You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Energy big data: A survey 
Chapter Title:  B. DATA QUALITY 
1. Abstract of Cited Paper (BIB001):  We study the problem of clustering data objects whose locations are uncertain. A data object is represented by an uncertainty region over which a probability density function (pdf) is defined. One method to cluster uncertain objects of this sort is to apply the UK-means algorithm, which is based on the traditional K-means algorithm. In UK-means, an object is assigned to the cluster whose representative has the smallest expected distance to the object. For arbitrary pdf, calculating the expected distance between an object and a cluster representative requires expensive integration computation. We study various pruning methods to avoid such expensive expected distance calculation.

Literature Review:
Due to the multiple origins of big data in the complicated power system, the smart grid database always contains incomplete, inconsistent and uncorrected data. Therefore, a series of data preprocessing technologies are necessary to improve the data quality, especially after uncertain data mining and imprecise querying BIB002 . Data preprocessing contains data manipulation, compression and normalization of the older data into improved format BIB001 . Data manipulation refers to transformation, which is used to reduce the impact from data fault sensing and provide more reliable energy data. The compression operation is used for massive data measurements to be reduced into a reasonable extent. Meanwhile, the normalization technology is used to regulate the collected data by minimizing its noise, inconsistencies and incompleteness of data. These three operations are main components of data preprocessing but the order is not unique. Furthermore, different regulations on big data cause conflicts between collaborators and lead to inconvenience in smart grid. Therefore, a unified and complete system standard needs to be set up in the future.