Study Of Impact Of Frequency Deviation On Power System

INTRODUCTION
1.1 BACKGROUND OF THE STUDY
The operation and the development of power system networks introduce new types of stability problems [Abdulraheem et al, 2016]. The effect of the power generation and consumption on the frequency of the power system can be described as a demand/generation imbalance resulting from a loss of generation or load manifests itself as a variation in the system frequency [Qazi et al, 2016]. A high demand on consumption will cause system frequency to decrease, while low demand on consumption will increase the system frequency, and vice versa with the generation [Kirby et al, 2013]. There are many possible parameters involved when analysing the problems associated with the controlled operation of the power systems [Kirby et al, 2013].
A power system is a highly nonlinear system and its dynamic response is influenced by a wide range of devices with different characteristics and response rates [Kirby et al, 2013]. Characteristics such as rapid load changes and generation outputs, loss of synchronisation among generators, short-circuiting on the transmission, and other operating parameters that are affected by the changes of the environment and operational disturbances.
Although the power systems are designed to withstand wide-ranging disturbances, stability of the power system becomes remarkably unstable with the greater. The potential of research in investigating how power generation–consumption and frequency stability affect the overall performance of the power grid system, including the parameters that define and determine the frequency output after a disturbance, has remarkably increased [Saleh et al, 2013].
At the generation side, the rotational speed of synchronous machines is directly proportional to the systems frequency [Kundur et al, 2014]. Frequency stability refers to the ability of the power system to maintain steady frequency following a severe system disturbance resulting in a significant imbalance between generation and load [Kundur et al, 2014]. Deviations in frequency will result in the use of control applications to regulate the frequency of the power grid to the safe and satisfactory levels [Sarma et al, 2014]. The UK Grid regulates frequency to be maintained at 1% of the nominal system frequency (50 Hz), except at exceptional circumstances [Kundur et al, 2014].
Demand Side Response (DSR) is a real-time intervention using energy controlled applications when the power systems is disturbed or stressed [Kundur et al, 2014]. Load-shedding is a coordinated controlled response which results in reduction in electrical load, this relieves stress on the main power system [Kundur et al, 2014].
The frequency measurements are compared to European electrical standards EN 50160 [Meegahapola, 2010] and EN 50160/A1 [Qazi, 2016] in order to establish if the frequency deviations in the grid during islanded operation surpasses the range set for systems without synchronous connection to an interconnected system. The frequency variations are also compared to International Electrotechnical Commission (IEC) Standard 60034-1 [Teng et al, 2015], computer power supply ATX12V design specifications [Wood, et al, 2013], Intel power supply design specifications [Kerahroudi et al, 2015] and IEC Standard 60076-1 [Kundur et al, 2014] to predict possible effects on connected equipment.

1.2 PROBLEM STATEMENT
Power systems are complex systems consisting of large number of generating units and interconnected network of transmission lines. The frequency deviation is an issue of prime importance in this complex power system network since the demand for electric power is increasing drastically. The tendency of a power system to develop restoring forces equal to or greater than the disturbing forces to maintain the state of equilibrium is known as stability. Frequency deviation is one of the power stability problems commonly noticed in power system. A high demand on consumption will cause system frequency to decrease, while low demand on consumption will increase the system frequency, and vice versa with the generation. This study was carried out to study the impact of frequency deviation on power system.

1.3 OBJECTIVE OF THE STUDY
The objective of this work is to carry out a study on the impact of frequency deviation of power system.

1.4 SIGNIFICANCE OF THE STUDY
This study will be of great benefit to the reader in that it will help the reader to understand the effect of frequency deviation in power system also the make known to the reader the causes of frequency deviation in power system.

1.5 SCOPE OF THE STUDY
The scope of this work is on the investigation of the effect of frequency deviation on power system. This paper investigates the impact of frequency deviation on power system. A simplified power system model is proposed to examine the impact of change of the main generation system parameters (system inertia, governor droop setting, load damping constant, and the high-pressure steam turbine power fraction), on the primary frequency response in responding to the disturbance on the power grid.