E3S Web of Conferences 25, 03009 (2017) DOI: 10.1051/e3sconf/20172503009 RSES 2017 Disintegration of power grid as part of the task of increasing functionality of electric system Bekzhan Mukatov1*, Alexander Fishov2 1JSC “KEGOC”, National Dispatch Center of the System Operator, Z00T2D0, Astana, Kazakhstan 2Novosibirsk State Technical University, 630073, Novosibirsk, Russia Abstract. When operating electric power systems there are often situations in which the power systems operation is inevitable with reduced reliability or, otherwise, with incomplete functionality where functionality is the set of functions provided by the power system and the quality of their performance. With the mass input of distributed small generation in grids of almost all voltage classes it is necessary to solve the problem of ensuring stability in previously passive distribution networks. The traditional approach based on the “struggle” to maintain synchronism between power plants in the distribution networks is associated with a number of difficulties, which causes to apply another approach to control modes in distribution networks. Complication of the power grid, automatic devices, increase in possible variations of modes, and tendency to maximize the use of production assets lead to an increase in the complexity of tasks solved by dispatch centers. In this regard, it is important to note that availability of cascade failures in power systems speaks of the urgency of the task of ensuring the survivability of energy supply systems both globally and locally. The paper shows how disintegration of the power grid can solve the task of ensuring the functionality of traditional power systems and help to create favorable conditions for distributed small generation integration into the integrated electric power system. allocation of balanced subsystems to isolated work depending on the current mode. Unlike traditional EPS 1 The study of potential of power grid where the integral structure is a carrier of reliability, in disintegration adaptive EPS due to the development of the power system survivability feature preventive disintegration In traditional power grids functionality is provided by becomes the basis of reliability [1,2]. the integrity of structure and system mode, i.e. stability Disintegration of power grid with reduced of parallel operation of all power plants. To do this functionality is capable of raising its level or restoring restrictions are imposed on the power transmitted over it completely due to the effective use of EPS internal the network in the form of capacity reserves, and a reserves of structural nature. These reserves include: complicated emergency control system is maintained. the use of the regulating effect of load in In such electric power systems (EPS) disintegration frequency and voltage; (division of the power grid into parts) refers to increase in permissible power flows exceptional measures of impact on the mode in order to corresponding to the regulatory stability reserves ensure survivability of EPS. which can be achieved by reducing irregular Currently, development and operation of power fluctuations, by reducing (up to complete systems are based on the invariance of the network elimination) the total consumption in one of the switching scheme to their modes. At the same time, the intersectional subsystem; network disintegration potential is underused to ensure reliability of the power supply system and ensure its forced power flow to relieve overload on the survivability. Disintegration of network is used to electric power line due to the load of other separate the district or power plant for isolated work unloaded elements. with an approximately balanced load in a Disintegration of EPS can be used to re-commute predetermined section, as well as to terminate the the circuit in such a way that the system survivability asynchronous mode in section that connects non- increases under severe system conditions (for example, synchronous parts. deep frequency reduction in the region), as well as in In networks with an adaptive structure the modes where n-1 criterion is not met. This is especially reliability and quality of power supply is more important in the power system operating conditions determined by the system's ability to balance the with reduced stability reserves. separation and post reduction of the system integrity. Currently, with a decrease in functionality due to Functionality may to a considerable extent be provided non-compliance with the requirements for stability by changing the configuration of power grid with reserves, i.e. in increased risk modes (IRM), the * Corresponding author: [email protected] © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). E3S Web of Conferences 25, 03009 (2017) DOI: 10.1051/e3sconf/20172503009 RSES 2017 Power System 21 Dossor 17+j13 25 38+j20 14+j6 Zhezkazgan 166+j107 possibility of implementing such mode, as a rule, is Calculations were carried out using “RastrWin” and 24 Atyrau Mirgalimsay 52+j36 Kashagan 15 MW 94+j11 CHPP Mahambet 10-j5 38+j17 1200+j840 provided by Emergency Control Automatics (ECA) “Mustang” software complexes for modes calculation. Agadyr S=95 Inder Zhambyl with an impact on load shedding or generation. Thus, Kumyskul MVA 13-j14 TPP Atyrau 15 MW 45-j5 Kulsary Kulsary 40+j30 52+j3 Table 1. The volume of control actions in case of designed 6-j2 12 20 39+j13 22 31 1 in case of system integrity and line shutdown in section Otp disturbances 16+j5 1 or generator in subsystem 2 (Fig. 1a), the Stability 33 Karaton 59-j20 32 26 2 Tengiz 47-j156 13+j145Frunze 66+j12 Pravoberezhnaya Control Schemes (SCS) will unload the section 1 due Power transmission Shutdown of 200 MW Tengiz Shymkent Shu YUKGRES Designed disturbances Zhambyl GTPP 100+j47 Almaty Alma line shutdown in generation in 3 548+j2 to the load shedding in subsystem 2. 19 17 98-j107 section 1 subsystem 2 Beineu 594+j60 165+j108 Reconfiguration Reconfiguration Toktogul 92+j5 246-j20 According According Syrdaria HPP 103-j9 Method of reliability Tashkent TPP According According to the to the TPP assurance SCS SCS to the to the scheme of scheme of Power System scheme of scheme of Fig.1 b) Fig.1 c) Fig.4. Result of MAS operation on searching for fission cross Fig.1 b) Fig.1 c) sections per hour of maximum. Shutdown of Fig.2. Initial conditions of EPS of the Western part of EPS of generators 0 0 200 0 0 0 the Republic of Kazakhstan. To compare the results of MAS operation with Fig. 1. IRM (а) and EPS disintegration modes that exclude Load shedding 400 250 0 200 50 0 traditional automatics, the fission cross sections IRM (b, c), where P – section loading in IRM, P max – the Compensation In the original scheme, the overhead line between (double continuous line) performed by the centralized of unbalance maximum permissible flow in section. due to 0 0 200 0 0 200 nodes 22 and 24 is overloaded (Atyrau TPP – Kulsary division automatics are shown in the same figures. regulating SS). In the scheme of a certain MAS division, the IRM can be excluded or passed with more and Control compensating MW actions, effect of load The MAS performed reconfiguration, as a result of amount of disconnected load in the southern part of the functionality due to the power grid disintegration. In which bars were electrically separated at the Kulsary Kazakhstan’s power grid is about 350 and 200 MW at Fig. 1 shows the options of power grid disintegration to 2 Decentralized reconfiguration of active substation and part of the overhead line was switched the time of maximum and minimum, respectively. The demonstrate the effectiveness of its application to to 1 busbar, the other part to 2 busbar. Taking into volume of restrictions during operation of the improve functionality in IRM. electrical distribution network account the possible combinations in distribution of traditional division automatics in similar hours is more According to [3] permissible overflow on static Active increase in the number of distributed small loads on the bars, the minimum possible load was than 2 times higher. transferred to the 2 busbar with preservation of stability with normative reserves on active power ( kp ) generation (DSG) facilities with their inclusion in parallel operation of the power grid poses the problem communication with transformer of Kulsary substation. in section is calculated according to the formula (1): 3 Preventive disintegration in active of development of technologies for modes management The result of reconfiguration is shown in Fig.3. electrical networks to ensure their effective integration into EPS [4-8]. 17+j13 P Plim 1 k p Pif (1) 21Dossor Input of DSG in the previously passive power 24 An analysis of transient modes when connecting small distribution networks (DN) radically alters their Atyrau 52+j36 81+j12 CHPP Mahambet generation to electric network and short circuit in the where Plim – active-power flow that is limit original properties, turning the passive DN into active S=82 power system [2] showed that due to strong according to non-periodic static stability in the reviews power grids - the power systems [9-13]. Kumyskul MVA 44 74-j7 12 Atyrau connections between subsystems there is a high section; P – the flow in section in the reviewed mode, In view of the existing difficulties in Kulsary Kulsary 20 9+j3 22 23+j10 probability of occurrence of unacceptable shock implementation of centralized management of modes Otp Pif – the amplitude of irregular fluctuations of active 0,4-j0,5 31 moments on synchronous machine shafts, disturbances of the active distribution network, the existing 33 Karaton 32 26 power in this section. of dynamic stability that are capable of causing their traditional management technology is too costly for damage.