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The capability curve for each generator unit is usually provided by the generator manufacturer. But in practice, the generator can reach its maximum generation limit before reaching the maximum limit on the generator capability curve provided by the generator manufacturer. This might occur because of the load location is far from the generator or the varying of the loading value so that the maximum generation limit is smaller than the value given on the generator capability curve of the manufacturer. In this paper, the generator capability curve is determined using the Modified Single Machine to Infinite Bus (M-SMIB) system approach to determine the maximum generation limit every time there is a change in loading or change in the load location. After the maximum generation limit of each unit generator is known, the generator capability curve that is always in accordance with the real time situation can be formed. Thus, the operation limit of each generator can be recognized, determine the appropriate protection system setting and can prevent the electric power system disturbance. This method will be applied to generator units in the four bus IEEE system with two generators.

The indicator of the power system operation stability can be seen from the power balance between the load demand and the generator output power. The Single Machine to Infinite Bus (SMIB) system that can actually represent the operation of a single machine system in a multimachine system can be used to analyze each generator unit stability. This paper present a fairly simple method to determine the generator steady state stability limit on the Jawa Bali 500 kV system using an SMIB system approach consider the load configuration changes in the system. The Radial Basis Function Neural Network (RBFNN) is applied to simplify the determination of the generator steady state stability limit that changes every time a load configuration changes. The simulation results carried out on the Java Bali system 500 kV 29 bus 10 generators can be seen that the steady state stability limit of each generator unit tends to decrease with the increasing of loading value and the further of load distance from the generator. Keseimbangan daya antara kebutuhan beban dengan pembangkitan generator merupakan salah satu ukuran kestabilan operasi sistem tenaga listrik., Untuk menganalisis kestabilan setiap unit generator dalam sistem multimachine harus dilakukan pada sistem Single Machine to Infinite Bus (SMIB) yang secara aktual dapat mewakili keadaan sistem single machine tersebut dalam sebuah sistem multimachine. Dalam paper ini digunakan suatu metode sederhana untuk menentukan batas kestabilan steady state setiap unit generator pada sistem multimachine Jawa Bali 500 kV menggunakan pendekatan model sistem SMIB dengan memperhatikan perubahan konfigurasi peletakan beban dalam sistem. Untuk memudahkan penentuan batas kestabilan steady state generator yang selalu berubah setiap saat terjadi perubahan peletakan beban, diaplikasikan salah satu model jaring syaraf tiruan yaitu Radial Basis Function Neural Network (RBFNN). Dari hasil simulasi yang dilakukan pada sistem Jawa Bali 500 kV 29 bus 10 generator dapat diketahui bahwa batas kestabilan steady state setiap unit generator cenderung menurun dengan semakin meningkatnya nilai pembebanan dan semakin jauhnya jarak beban dari pembangkit.

Abstract. In the multimachine circumstances, it is difficult to analyze the steady state stability of each generator. In previous research, analysis of the steady state stability limit has been carried out but only look at the stability of the overall system. Therefore, to analyze the stability of each generator, the multimachine system must be changed into a Single Machine to Infinite Bus (SMIB) system by collecting all the loads into one central load in the infinite bus. The method to change from the multimachine system to SMIB system is presented in this paper. The multimachine system is converted into an equivalent impedance (req and xeq) and an equivalent load based on losses concept. After req and xeq is calculated, then by using steady state stability limit concept, the value of the maximum generation of each generator units can be determined. By means of maximum generation is the maximum output power limit that can be generated without causing unstability. ETAP simulation is used to validate the calculation results of the proposed method. The method was applied to units generator in Java Bali system 500 kV.

No abstract