ assessments or assumptions. To achieve this purpose it is necessary to take into consideration the following general principles of system formation: * fewer information systems and interfaces; * integrated information architecture; * optimisation operative preparation and revision; * simple, convenient and fast input of the scheme; * simple, convenient and fast correction of parameters; * reviewing of the entire depreciation period; * reviewing of multiple alternatives; * automation and integration of the process; * selection of the essential information to be submit to managers of different level. The optimisation system must be users’ friendly. For the purpose of investment efficiency analysis the opportunity is to be provided for managers of different level to make decisions based on objective calculations but not on the experts’ opinions or assumptions. When solving development tasks the opportunity is also to be provided to operatively prepare the object, and, with the information specified, to quickly rerun optimisation and to correct further decisions. In 2001, the EMML elaborated two new program packets of technically- economic analysis and optimisation - LDM-VZ’01 and LDM-AVE’01. The LDM-VZ’01 program packet is meant for dynamic optimisation of low and medium voltage networks and investment efficiency analysis, performing such analysis for upgraded and newly built low voltage networks and transformer units (20/0,4 or 10/0,4 kV) under uncertain informational conditions, applying the criterion of current values. The mentioned program packet is intended for application on the level of distribution networks. The other program packet - LDM-AVE’01 - is devoted to dynamic optimisation of high and medium voltage networks and investment efficiency analysis and is capable of performing such analysis for 330-110-20-10-6 kV networks that are under upgrading or newly built, including investment efficiency analysis of local electric power plants, applying methods of technically-economic calculations and dynamic optimisation of the network development. Both program packets are based on the above-mentioned principles and are structured identically. The software is programmed in the Delphi language applying all the advantages of the Windows operating system. They are composed of 4 blocks: a data block, a dynamic optimisation block, a block for analysing technically-economic options, and a block of decision making under uncertain informational conditions. Both the software systems provide the following opportunities: 1. to eliminate investments that would elevate production costs; 2. to arrange the investments demanded according to their efficiency. These are envisaged for Pentium III personal computers and Windows’ 98 operating system. The LDM database is created by attaching, step-by-step, network objects. As compared with the previous LDM program packets, operating the new software is essentially simplified, which significantly reduces errors.